Miracle-dz/UniFAR-FTUs huggingface dataset:
Thermal-recovery of modal instability in rod fiber amplifiers

We investigate the temporal dynamics of Modal instabilities (MI) in ROD fiber amplifiers using a 100 μm core rod fiber in a single-pass amplifier configuration, and we achieve ~200W of extracted output power before the onset of MI. Above the MI threshold, we investigate the temporal dynamics of beam fluctuations in both the transient and chaotic regime. We identify a set of discrete frequencies in the transient regime and a white distribution of frequencies in the chaotic regime. We test three identical rods using a multiple ramp-up procedure, where each rod is tested in three test series and thermally annealed between each test series. We find that the MI threshold degrades as it is reached multiple times, but is recovered by thermal annealing. We also find that the test history of the rods affects the temporal dynamics.
A New Type of Control Chart Limits for Means, Ranges, and Sequential Runs

Abstract Since most conventional control chart limits are designed so that the ratio of the expected number of false alarms to the number of samples tested is fixed in advance irrespective of the sample size, the ratio of false alarms to the number of articles tested varies with the sample size. In this paper, control charts are designed for which the expected ratio of false alarms to the number of articles tested is independent of the sample size. The power of the control charts in relation to sample size is investigated.
Spatial and temporal structures of impulsive bursts from solar flares observed in UV and hard X-rays

We present new observations of impulsive UV and hard X-rays bursts in two solar flares obtained with instruments on Solar Maximum Mission. The UV bursts were observed in the Si IV and O IV emission lines, whose intensity ratio is density-sensitive. By comparing the spatially resolved Si IV/O IV observations with the corresponding hard X-ray observations, we are able to study their spatial and temporal relationships. For one flare, the individual component spikes in the multiply peaked hard X-ray burst can be identified with different discrete Si IV/O IV flaring kernels of size 4'' x 4'' or smaller, which brighten up sequentially in time. For the other, many Si IV/O IV kernels, widely distributed over a large area, show impulsive bursts at the same time, which correlate with the main peak of the impulsive hard X-ray burst. The density of the flaring Si IV/O IV kernals is in the range from 5 x 10/sup 12/ to 10/sup 13/ cm/sup -3/.
Introducing simple harmonic motion

Simple harmonic motion is an important topic for physics students and has wide applications in the world around us. A clear introduction to the subject is therefore vital. This article stresses the need for a good description of the phenomenon and uses the device of the auxiliary circle to help show the key relationships between acceleration, displacement, time, velocity and phase.
Stellar parameters and evidence of circumstellar activity for a sample of Herbig Ae/Be stars

Aims. We investigate evidence of accretion in a sample of 15 Herbig Ae/Be stars to determine whether these events originate in a remnant gaseous structure from the primordial cloud (rich in hydrogen) or in a metal-rich body (like comets in our Solar System). During such analysis we also determine precise stellar parameters for this sample of stars. Methods. The stars were observed using high resolution spectroscopy ($R = 48\,000$). A synthetic photospheric spectrum was constructed and then subtracted from the observed one to obtain the circumstellar component. An iterative procedure was applied to find the stellar parameters that were used to build the synthetic photospheric spectrum. Results. Evidence of circumstellar activity were found in four stars: HD 100546, HD 142666, HD 144432 and HD 145718. The presence of redshifted absorption features only in the Balmer lines implies that the accreting material is hydrogen-rich, excluding the possibility that the accretion events might have been created by comet-like bodies. We determined effective temperature, surface gravity, metallicity and the projected rotational velocity for the stars in our sample.
Optimal L 1 -Rate of Convergence for The Viscosity Method and Monotone Scheme to Piecewise Constant Solutions with Shocks

We derive optimal error bounds for the viscosity method and monotone difference schemes to an initial-value problem of scalar conservation laws with initial data being a finite number of piecewise constants, subject to the initial discontinuities satisfying the entropy conditions. It is known that the entropy solution of the problem is piecewise constant with a finite number of interacting shocks satisfying the entropy conditions. A rigorous analysis shows that both the viscosity method and monotone schemes to approach the initial-value problem have uniform $L^1$-error bounds of $O(\epsilon)$ and $O(\Delta x)$ for the time $+\infty>t>0$, respectively, where $\epsilon$ and $\Delta x $ are their corresponding viscosity coefficient and discrete mesh length. The results are improvements over the half-order rates of $L^1$-convergence. Numerical experiments for the Lax--Friedrichs scheme are presented and numerical results justify the theoretical analysis.
Vibronic effects in the 1.4-eV optical center in diamond

