Miracle-dz/UniFAR-FTUs huggingface dataset:
Simple formula for current on a cylindrical receiving antenna

An approximate formula is presented for the induced current on a loaded (or unloaded) thin cylindrical receiving antenna which is illuminated by an incident plane wave from an arbitrary direction. This formula involves only elementary functions and therefore can be calculated easily. Its derivation is based on the multiple reflection approach originated by Weinstein, Shen, and others. Currents calculated by the present formula are found to be in good agreement with experimental data.
Group-velocity dispersion measurements in a photonic bandgap fiber

Spectral interferometry with a supercontinuum is used for the first experimental measurement, to our knowledge, of phase dispersion of the fundamental mode in multiple bandgaps of a photonic bandgap fiber. The dispersion data show a strong influence of the Bragg scattering from the crystal structure surrounding the core. A simple two-dimensional model that includes the effects of a wavelength-dependent angle of propagation, where the angle is determined by the Bragg-scattering condition, and the effects of thin-film-like resonant scattering planes in the fiber is found to explain the observations qualitatively.
Anisotropic magnetoresistance and anomalous Hall effect in manganite thin films

We report on anisotropic magnetoresistance (AMR) and Hall effect measurements along the and [001] directions in a (110)-oriented La2/3Ca1/3MnO3 thin film. While the electrical resistivity and the ordinary Hall coefficient are smaller for I along [001], evidencing some anisotropy of the Fermi surface, both the AMR and the anomalous Hall coefficient are larger when the current is applied along . Since these two phenomena originate from spin–orbit coupling effects, we state that our results support an anisotropy of the spin–orbit interaction in manganites. The possible origin of this anisotropy is discussed.
DEVELOPMENT OF A CURRENT SHEET IN THE WAKE OF A FAST CORONAL MASS EJECTION

A bright ray that developed in the wake of a fast coronal mass ejection (CME) on 2005 September 7 presents a unique opportunity to study the early development and physical characteristics of a reconnecting current sheet (CS). Polarization brightness images from the Mk4 K-Coronameter at the Mauna Loa Solar Observatory are used to determine the structure of the ray along its axis low in the corona as it progressed outward. Coverage of the early development of the ray out to ∼1.3 R☉ for a period of ∼27 hr after the start of the event enables for the first time in white light a measurement of a CME CS from the top of the arcade to the base of the flux rope. Measured widths of the ray are combined to obtain the kinematics of the upper and lower “Y”-points described in reconnection flux-rope models such as that of Lin & Forbes. The time dependence of these points are used to derive values for the speed and acceleration of the growth of the CS. We note the appearance of a large structure which increases in size as it expands outward in the early development of the ray and an apparent oscillation with a period of ∼0.5 hr in the position angle of the ray.
Time-dependent Flare Signature in Hydrogen Balmer Lines

In recent studies of Hα flare imaging spectroscopy performed by Leka et al. and de la Beaujardière et al. in 1993, Hα line profiles have been investigated as a function of space to locate the physical process underlying observed spectral profiles. In this Letter, we discuss time evolution of hydrogen Balmer line profiles at a fixed spatial point recorded by the multichannel spectrograph at Nanjing University in China during the 1991 October 27 white-light flare which occurred in NOAA 6891. It is found that the Balmer emission lines with a central reversal show up at the beginning of the Hα flare but change to single-peaked profiles in about 30 s. This result may, according to Canfield et al.'s model in 1993, indicate that the Balmer line enhancement even at one flare site could be caused by two physical processes, namely, initially by the high-energy particle precipitation and subsequently by the high coronal pressure. We also present evidence for downward motion and the Stark broadening effect on the observed Balmer line wings to examine further the physical consequences of the particle precipitation. Time correlation of the Balmer line emission with hard X-ray and continuum brightening is briefly discussed based on the spectral information.
Evaluatiok of optimum weights and average run lenghts in ewma control schemes

