Miracle-dz/UniFAR-FTUs huggingface dataset:
Globally convergent algorithms for robust pole assignment by state feedback

It is observed that an algorithm proposed in 1985 by Kautsky, Nichols, and Van Dooren (KNV) amounts to maximizing, at each iteration, the determinant of the candidate closed-loop eigenvector matrix X with respect to one of its columns (with unit-length constraint), subject to the constraint that it remains an achievable closed-loop eigenvector matrix. This interpretation is used to prove convergence of the KNV algorithm. It is then shown that a more efficient algorithm is obtained if det (X) is concurrently maximized with respect to two columns of X, and such a scheme is easily extended to the case where the eigenvalues to be assigned include complex conjugate pairs. Variations exploiting the availability of multiple processors are suggested. Convergence properties of the proposed algorithms are established. Their superiority is demonstrated numerically.
High-frequency oscillations in a solar active region coronal loop

The Solar Eclipse Corona Imaging System (SECIS) was used to record high-cadence observations of the solar corona during the total solar eclipse of 1999 August 11. During the 2 min 23.5 s of totality, 6364 images were recorded simultaneously in each of the two channels: a white light channel, and the Fe XIV (5303 A ˚ ) ‘green line’ channel (cid:133) T , 2 MK (cid:134) . Here we report initial results from the SECIS experiment, including the discovery of a 6-s intensity oscillation in an active region coronal loop.
ON SPECTRAL ANALYSIS WITH MISSING OBSERVATIONS AND AMPLITUDE MODULATION

Abstract : The notion of an asymptotically stationary time series and its spectral analysis was consdered earlier (Bulletin of International Statistical Institte, 33rd Session, Paris). An important example of an asymptotically stationary time series is an amplitude modulated stationary time series. In ths note, the problem of spectral analysis of sttionary normal time series with missing observations, recently treated by Jones (Anna s Math. Stt. 32:455-461) is reated as a special case of the problem of spectral analysis of an amplitude modulated stationary normal time series. (Author)
A simple formulation of the delta-four-stream approximation for radiative transfer parameterizations

Abstract We present a systematic development of the delta-four-stream approximation for calculations of radiative fluxes in planetary atmospheres. We illustrate that an analytic solution for this approximation can be derived explicitly with minimum computational effort for flux calculations. Relative accuracy checks for reflection, transmission, and absorption for numerous asymmetry factors, single-scattering albedos, optical depths, and solar zenith angles have been performed with respect to the “exact” results computed from the adding method for radiative transfer. Overall, results from the delta-four-stream approximation yield relative accuracies within about 5%. This approximation is well suited to radiative transfer parameterizations involving flux and heating calculations in aerosol and cloudy atmospheres.
Impact of Urban Growth on Surface Climate: A Case Study in Oran, Algeria

The authors develop a land use map discriminating urban surfaces from other cover types over a semiarid region in North Africa and use it in a land surface model to assess the impact of urbanized land on surface energy, water, and carbon balances. Unlike in temperate climates where urbanization creates a marked heat island effect, this effect is not strongly marked in semiarid regions. During summer, the urban class results in an additional warming of 1.458C during daytime and 0.818C at night relative to that simulated for needleleaf trees under similar climate conditions. Seasonal temperatures show that urban areas are warmer than their surrounding areas during summer and slightly cooler in winter. The hydrological cycle is practically ‘‘shut down’’ during summer and is characterized by relatively large amounts of runoff in winter. The authors estimate the annual amount of carbon uptake to be 1.94 million metric tons with only 11.9% assimilated during the rainy season. However, if urbanization expands to reach 50% of the total area excluding forests, the annual total carbon uptake will decline by 35% and the July mean temperature would increase only 0.108C relative to the current situation. In contrast, if urbanization expands to 50% of the total land excluding forests and croplands but all short vegetation is replaced by native broadleaf deciduous trees, the annual carbon uptake would increase by 39% and the July mean temperature would decrease by 0.98C relative to the current configuration. These results provide guidelines for urban planners and land use managers and indicate possibilities for mitigating the urban heat.
The Modeling of Fuel Mass Fraction Variance Transport in Turbulent Stratified Flames: A Direct Numerical Simulation Study