We report optical absorption and luminescence measurements on the $1.4\text{\ensuremath{-}}\mathrm{eV}$ center in diamond. We show that the zero-phonon lines have a temperature-dependent Ni-isotope shift, that the isotopic shifts induced by carbon and nickel are opposite in sign, and that a local vibronic mode is present in the absorption spectrum but not in luminescence. The microscopic properties of the center are successfully analyzed with the Ludwig-Woodbury theory (LWT), revealing that the ${\mathrm{Ni}}^{+}$ ion in the $1.4\text{\ensuremath{-}}\mathrm{eV}$ center only weakly interacts with the diamond lattice. The importance of vibronic effects in the LWT analysis is experimentally demonstrated. It is believed that similar effects can account for the discrepancies previously encountered in modeling other $3{d}^{9}$ impurities in semiconductors.
Influence of the maximal fluctuation moment order q on multifractal records normalized by finite-size effects

We focus on the importance of q moments range used within the multifractal detrended fluctuation analysis (MFDFA), to calculate the generalized Hurst exponent spread and multifractal properties of signals. Different orders of detrending polynomials are also discussed. In particular, we analyze quantitatively the corrections to the spread of the generalized Hurst exponent profile . They allow to extend the previously found formulas describing the level of artificial multiscaling in finite signals for large q to an arbitrary narrower range of q moments used in MFDFA technique in distinct applications. Examples of the implementation of proposed corrections to real multifractal financial data are provided at the end.
Dense cores in dark clouds. IV: HC5N observations

We report detections or possible detections of the J = 9-8 rotational transition of HC/sub 5/N in 10 new dark cloud sources. All of the strong sources and most of the known sources are in Taurus. In contrast to maps of TMC-1, maps of NH/sub 3/ and HC/sub 5/N emission in L1544 and in TMC-1C show no relative shift of peak positions. Column densities of HC/sub 5/N and C/sup 18/O are roughly correlated, but N(HC/sub 5/N) increases faster than N(C/sup 18/O), suggesting that the abundance of HC/sub 5/N ranges from approx.10/sup -10/ in the weakest sources to approx.10/sup -9/ in the strongest sources. Comparison with predictions of chemical models indicates that this abundance variation is unlikely to be due to variations in cloud density, but it may be due to differences in the degree of chemical evolution from cloud to cloud. If so, TMC-1 is more evolved than L183.
A Bayesian analysis for the Block and Basu bivariate exponential distribution in the presence of covariates and censored data

In this paper, we introduce a Bayesian Analysis for the Block and Basu bivariate exponential distribution using Markov Chain Monte Carlo (MCMC) methods and considering lifetimes in presence of covariates and censored data. Posterior summaries of interest are obtained using the popular WinBUGS software. Numerical illustrations are introduced considering a medical data set related to the recurrence times of infection for kidney patients and a medical data set related to bone marrow transplantation for leukemia.
Impact of a liquid mass on a perfectly plastic solid

The use of steady, normal and oblique shock configurations is explored in calculating the pressure and deformation produced by the impact of a liquid mass on a plane solid surface. Since pressures generated are very large, the change in bulk modulus of the liquid (water) is accounted for by using an equation of state following Field, Lesser & Davies (1979). The impact of a plane-ended liquid mass is analysed using a normal shock for the cases of a rigid surface and a perfectly plastic surface. For the former, it is found that pressures somewhat in excess of the ‘water-hammer’ pressure of linear acoustic theory are predicted, and for the latter there is a critical impact velocity below which no deformation occurs. Above this velocity the surface deforms at a constant rate, producing a pit with maximum depth at the centre. If the liquid mass is wedge-shaped then an oblique shock is formed, which is attached to the contact point provided that the impact Mach number is large enough, as originally shown by Heymann (1969). Pressure and deformation velocity can again be calculated for the cases of rigid and perfectly plastic surfaces respectively. For a rigid surface it is confirmed that pressures considerably in excess of the plane-ended case are produced at shock detachment. For the plastic surface, it is found that there is no critical impact velocity and deformation can occur at any velocity as shock detachment is approached. For a cylindrical liquid mass with a conical tip, the pit produced again has maximum depth at the centre, but with a considerably increased value. The possible use of these models for pitting caused by microjets associated with cavitation bubbles and by impact of liquid drops is discussed.
BOOK REVIEW: Structural Equation Modeling: A Second Course