In this paper, a two sided exponentially weighted moving average (EWMA) control scheme of Roberts (1959) is studied. By using a continuous time model, explicit formulae for the average run lengths are obtained. Using these results, a formula for the optimal weight in the EWMA is obtained by minimizing the out of control average run length for a given reference value and in control average run length [ARL 0), which is assumed to be large. These optimunl weights are found to be very close to the optimum weights obtained by Lucas and Saccucci(1990) for the discrete time model using the Markov chain method. It is shown that the EWMA scheme performs almost as well as the CUSUM for moderate ARLO. Another important finding that emerges from this study is that the EWMA scheme is less sensitive to the choice of a reference value as compared to the CUSIJM. We also provide very accurate formulae for the ARL O and ARL μ of the two-sided CUSUM procedure.
Depth‐integrated free‐surface flow with a two‐layer non‐hydrostatic formulation

This paper presents the derivation of a depth‐integrated wave propagation and runup model from a system of governing equations for two‐layer non‐hydrostatic flows. The governing equations are transformed into an equivalent, depth‐integrated system, which separately describes the flux‐dominated and dispersion‐dominated processes. The depth‐integrated system reproduces the linear dispersion relation within a 5 error for water depth parameter up to kd = 11, while allowing direct implementation of a momentum conservation scheme to model wave breaking and a moving‐waterline technique for runup calculation. A staggered finite‐difference scheme discretizes the governing equations in the horizontal dimension and the Keller box scheme reconstructs the non‐hydrostatic terms in the vertical direction. An semi‐implicit scheme integrates the depth‐integrated flow in time with the non‐hydrostatic pressure determined from a Poisson‐type equation. The model is verified with solitary wave propagation in a channel of uniform depth and validated with previous laboratory experiments for wave transformation over a submerged bar, a plane beach, and fringing reefs. Copyright © 2011 John Wiley & Sons, Ltd.
Quiet time densities of hot ions at geosynchronous orbit

Densities of hot (100 eV{endash}40 keV) ions vary with local time at geosynchronous orbit. Typically, the density is maximum near midnight, falls off toward both terminators, and is minimum near noon. This local time dependence is routinely observed in the Los Alamos geosynchronous plasma data. We use a month of these data (June 1996) and a simple model of particle drifts within the magnetosphere to explore its origins. We first show that the nightside density profile is shaped according to the drift path topology: trapped orbits are depleted, and only particles drifting on open trajectories contribute to this population, particularly for observations taken at times of low K{sub p}. Then, we highlight spectral absorption in dayside fluxes, which occurs when the particles pass through the geocorona. A model of charge exchange accounts for the shape and energy range of the absorption signatures observed at low K{sub p} for varying pitch angles. The density absorption computed versus local time matches the observations. Hence these basic principles of particle motion in the terrestrial magnetosphere readily explain the local time dependence of the hot ion density at geosynchronous orbit. {copyright} 1998 American Geophysical Union
The effect of surface stress on an interface crack in linearly elastic materials

We consider an interface crack whose crack faces are coated with a thin reinforcing film of separate elastic material. We obtain asymptotic solutions, which, in the case of plane elasticity, demonstrate that the addition of the thin film effectively eliminates the well-known oscillatory behavior of the displacement and stress fields in the vicinity of the crack tip leading to a strong square-root stress singularity. In the case of anti-plane elasticity, the effect of the reinforcement is to reduce the order of the stress singularity at the crack tip. In addition, we demonstrate that the reinforcement induces a displacement field which is smooth locally and bounded at the crack tip.
Small-scale variation of convected quantities like temperature in turbulent fluid Part 2. The case of large conductivity

