Miracle-dz/UniFAR-FTUs huggingface dataset:
An EUV-selected sample of DA white dwarfs from the ROSAT All-Sky Survey — I. Optically derived stellar parameters

One of the most important results of the ROSAT All-Sky X-ray and EUY Surveys has been the detection of a large number of white dwarfs, allowing a detailed study of the general properties of DA white dwarf atmospheres to be carried out. However, this work relies on a knowledge of the effective temperatures, surface gravities and visual magnitudes. We present analyses of optical data from our follow-up programme, including the values of Teff, logg, mv and stellar mass obtained. We also list the PSPC and WFC count rates for each star. The distribution of masses and surface gravities derived from the optical work also provides important information about the sample of white dwarfs and gives some indication of possible selection biases. Comparing the ROSAT sample of 89 stars with the cooler optically selected sample of Bergeron, Saffer & Liebert reveals a statistically significant excess (~3 times the number found by them) of hot, massive DAs, which may represent a population of coalesced binary white dwarfs. As the optical and EUY samples do not cover the same range of white dwarf temperatures, the high­ mass excess may partly arise from differences in the cooling rates of 'normal' (~O.6-M0) and massive (> 1.0-M0) stars. Consequently, this feature is not necessarily the result of selection on the basis of EUY flux, and it might also be present in an optically selected sample covering an appropriate temperature range.
Improved Shewhart-type Runs-rules Nonparametric Sign Charts

Runs-rules are typically incorporated in control charts to increase their sensitivity to detect small process shifts. However, a drawback of this approach is that runs-rules charts are unable to detect large shifts quickly. In this article improved runs-rules are introduced to the nonparametric sign chart to address this limitation. Improved runs-rules are incorporated to maintain sensitivity to small process shifts, while having the added ability to detect large shifts in the process more efficiently. Performance comparisons between sign charts with runs-rules and sign charts with improved runs-rules illustrate that the improved runs-rules are superior in performance for large shifts in the process, while maintaining the same sensitivity in the detection of small shifts.
Further analysis of intensity fluctuations from a 3252-km acoustic propagation experiment in the eastern North Pacific Ocean

In the Acoustic Thermometry of Ocean Climate (ATOC) program’s Acoustic Engineering Test (AET), broadband 75-Hz center frequency transmissions were recorded on a 700-m-long vertical array, 3252 km distant from a midwater source suspended from R/P FLIP. The transmissions occurred over a 6-day period. Previously reported results from the AET using 12.7-min averaged data by Colosi et al. [J. Acoust. Soc. Am. 105(6), 3202–3218 (1999)], hereafter referred to as Colosi99) revealed surprisingly weak acoustic scattering for early arriving identifiable wavefronts. Colosi99 found pulse time spreads on the order of 0–5 ms and the probability density function (PDF) of peak intensity was close to log normal. In this paper these results are confirmed using 1.8-min averaged data. It is also shown that scintillation index (SI) is a strong function of position along the pulse with the smallest values occurring at the peak and larger values occurring at the tails. Intensity PDFs of identifiable wavefronts are reanalyzed in .
Passivity-based formation control of autonomous underwater vehicles

This study addresses the problem of steering a group of autonomous underwater vehicles along specified paths while keeping a desired spatial formation. The authors show how passivity-based techniques and consensus tracking theories are brought together to yield a distributed control strategy, by which the problems existing in current literature that a common reference velocity signal being available to all cooperating vehicles are explicitly extended. The desired coordinated behaviour is achieved by means of consensus on the velocity of path parameter of a virtual dynamic leader. The stability of the overall closed-loop system is analysed mathematically by adopting nested Matrosov theorem. To demonstrate the controller proposed, simulations results are presented and discussed.
Elements of finite order in free product sixth-groups

A free product sixth-group (FPS-group) is, roughly speaking, a free product of groups with a number of additional defining relators, where, if two of these relators have a subword in common, then the length of this subword is less than one sixth of the lengths of either of the two relators. Britton [1,2] has proved a general algebraic result for FPS-groups and has used this result in a discussion of the word problem for such groups.
Mean square stabilizability of continuous-time linear systems with partial information on the Markovian jump parameters

We provide necessary and sufficient conditions for mean square (MS) stabilizability of continuous-time linear systems with Markovian jumps in the parameters subject to the partial information on this jump variable. We assume that the Markovian jump parameter is not exactly known, but instead an estimate of it is available to the controller. Under some additional assumptions, a solution via linear matrix inequality is also provided. The results apply, in a unified basis, to the homogeneous case and two scenarios regarding additive disturbances: the one in which the system is driven by a Wiener process, and the one characterized by functions in L/sub 2//sup m/(R/sup +/), which is the usual scenario for the H/sub /spl infin// approach. It is also shown that MS stabilizability is equivalent to L/sub 2//sup n/ stabilizability whenever the disturbances are in L/sub 2//sup m/(R/sup +/).
Evaluation of the Autoparametric Pendulum Vibration Absorber for a Duffing System