Structural Equation Modeling: A Second Course, edited by Hancock and Mueller, is an important resource for methodologists, applied researchers, and students of structural equation modeling (SEM) alike. This well-written edited volume provides coverage of a number of important issues and techniques not commonly treated in a didactic manner and specifically not covered in most introductory SEM textbooks. Indeed, the topics covered in this volume are topics for which instructors of SEM courses commonly refer students to supplemental journal article readings (Stapleton & Leite, 2005). This book is particularly valuable in that readers are provided with relevant literature reviews and as such do not have to wrestle with integrating concepts across journal articles with different notation. It is useful in its provision of concrete examples of how to implement each data analytic strategy using common SEM software. In cases where the procedure is not implemented in widely distributed software, chapter authors make clear reference to alternative software and available macros. Hancock and Mueller are to be credited for working carefully with the chapter authors for consistent use of software for their examples, notation, and tone. As such, this volume is much more than a course pack. The following provides a review of the content of each chapter in this edited volume.
Effects of Correlated Colour Temperature and Timing of Light Exposure on Daytime Alertness in Lecture Environments

There is previous evidence that using high correlated colour temperature (Tcp), white light can improve concentration and alertness, resulting in better productivity in office environments. In this study, it was investigated whether the same applies to students exposed to light, while attending lectures. The study consisted of two sequential field studies, conducted during spring and autumn. The subjects were exposed to light provided either by 4,000 K or 17,000 K T5 fluorescent lamps for 90 minute lecture periods. The subjects were asked to judge their level of alertness on a 9-step scale at the beginning, and then at the end of each period. In spring, no change in alertness during the lecture period was detected. There was neither shown correlation between the Tcp of light and subjective alertness. Instead, the study in autumn found that the decrease in alertness during lectures was significant, and post-lunch dip effect appeared strong in the afternoon. The autumn study indicated that exposure of the subjects to a 17,000 K light source in afternoon lectures, potentially assists students to maintain higher levels of alertness, as compared with the results of the 4,000 K light. This study therefore suggests that the colour temperature, and the timing of the light exposure, play important roles in student alertness in lecture room environments.
On the giant, horizontal and asymptotic branches of Galactic globular clusters – V. CCD photometry of NGC 1261

BV CCD photometry is presented for 3352 stars (18 variables) in the globular cluster NGC 1261. The main conclusions drawn from the structure of the colour-magnitude diagram (CMD) are as follows. (i) The location and structure of the main branches agree with those found in previous studies, confirming the existence of a well-defined blue horizontal branch (ii) tail in addition to the large number of red HB stars. (iii) The mean metallicity derived from CMD indicators calibrated with the Zinn & West scale is [Fe/H]=−1.4±0.2, and the very small intrinsic width of the various branches yields very low upper limits (Δ[Fe/H]≤0.06, Δ[CNO]≤0.2) for any chemical abundance spread. (iii) The RGB bump is detected at V=16.70±0.05 as a clump of stars in the luminosity function of the red giant branch
Two-frequency intensity cross-spectrum

The intensity cross-spectrum (spatial Fourier transform of the two-frequency intensity correlation) for scintillations caused by a plane wave passing through a random phase screen is considered. Two series solutions (one valid for low and the other for high spatial frequencies) are obtained which are the generalizations of previous results for the monochromatic intensity spectrum. We show that the Gaussian-field approximation (modeling the cross-spectrum as the transform of the square of the second moment) breaks down when the outer scale is large compared with the diameter of the scattering disk.
The Use of Model Output Statistics (MOS) in Objective Weather Forecasting

Abstract Model Output Statistics (MOS) is an objective weather forecasting technique which consists of determining a statistical relationship between a predictand and variables forecast by a numerical model at some projection time(s). It is, in effect, the determination of the “weather related” statistics of a numerical model. This technique, together with screening regression, has been applied to the prediction of surface wind, probability of precipitation, maximum temperature, cloud amount, and conditional probability of frozen precipitation. Predictors used include surface observations at initial time and predictions from the Subsynoptic Advection Model (SAM) and the Primitive Equation model used operationally by the National Weather Service. Verification scores have been computed, and, where possible, compared to scores for forecasts from other objective techniques and for the official forecasts. MOS forecasts of surface wind, probability of precipitation, and conditional probability of frozen precipi.
On the behaviour of the probability function for selecting the best normal population