The analysis reported in Part 1 is extended here to the case in which the conductivity κ is large compared with the viscosity ν, the conduction ‘cut-off’ to the θ-spectrum then being at wave-number (ε/κ3)¼. It is shown, with a plausible and consistent hypothesis, that the convective supply of $\overline {\theta^2}$-stuff to Fourier components of θ with wave-numbers n in the range (ε/κ3)¼ [Lt ] n [Gt ] (ε/ν3)¼ is due primarily to motion on a length scale of order n-1 acting on a uniform gradient of θ of magnitude $[(\overline {\nabla \theta)^2}]^{\frac {1}{2}}$. The consequent form of the theta;-spectrum within this same wave-number range is $\Gamma (n) = \frac {1}{3}C \chi \epsilon ^{\frac {2}{3}} k^{-3}n^ {-\frac {17} {3}}. $ The way in which conduction influences (and restricts) the effect of convection on the distribution of θ at these wave-numbers beyond the conduction cut-off is discussed.
The Homicidal Chauffeur

P differential games had their beginning in the pioneering work of Isaacs. These differential games are a generalization of the optimal guidance problem, in the sense that guidance strategies are to be found for each of two players having conflicting objectives. The players' strategies, respectively, are found to minimize and to maximize a specific criterion, which is often taken to be the time to termination, or "capture. " The second-order differential equations describing the dynamics of the homicidal chauffeur game include two parameters, which are the speed ratio and the ratio of capture-radius to pursuer's minimum-turn radius. It is the purpose of this paper to show that this apparently simple, physically motivated differential game can lead to novel and remarkably complex solutions. It is shown that the classical necessary conditions often fall far short of providing the complete solution to the problem. On the contrary, a variety of "exceptional" lines are found to occur in the state space of the game. These lines are not predicted by the theory and they are of fundamental importance, since they separate regions of differing optimal strategies for either or both of the players. Isaacs discovered the barrier, universal line (singular arc), equivocal line, and a pursuer's dispersal line in his study of the problem. Other types of lines are found to include new dispersal lines, switch lines, switch envelopes, focal lines, and safe-contact motion. The switch envelope and focal line phenomena are believed to be new to the general theory of differential games.
Pulsed electromagnetic radiation from a line source in a two‐media configuration

The pulsed electromagnetic radiation from a two-dimensional line source in a lossless two-media configuration is investigated theoretically. The author's modification of Cagniard's technique is used to derive closed-form expressions for the electromagnetic field components anywhere in the configuration. Numerical results are presented pertaining to the incident, the reflected, and the transmitted wave for different positions of the source and the observer, as well as for different contrasts of the two media. Also, the corresponding total-field plots are shown. In an appendix, the modified Cagniard contours pertaining to a lossless N-media configuration are discussed and some two-media modified Cagniard contours are shown.
Bond-orbital model for second-order susceptibilities

The bond-orbital model (BOM) for tetrahedral compounds is used self-consistently to calculate the second-order susceptibility. No adjustable parameters are used and agreement with experiment is good. The origin of the nonlinearity arises from a charge transfer as a result of the asymmetric polar energy between the anion and the cation. The model correctly predicts an optimum polarity to maximize second-order susceptibilities.
Two definitions of fractional dimension

The main properties of the Hausdorff dimension, here denoted by dim, are In ℝp, in variance under a group Н of homeomorphisms: ∀HεH, dim О H = dim. The definition of H, introduced in (15) and (16), is recalled in § 2.
Spindynamics in thulium van Vleck paramagnets

Three different thulium hydrides (TmH2, Tm0.06La0. 94H2, TmH2.73 have been investigated by means of nuclear magnetic resonance and static magnetic susceptibility measurements in a temperature range 4–300 K. A careful analysis of the data facilitates the determination of the various crystal field splittings and the type of microscopic magnetic interactions among and between the nuclear subsystems as well as those with the electrons. The selection of the samples used was made in order to clarify a transversal relaxation maximum of the protons at about 35 K. The measured relaxation rates and the resonance positions will be compared to theoretical results obtained by computing the relevant electronic and nuclear spectral densities as function of temperature.
On the adele rings and zeta-functions of algebraic number fields