In this work we study the frequency and dynamic response of a damped Duffing system attached to a parametrically excited pendulum vibration absorber. The multiple scales method is applied to get the autoparametric resonance conditions and the results are compared with a similar application of a pendulum absorber for a linear primary system. The approximate frequency analysis reveals that the nonlinear dynamics of the externally excited system are suppressed by the pendulum absorber and, under this condition, the primary Duffing system yields a time response almost equivalent to that obtained for a linear primary system, although the absorber frequency response is drastically modified and affected by the cubic stiffness, thus modifying the jumps defined by the fixed points. In the absorber frequency response can be appreciated a good absorption capability for certain ranges of nonlinear stiffness and the internal coupling is maintained by the existing damping between the pendulum and the primary system. Moreover, the stability of the coupled system is also affected by some extra fixed points introduced by the cubic stiffness, which is illustrated with several amplitude-force responses. Some numerical simulations of the approximate frequency responses and dynamic behavior are performed to show the steady-state and transient responses.
Über arithmetische assoziierte ordnungen

Zusammenfassung Letpbe an odd rational prime, andL/Ka totally ramified finite abelian extension ofp-adic fields. LetGdenote the Galois group ofL/K. For each idealIof the valuation ring ofLwe study its “associated order”End Q p[G](I) with respect to Q p[G]. This order is a natural operating ring for the idealI, and is an important invariant of its Z p[G]-structure. We show that unlessGis cyclic no such order can contain any idempotent of Q p[G] which does not already lie in Z p[G] This is a strong restriction on the possible structures of arithmetical associated orders. We also describe an algorithm for the explicit computation of associated orders which can in many cases be implemented effectively on a computer. In this way we are able to compute explicit examples of arithmetical associated orders which falsify a conjecture previously made by the second named author.
Study of Electronegative Ar/O2 Discharge by Means of Langmuir Probe

The paper presents systematic Langmuir probe diagnostic of a dc discharge in Ar/O2 mixture with low fraction of O2, burning in a sputtering planar magnetron. Electron density, electron temperature and plasma potential are investigated in dependence upon experimental conditions like pressure, rate of oxygen, incoming power, and on balanced or unbalanced mode of magnetron. A new method of determining negative‐ion density from the current‐voltage characteristic is proposed. This method is based on comparison of the characteristic measured in electronegative plasma (e.g. Ar/O2) with a reference characteristic scanned in an electropositive counterpart (Ar), existing in similar conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhanced mechanical properties and large magnetocaloric effects in bonded La(Fe, Si)(13)-based magnetic refrigeration materials

Bonded La(Fe, Si)13 magnetic refrigeration materials have been prepared, and the microstructure, mechanical properties, and magnetocaloric effect (MCE) of bonded LaFe11.7Si1. 3C0.2Hx have been investigated systematically. Bonded materials show porous architecture, and the mechanical properties increase with the increase of epoxy resin content, which could fill more pores and boundaries and thus enhance the binding force between different particles. Bonded LaFe11.7Si1. 3C0.2H1. 8 with 3 wt. % epoxy resin exhibits a compressive strength of 162 MPa, 35% higher than that of bulk compound. The mass magnetic entropy change (ΔSM) remains nearly unchanged while the volumetric ΔSM reduces due to the decrease of density in bonded materials. For a low magnetic field change of 2 T, the maximum ΔSM value of bonded LaFe11.7Si1. 3C0.2H1. 8 is ∼10.2 J/kg K and ∼54.7 mJ/cm3 K, which is larger than those of some magnetocaloric materials in the same temperature range. Enhanced mechanical properties and great MCE suggest that bon.
Magnesium sulphate optimises surgical field without attenuation of the stapaedius reflex in paediatric cochlear implant surgery

Background and Aims: The anaesthesia technique for paediatric cochlear implantation should be modified to achieve an optimised surgical field and allow neuromonitoring. Total intravenous anaesthesia (TIVA) provides good surgical condition without affecting intraoperative electrical stapaedial reflex threshold (ESRT). Though magnesium sulphate (MgSO4) is a cheap, readily available drug for controlled hypotension, it can decrease the amplitude of motor-evoked potentials. This study aimed to evaluate the effect of MgSO4 infusion on quality of surgical field, intraoperative ESRT, and anaesthetic requirements in paediatric cochlear implant surgery performed under TIVA. Methods: In this randomised controlled trial, 66 children (1-6 years) undergoing cochlear implant under TIVA were randomly assigned to control group or MgSO4 group. The primary outcome was quality of surgical field, and the secondary outcomes were mean arterial blood pressure (MAP), heart rate (HR), ESRT, and the intraoperative anaesthetic requirements. The incidence of adverse events was recorded as well. Results: The quality of surgical field was better in group M than group C, P < 0.02. The number of children who achieved optimum surgical conditions (scores ≤2) was significantly better in the group M (n = 23/33, 70%) compared with group C (n = 13/33, 39%), P < 0.001. MAP, HR, and anaesthetic requirements were significantly lower in group M, P < 0.05. There were no differences between both groups regarding ESRT response. Conclusion: Magnesium sulphate IV infusion optimised surgical field and decreased anaesthetic requirements without attenuating the ESRT in paediatric cochlear implant surgery performed under TIVA.
Simultaneous Inference for HIV Dynamic Models with Skew-t Distribution Incorporating Mismeasured Covariate and Multiple Treatment Factors