Three-dimensional compressible simplified chemistry-based direct numerical simulations (DNS) of statistically planar turbulent stratified flames at global equivalence ratios ⟨φ⟩ = 0.7 and ⟨φ⟩ = 1.0 have been carried out to analyze the statistical behavior of the transport of the variance of the Favre fuel mass fraction fluctuations (where , and are Reynolds average, Favre mean, and Favre fluctuation of a general quantity q where ρ is the gas density) in the context of Reynolds-averaged Navier-Stokes (RANS) simulations. It has been found that algebraic expressions are inadequate for predicting in low Damköhler number combustion, and a transport equation for may need to be solved. The statistical behaviors of and the unclosed terms of the transport equation (i.e., the terms originating from turbulent transport T 1 , reaction rate T 3 , and molecular dissipation D 2) have been analyzed in detail. It has been found, that T 3 and D 2 remain leading order contributors to the transport in all cases, whereas, the contribution of T 1 remains small in ⟨φ⟩ = 1.0 cases, but plays a more important role in ⟨φ⟩ = 0.7 cases. Through an a-priori DNS analysis, the modeling of T 1, T 3, and D 2 has been addressed in detail. A model has been identified for T 1, which provides satisfactory agreement with the DNS data. The models for T 3 and D 2, which were originally proposed for high Damköhler number flames, have been modified for low Damköhler combustion in the context of RANS simulations, and the predictions of the modified models are found to be in good agreement with the corresponding quantities extracted from the DNS data.
Predictions and observations of SEU rates in space

This paper summarizes the available data on the observation and prediction of SEU rates in space. It considers three questions: 1. How good can a prediction be? 2. How bad can a prediction be? 3. How does the quality of the prediction depend on the type of orbit? The paper considers one hundred and twenty-six reports of predicted and observed rates. These include updated predictions for the CRRES devices. The analysis then excludes solar particle events, single event burnout, cases with poor statistics, and cases that are essentially duplicates; leaving 77 comparisons. The heavy ion predictions based on the CREME environments and the proton predictions based on the AP8 environments are both very successful for their basic environments, but are less accurate for low earth orbits (LEO). The quality of the results depends strongly on whether the predictions are based on tests with flight parts or with generic parts. The quality also depends on the use of the proper shielding around the part. The results appear consistent with suggested modifications in these environments based on recent space measurements. The methods that are used for upset rate predictions appear to be adequate for the current generation of devices.
Radii of immersed manifolds and nonexistence of immersions

Let M be a compact Riemannian manifold isometrically immersed in a complete Riemannian manifold N. By the radius of M in A7, we mean the minimum of radii of closed geodesic balls in A' which contain M. Using the concept of a radius, we will give a theorem about the nonexistence of isometric immersions, which is a generalization of J. D. Moore's result.
Novel Technique of Optimizing FOPID Controller Parameters Using BBBC for Higher Order System

ABSTRACT The authors present a computer-aided mode to optimize the fractional-order proportional integral derivative (FOPID) controller parameters including the integral order “λ” and derivative order “μ”. Big Bang–Big Crunch (BBBC) optimization technique is used here to serve the purpose. The proposed method is realized with a numerical example and unit step responses are obtained for various values of λ and μ. The simulated results justify the superiority of FOPID controller using BBBC, when compared with the recently published/available well-known method.
Testing the "strong" PAHs hypothesis. II. A quantitative link between DIBs and far-IR emission features

In Paper I (Malloci et al. 2003) we proved the profile invariance of the first permitted electronic transition of the typical Polycyclic Aromatic Hydrocarbon cation C32H14 + as a first necessary check for the "strong" PAHs hypothesis. In this paper we derive a quantitative relation between the intensities of the former band, which ought to be observable in absorption in the visible range, and those of the far-IR bands, which are predicted by the PAH model to be simultaneously present in emission. Contrary to the mid-IR bands, collectively known as "Unidentified Infrared Bands" (UIBs), which do not discriminate specific molecules, the far IR, skeletal bands can be expected to be a fingerprint of each single species. This fact provides a number of independent constraints which must be simultaneously fulfilled for a successful PAH identification. Our approach thus offers a powerful criterion for the identification of specific PAHs, both in the presently available ISO data and in those of the forthcoming SIRTF and Herschel missions. As an interesting by-product, we quantitatively evaluate the impact of isotopic substitutions ( 13 C→ 12 C and D →H) on the resulting infrared emission bands.
Robust Inference With Multiway Clustering

In this article we propose a variance estimator for the OLS estimator as well as for nonlinear estimators such as logit, probit, and GMM. This variance estimator enables cluster-robust inference when there is two-way or multiway clustering that is nonnested. The variance estimator extends the standard cluster-robust variance estimator or sandwich estimator for one-way clustering (e.g., Liang and Zeger 1986; Arellano 1987) and relies on similar relatively weak distributional assumptions. Our method is easily implemented in statistical packages, such as Stata and SAS, that already offer cluster-robust standard errors when there is one-way clustering. The method is demonstrated by a Monte Carlo analysis for a two-way random effects model; a Monte Carlo analysis of a placebo law that extends the state–year effects example of Bertrand, Duflo, and Mullainathan (2004) to two dimensions; and by application to studies in the empirical literature where two-way clustering is present.
Clouds and shortwave fluxes at Nauru. Part I: Retrieved cloud properties