Throughout this paper Q and Z denote the rational number field and the rational integer ring, respectively. An algebraic number field always means an algebraic number field of finite degree, an integer means a rational integer and a prime number means a rational prime number. For an algebraic number field k, we denote by kA the adele ring of k, by ζ^(s) the Dedekind zeta-f unction of k and Ok the integer ring of k. For any prime ideal p of k, k$ denotes the completion of k by p-adic valuation, for real place p of kt k$ denotes the real number field and for imaginary place p of k, k$ denotes the complex number field. We write Nk/Q for the norm of an ideal in k. For a Galois extension L of a field F, we denote by Gal(L/F] the Galois group of L/F. For a set S, we denote by card (S) the cardinarity of S. We write [G H~] for the index of a subgroup H in a finite group G. The word "isomorphism" for topological groups, toplogical rings and topological fields, means a topological isomorphism. The main purpose of this paper is to prove the following theorem, which is a refinement of our previous paper [4] : THEOREM. Let m be a square free integer such that m^±l, ±2, and n an integer such that n^3. Put k=Q(^m) and k'=Q(V~2Xψm\ If
Time-dependent modelling of PKS 2155-304 in a low state: one- or two-zone emission modelling?

One-zone radiation models have been widely used in modelling the steady-state multiwavelength (MW) spectra of blazars, having as main goal the determination of the physical conditions in the emitting region, such as the magnetic field strength, the species of radiating particles etc. Then, the results from one- zone stationary modelling are often used as a stepping stone for studying flaring events. Here we show that the application of steady-state one-zone models on intrinsic variable sources, even when these are in a low state, can be misleading. Although the one-zone SSC and proton synchrotron models succeed in fitting the time-averaged MW spectrum, they cannot easily (or at all) reproduce the small amplitude multifrequency variability. We show that a two-component leptonic model addresses both spectral and temporal observations more successfully, albeit at the expense of more free parameters.
Free space optical communications research at the U.S. Naval Research Laboratory

Free space optical (FSO) communication has enjoyed a renewal of interest in the past decade driven by increasing data rate requirements and decreasing amounts of radio frequency spectrum. These needs exist in both the commercial and military sectors. However military communications requirements differ in other ways. At the U.S. Naval Research Laboratory (NRL) we have been conducting research on FSO communications for over ten years with an emphasis on tactical applications. NRL's FSO research has covered propagation studies in the maritime domain, new component development, and systems demonstrations. In addition NRL has developed both conventional, direct, laser communications systems and retro-reflecting systems. In this paper we review some of this work and discuss possible future applications of FSO communications.
An Error Minimization Method in Adaptive Control

THIS paper presents a design approach based on error minimization in adaptive control for improving the rate of adaptation and allowing under certain conditions exponential convergence of the error dynamics. Global stability results are given for the case of perfectly parameterized uncertainty. The approach relies on the fact that the unknown weights in any linearly parameterized representation of uncertainty satisfy an integral equation involving the state and control variables. The equation is used to formulate an error minimization problem, the solution for which can be incorporated in the adaptive law. The paper extends an idea originally developed in (1) for the case of scalar uncertainty to the vector case. The results are conceptually similar to the notion of composite adaptation (2), and techniques developed for state estimation (3). The main difference is that these approaches use different signals. The effect of the modified adaptive components is illustrated on a dynamical model of an aircraft in which uncertainty is present both in control effectiveness and non-linear state dependent terms.
VLBA polarization observations of BL Lac objects and passive elliptical galaxies

We present Very Long Baseline Array (VLBA) 5-GHz polarimetric observations of 23 BL Lacertae (BL Lac) objects and radio galaxies selected from the 200-mJy sample. BL Lac objects have core polarization values lower than those found in previous samples. The magnetic field geometry in the jets is not unique: both parallel and perpendicular geometries are observed, even in the same sources. The parsec-scale morphology of radio galaxies is clearly divided in two classes: one-sided core-jet sources, which show polarized emission in the core and/or jet, and two-sided symmetric objects which are not polarized. We discuss and compare the parsec-scale polarization properties of the radio cores and jets for the BL Lac objects and the radio galaxies in relation to their parsec-scale morphology and high-frequency integrated spectral index.
Ne II 12.8 micron emission from the galactic center. II