It is a common practice to analyze AIDS longitudinal data using nonlinear mixed-effects (NLME) models with normal distribution for HIV dynamics. Normality of model errors may unrealistically obscure important features of subject variations. To partially explain between- and within-subject variations, covariates are usually introduced in such models; some covariates, however, may be often measured with substantial errors. This article, motivated by an AIDS clinical study, discusses a Bayesian NLME joint modeling approach to viral dynamic models with skew-t distribution in the presence of covariate measurement error. In this model, we fully integrate viral load response, time-varying CD4 covariate with measurement error, and time-dependent drug efficacy, which is a function of multiple treatment factors, into the data analysis. Thus, the purpose of this article is to demonstrate our models and methods with application to an AIDS clinical trial study. The results suggest that modeling HIV dynamics and virologic responses with consideration of covariate measurement error and time-varying clinical factors may be important for HIV/AIDS studies in providing quantitative guidance to better understand the virologic responses to antiretroviral treatment and to help evaluation of clinical trial design in existing therapies.
Laminar–turbulent transition in pipe flow for Newtonian and non-Newtonian fluids

A cylindrical pipe facility with a length of 32 m and a diameter of 40 mm has been designed. The natural transition Reynolds number, i.e. the Reynolds number at which transition occurs as a result of non-forced, natural disturbances, is approximately 60 000. In this facility we have studied the stability of cylindrical pipe flow to imposed disturbances. The disturbance consists of periodic suction and injection of fluid from a slit over the whole circumference in the pipe wall. The injection and suction are equal in magnitude and each distributed over half the circumference so that the disturbance is divergence free. The amplitude and frequency can be varied over a wide range. First, we consider a Newtonian fluid, water in our case. From the observations we compute the critical disturbance velocity, which is the smallest disturbance at a given Reynolds number for which transition occurs. For large wavenumbers, i.e. large frequencies, the dimensionless critical disturbance velocity scales according to Re−1, while for small wavenumbers, i.e. small frequencies, it scales as Re−2/3. The latter is in agreement with weak nonlinear stability theory. For Reynolds numbers above 30 000 multiple transition points are found which means that increasing the disturbance velocity at constant dimensionless wavenumber leads to the following course of events. First, the flow changes from laminar to turbulent at the critical disturbance velocity; subsequently at a higher value of the disturbance it returns back to laminar and at still larger disturbance velocities the flow again becomes turbulent. Secondly, we have carried out stability measurements for (non-Newtonian) dilute polymer solutions. The results show that the polymers reduce in general the natural transition Reynolds number. The cause of this reduction remains unclear, but a possible explanation may be related to a destabilizing effect of the elasticity on the developing boundary layers in the entry region of the flow. At the same time the polymers have a stabilizing effect with respect to the forced disturbances, namely the critical disturbance velocity for the polymer solutions is larger than for water. The stabilization is stronger for fresh polymer solutions and it is also larger when the polymers adopt a more extended conformation. A delay in transition has been only found for extended fresh polymers where delay means an increase of the critical Reynolds number, i.e. the number below which the flow remains laminar at any imposed disturbance.
Wald's Test as Applied to Hypotheses in Logit Analysis

Abstract For tests of a single parameter in the binomial logit model, Wald's test is shown to behave in an aberrant manner. In particular, the test statistic decreases to zero as the distance between the parameter estimate and null value increases, and the power of the test, based on its large-sample distribution, decreases to the significance level for alternatives sufficiently far from the null value.
Well-posedness of 3D vortex sheets with surface tension

We prove well-posedness for the initial value problem for a vortex sheet in 3D fluids, in the presence of surface tension. We first reformulate the problem by making a favorable choice of variables and parameterizations. We then perform energy estimates for the evolution equations. It is important to note that the Kelvin-Helmholtz instability is present for the vortex sheet in the absence of surface tension. Accordingly, we must construct the energy functional carefully with an eye toward the regularization of this instability. Well-posedness follows from the estimates.
Numerical simulation of thermal blooming effect of laser propagation in atmosphere