Abstract The datasets currently being collected at the Atmospheric Radiation Measurement (ARM) program's sites on the islands of Nauru and Manus represent the longest time series of ground-based cloud measurements available in the tropical western Pacific region. In this and a companion paper, a shortwave flux closure study is presented using observations collected at the Nauru site between June 1999 and May 2000. This paper presents frequency of occurrence of nonprecipitating liquid and ice clouds detected by the millimeter wavelength cloud radar (MMCR) and statistics of retrieved microphysical properties. The companion paper presents results from a closure study in which the retrieved cloud properties are input to a radiative transfer model, and the modeled surface fluxes are compared to observations. The liquid cloud properties are retrieved from MMCR and microwave radiometer (MWR) measurements using a Bayesian retrieval technique. Properties of ice phase clouds are retrieved from MMCR measurements usi.
Topological field theory of the initial singularity of spacetime

We suggest a new solution of the initial spacetime singularity. In this approach the initial singularity of spacetime corresponds to a zero-size singular gravitational instanton characterized by a Riemannian metric configuration ( + + + + ) in dimension D = 4. Connected with some unexpected topological data corresponding to the zero scale of spacetime, the initial singularity is thus not considered in terms of divergences of physical fields but can be resolved within the framework of topological field theory. Then it is suggested that the `zero-scale singularity' can be understood in terms of topological invariants (in particular, the first Donaldson invariant ∑i(-1)ni). With this perspective, here we introduce a new topological index, connected with zero scale, of the form {Z}β = 0 = Tr (-1)s, which we call the `singularity invariant'. Interestingly, this invariant also corresponds to the invariant topological current yield by the hyperfinite II∞ von Neumann algebra describing the zero scale of spacetime. Then we suggest that the (pre-)spacetime is in thermodynamical equilibrium at the Planck-scale and is therefore subject to the KMS condition. This might correspond to a unification phase between the `physical state' (Planck scale) and the `topological state' (zero scale). Then we conjecture that the transition from the topological phase of the spacetime (around the zero scale) to the physical phase observed beyond the Planck scale should be deeply connected to the supersymmetry breaking of the N = 2 supergravity.
On the minimum audible angle

The difference limen for the azimuth of a source of pure tones was measured as a function of the frequency of the tone and the direction of the source. Tone pulses between 250 and 10 000 cps were sounded in the horizontal plane around the head of a subject seated in an anechoic chamber. The smallest angular separation that can be detected between the sources of two successive tone pulses (the minimum audible angle) was determined for each of three subjects. These threshold angles are analyzed in terms of the corresponding threshold changes in the phase, time, and intensity of the tone at the ears of the subject. A comparison of these thresholds with those reported for dichotic stimulation indicates that the resolution of the direction of a source is determined, at frequencies below about 1400 cps, by interaural differences in phase or time, and at higher frequencies by differences in intensity. When the conditions are optimal for temporal discrimination, the threshold for an interaural difference in time .
Stellar content of NGC 404 - The nearest S0 Galaxy

We report V−band and I−band CCD stellar and surface photometry of the galaxy NGC 404 , taken with HST WFPC2 and the 2.5 m Nordic telescope. The colour-magnitude diagram for the stars in this galaxy is typical of that of spheroidal systems (i.e. it lacks luminous, young stars but contains a large number of Asymptotic Giant Branch (AGB) and Red Giant Branch (RGB) stars). The disk of the galaxy is mostly dominated by red giant stars while its bulge consists of both the AGB and RGB population. Using the distance indicator technique, based on the tip of the red giant branch (TRGB), we find a distance of 3.42 ± 0.25 Mpc for this galaxy. Global photometric characteristic of this galaxy were then measured out to a radius of 3 � , giving V = 10. m 04 and I = 8. m 95. We find ( V − I) = 0.3 for the nucleus of NGC 404. The integral colour of the galaxy changes slightly along the radius, and its mean value is (V − I) = 1.1. On the HST images situated at 9 � from the galaxy center there are many red giants. This means that the size of the disk of NGC 404 exceeds 20 kpc. The value of the mean metallicity of the red giants in the disk is (Fe/H) = −1.11.
Heat Transfer Augmentation of a Co-Rotating Disk Assembly with Special Emphasis on the Lower Disk

Experiments were performed to map local heat transfer coefficients on an unobstructed co-rotating disk system simulating the internal component of a computer disk drive assembly. The disk diameter was twice as large as a hard drive, and the rotational speed up to 5000 rpm was studied. The effects of two parameters, on the heat transfer phenomena the Reynolds number from 6.587 × 10 4 to 3.096 × 10 5 and the non-dimensional disk-to-disk ratio (L/D) from 0.02 to 0.06, were observed. The disks were positioned horizontally, and heat transfer was measured for the top faces of both disks. Emphasis is given to the top face of the lower disk in this research, as less experimental data are available in the literature. A transient liquid crystal technique was employed for the measurements, and the results reveal an interesting pattern of the heat transfer rate in the gap for the upper surface of the lower disk. The overall heat transfer is much lower for the surface of the lower disk as compared to that of the top disk. The maximum average heat transfer rate was established to be at L/D = 0.04 for the case with the highest rotational speed.
The WR+OB Progenitor RY Scuti: Intensive Spectroscopy of Its Compact Double-Ring Nebula