Recent observations of the 12.8-micron Ne II emission from the galactic center have revealed a region of primarily blueshifted emission in addition to the previously detected redshifted emission. It appears most likely that the blueshifted and redshifted emission come from separate clouds and that the dynamics of the ionized gas is dominated by the gravitational potential of the massive core at the galactic center. On the basis of the velocities and velocity dispersions, the total mass within a radius of 1 pc about the galactic center is estimated to be of the order of 4 million solar masses.
Magnetic tunnel junction field sensors with hard-axis bias field

We have fabricated and studied the magnetic properties of the Ni81Fe19/Al2O3/Ni81Fe19 based magnetic tunnel junction sensors. Magnetoresistance (MR) of 35% is achieved with a small applied field (<10 Oe). The introduction of a hard axis bias field linearizes the MR response. The hysteresis disappears in hard-axis fields greater than 3 Oe, which corresponds to the effective anisotropy field along the easy axis. A sensitivity of 3.5%/Oe has been demonstrated in this linear region. Low-frequency noise measurements indicate that sensor noise is dominated by field-dependent 1/f noise caused by magnetization fluctuations. Finally, a noise level as low as 1 nT/Hz1/2 has been obtained.
The Statistics Teaching Inventory: A Survey on Statistics Teachers' Classroom Practices and Beliefs

This paper reports on an instrument designed to assess the practices and beliefs of instructors of introductory statistics courses across the disciplines. Funded by a grant from the National Science Foundation, this project developed, piloted, and gathered validity evidence for the Statistics Teaching Inventory (STI). The instrument consists of 50 items in six parts and is administered online. The development of the instrument and the gathering and analysis of validity evidence are described. Plans and suggestions for use of the STI are offered.
Friction in unsteady open-channel flow over gravel beds

A study on the friction in unsteady open-channel flow over gravel beds is presented in this paper. Different hydrographs (Table 1) were experimentally investigated. The friction velocity was determined using the equation of mot ion (equation 1). The unsteadiness of the flow was expressed with thedimensionlessClauser parameter (equation 17). It is shown that for a given hydrograph the friction velocity, u *SV is usually larger in the rising branch (accelerating flow) than in the falling branch (decelerating flow), as can be seen in Fig. 3; it reaches its maximum value before the arrival of the peak (D = D max) of the hydrograph. During the passage of a hydrograph, the friction coefficient, f is usually larger in the rising branch and smaller in the falling branch; the descending tendency of the f-value in the rising branch is usually followed by a less pronounced ascending one in the falling branch (Fig. 7). The findings on the friction coefficient, f, could be used to understand the field data reported in.
An empirical method for estimating long‐wave radiation exchanges in the British Isles

From radiation measurements at Kew Observatory (tabulated by Lonnqvist), the effective emissivity of the atmosphere e, defined as the ratio of incoming long-wave radiation to black-body radiation at screen temperature, can be related to optical path m (cm) by With standard deviation ± 0·018. The relation between m and surface vapour pressure e (mb) found from Belasco's (1952) air mass analysis is giving almost the same as Brunt's equation from Benson data. Net long-wave radiation L over short grass can be calculated from where c is fractional cloudiness; σTA is black-body radiation at screen temperature; ΔL1 is a correction for the difference between TA and cloud-base temperature; and ΔL2 for the difference between TA and surface radiative temperature. From Roach's Kew data, ΔL1 = – 18 cal cm−2 day−1 and ΔL2 varies with season from – 12 cal cm−2 day−1 (December) to + 20 cal cm−2 day−1 (June). Throughout the British Isles, annual mean L with c = 0 is close to – 200 cal cm−2 day−1, and for real values of c Estimated annual net (total) radiation is 29 k cal cm−2 with little variation over the British Isles.