This paper analyzes the effects of thermal blooming on the Far-Field Irradiance Distribution, based upon the steady-state thermal blooming model, which is introduced by Wallace. It uses the method of numerical simulation and gives the relativity between thermal blooming and these parameters, including initial power,the radius and wavelength. The result reveals that a new void dimensional parameter can describe the extent of thermal blooming. When this dimensional parameter decreases, thermal blooming effect becomes more serious. The result can provide theoretic analysis of thermal blooming effect on the Far-Field. In addition, when the wavelength or the radius changes, the result of Wallace model does not accord with the fact. The contradiction reveals the shortcoming of this model.
GAIN MARGINS AND PHASE MARGINS FOR MULTIVARIABLE CONTROL-SYSTEMS WITH ADJUSTABLE-PARAMETERS

Abstract This paper presents a method for finding the boundaries of gain margins and phase margins of multivariable control systems with adjustable parameters. The considered systems are first decomposed into the augmented open-loop transfer functions modified by adding an analytical gain-phase margin tester, then the characteristic equations are formulated, and finally the stability equations are used to find the boundaries of constant gain margins and phase margins. The main advantage of the proposed method is to obtain complete information about the effects of adjustable parameters on gain margins and phase margins; thus it is a useful tool for analysis and design of robust control systems,
Tests of Independence and Zero Correlations Among P Random Variables

Suppose it is desired to determine whether there is an association between any pair of p random variables. A common approach is to test H0 : R = I, where R is the usual population correlation matrix. A closely related approach is to test H0 : Rpb = I, where Rpb is the matrix of percentage bend correlations. In so far as type I errors are a concern, at a minimum any test of H0 should have a type I error probability close to the nominal level when all pairs of random variables are independent. Currently, the Gupta‐Rathie method is relatively successful at controlling the probability of a type I error when testing H0: R = I, but as illustrated in this paper, it can fail when sampling from nonnormal distributions. The main goal in this paper is to describe a new test of H0: Rpb = I that continues to give reasonable control over the probability of a type I error in the situations where the Gupta‐Rathie method fails. Even under normality, the new method has advantages when the sample size is small relative to p. Moreover, when there is dependence, but all correlations are equal to zero, the new method continues to give good control over the probability of a type I error while the Gupta‐Rathie method does not. The paper also reports simulation results on a bootstrap confidence interval for the percentage bend correlation.
FLUXOID QUANTIZATION, PAIR SYMMETRY, AND THE GAP ENERGY IN THE CURRENT- CARRYING BARDEEN-COOPER-SCHRIEFFER STATE

The method of Byers and Yang is extended for application to the current- carrying BCS state by including the magnetic interaction between electrons in the zero-order Hamiltonian. In the case of a thin superconducting ring, the problem is reduced to the zero-current problem by separating out the collective motion. In the general case, this process is not carried out completely, but the symmetry of the BCS state provides enough information to obtain the desired results. When the fluxoid is equal to an integral multiple of ( pi hc/e), the single-particle states occur in pairs which go into each other under reflection about the average electron velocity at each point. A qualitative argument is given to show why this symmetry is necessary for the BCS reduced interaction to have its full effectiveness. The crux of the matter is that in the absence of such symmetry, the Fermi surface is irregular and a substantial fraction of the important states near that surface are unable to participate in a coherent BCS wave function. The Meissner effect is not necessary for the quantization of magnetic flux. (auth)
Accretion Disks around T Tauri Stars

The extent to which the continuum spectral energy distributions of T Tauri stars from 0.2 to 10 microns can be explained by a simple model consisting of an active PMS star and active accretion disk is considered. The disk contributes both an IR excess due to accretion energy dissipation and stellar light reprocessing and an ultraviolet excess from the boundary layer between disk and star where half of the total accretion luminosity is generated. This model is shown to be good at predicting the range of continuum excesses observed in T Tauri stars, with accretion rates implied up to a few times 10 to the -7th solar mass/yr. 83 references.
Pair Correlation of Zeros, Primes in Short Intervals and Exponential Sums over Primes

)and#, #$ run over the imaginary part of the non-trivial zeros of the Riemann zeta function. In view of the above results, wemay therefore expect that the quantities R(X, ! ), J(X, h) and F(X, T) areclosely related.In fact, Goldston and Montgomery [5] proved that determining theasymptotic behavior of J(X, h)orofF(X, T), as X˜ and h or T insuitable ranges, are, under the Riemann Hypothesis (RH), equivalentproblems. Our first goal is to show that such an equivalence can beextended to R(X, ! ) as well. We haveTheorem 1. Assume RH. As X˜, the following statements areequivalent:(i) for every =>0, R(X, ! )t2X! log X! uniformly for X