We present a detailed spectroscopic analysis of the peculiar nebula around RY Scuti using data from the Space Telescope Imaging Spectrograph (STIS) and various ground-based observatories. This massive contact binary may represent a rapid evolutionary phase in transition to a short-period WR+OB system, and it is surrounded by a young nebula with unusual geometry. The ionized nebula is only about 1'' across, so STIS has allowed us to spatially resolve the spectrum of the star from its circumstellar nebula for the first time. Combining STIS data with ground-based spectra at optical and infrared wavelengths solves some geometric ambiguities posed by previous images and reveals the kinematic relationship between the nebular geometry and RY Scuti's complex emission-line profiles. We offer a new determination of the systemic velocity of 20 ± 3 km s-1, and we estimate the distance to RY Scuti as 1.8 ± 0.1 kpc. Nebular lines show subtle phase-dependent variability in addition to expected changes in equivalent width due to eclipses of stellar continuum. These changes in equivalent width yield an updated ephemeris, but a previously suggested period change is still uncertain after considering these new data. The nebula contains roughly 0.003 M☉ of material that is He- and N-rich and probably O-deficient compared to solar abundances, indicating that CNO-processed material has reached the surface in at least one component of the binary system. Diagnostic line ratios suggest that the electron density and temperature in the nebula are 2 × 105 cm-3 and ~9500 K, respectively. There are concentrated regions of higher density as well; emission knots seen around the rings suggest that common envelope mass loss during massive contact binary evolution may be characterized by strong azimuthal asymmetry and sporadic mass ejection events.
X-ray precursors to flares and filament eruptions

Aims. To study preflare X-ray brightenings as diagnostics of the destabilisation of flare-associated erupting filaments/prominences. Methods. We combine new observations from the Transition Region and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), as well as revisit events reported in the literature to date, in order to scrutinise the preflare activity during eight flare-associated filament eruptions. Results. The preflare activity occurs in the form of discrete, localised X-ray brightenings observed between 2 and 50 min before the impulsive phase of the flare and filament acceleration. These transient preflare brightenings are situated on or near (within 10 �� of) the polarity inversion line (PIL), coincident with emerging and/or canceling magnetic flux. The filaments begin to rise from the location of the preflare brightenings. In five out of eight events, the preflare brightenings were observed beneath the filament channel, close to the filament footpoint first observed to rise. Both thermal and nonthermal hard X-ray emissions during the preflare enhancement were detected with RHESSI, suggesting that both plasma heating and electron acceleration occurred at this time. The main energy release during the impulsive phase of the flare is observed close to (within 50 �� of) the preflare brightenings. The fast-rise phase of the filament eruption starts at the same time as the onset of the main flare or up to 5 min later. Conclusions. The preflare brightenings are precursors to the flare and filament eruption. These precursors represent distinct, localised instances of energy release, rather than a gradual energy release prior to the main flare. The X-ray precursors represent clearly observable signatures in the early stages of the eruption. Together with the timing of the filament fast-rise at or after the main flare onset, the X-ray precursors provide evidence for a tether-cutting mechanism initially manifested as localised magnetic reconnection being a common trigger for both flare emission and filament eruption.
Stress Distribution around an Elliptic Hole in an Infinite Micropolar Elastic Plate.

Abstract : The problem of stress distribution in an infinite micropolar plate, weakened by an elliptic hole, subject to a constant uniform tension at infinity perpendicular to the major axis of the elliptic hole is solved. The stress distribution is plotted along the direction of the major axis of the ellipse and stress concentration factors are determined for various material parameters and eccentricities. The results are compared with those of classical elasticity and couple stress theory. (Author)
Knowledge-Gradient Methods for Statistical Learning

We consider the class of fully sequential Bayesian information collection problems, a class that includes ranking and selection problems, multi-armed bandit problems, and many others. Although optimal policies for such problems are generally known to exist and to satisfy Bellman’s recursion, the curses of dimensionality prevent us from actually computing them except in a few very special cases. Motivated by this difficulty, we develop a general class of practical and theoretically well-founded information collection policies known as knowledge-gradient (KG) policies. KG policies have several attractive qualities: they are myopically optimal in general; they are asymptotically optimal in a broad class of problems; they are flexible and may be computed easily in a broad class of problems; and they perform well numerically in several well-studied ranking and selection problems compared with other state-of-the-art policies designed specifically for these problems.