SUMMARY When selecting the best normal population with the largest mean, how does the probability function of correct selection behave when the number of observations from a given population increases? In this note we provide answers to this question under a more general setting. A negative and a positive result are given; their proofs involve an application of Slepian's inequality.
Comparative Study of Plastics as Propellants for Laser Ablation Plasma Thrusters

NEW analysis and comparison of laser ablation propulsion(LAP) parameters like speciﬁc impulse and coupling coef-ﬁcientobtainedwhileablatingdifferentprospectiveplasticmaterialsis presented inview ofselecting themost suitable ofthem. Thetestsinvolved a medium–low energy pulsed laser along with a free-moving ballistic pendulum with a target pasted on it. In a novelapplication of 2-D position-sensitive detectors (PSDs) in LAP, thedisplacement measurements were taken by the noncontact opticaltriangulationwithalaser.Theirusegavetheadvantagesofdetectingany unwanted lateral movement of the pendulum. The study shouldhave high utilization for the future LAP applications.Laser ablation propulsion technique, introduced by ArthurKantrowitzin1972,dependsuponthecharacteristicsoflasersourceaswellasthoseofthetargetmaterial,asthemomentumofthetargetis produced in reaction to the generated momentum of the ejectingparticles [1–3]. Speciﬁc impulse values up to several thousandseconds are possible by properly choosing the propellant, that is,targetmaterialandthelaserpulsecharacteristics.Themomentumofthe object may well also depend on the coupling coefﬁcient ofmaterial–laser interaction. Earlier worksinclude ablation with someof the materials included in this study, but here a list of threecommonly available plastics is analyzed and compared [3–6]. Additionally, most researchers have employed mechanical forcesensingforthrustmeasurementorcharge-coupleddeviceimagerfordisplacement measurement [5], whereas others have used electro-magneticcoilsforsensingtorqueonthesuspendedtarget[3]. Ontheother hand, here a noncontact optical triangulation method is beingemployed using a precision PSD with 1 m resolution and a stableHe-Ne laser. This yields direct measurement and better accuracyalongwithlateral-shifterrorreduction,andthususefuloutputcurveshave been obtained.
Active Control of Thermal Buckling of Shells of Revolution Using Piezoelectric Patches

In this paper, the thermal buckling of piezoelectric composite shells of revolution under uniform and linear thermal distributions and selected boundary conditions is investigated by using the semi-analytical finite element. The effects of different parameters such as the type of temperature distributions through the thickness, fiber angles, arrangements of piezoelectric patches and amount of displacement feedback control gain are examined. The results obtained from the present analysis are validated, where possible, with those available in the literature.
Description and analysis of low-frequency fluctuations in vertical-cavity surface-emitting lasers with isotropic optical feedback by a distant reflector

We analyze theoretically and experimentally the polarization dynamics of vertical-cavity surface-emitting lasers exposed to isotropic optical feedback. The theoretical investigations are based on a model that takes into account different inversion populations for charge carriers with opposite spin. In the deterministic case, we observe toruslike synchronized low-frequency fluctuations of one or both polarization modes in the vicinity of the solitary laser threshold, depending on the parameters and initial conditions. Both in experiment and in simulations including spontaneous emission noise, asymmetric low-frequency fluctuations are observed above and below the solitary laser threshold as well as a transition to coherence collapse further above threshold. The amount of excitation of polarization degrees of freedom and thus the occurrence of simultaneous low-frequency fluctuations of both polarization modes is shown to depend on the magnitude of the dichroism. Apart from the correlation properties on the external-cavity time scale, we find a good qualitative agreement between experiments and simulations.
ACLV driven double-patterning decomposition with extensively added printing assist features (PrAFs)

Double exposure lithography processes can offer a significant yield enhancement for challenging circuit designs. Many decomposition techniques (i.e. the process of dividing the layout design into first and second exposures) are possible, but the focus of this paper is on the use of a secondary "cut" mask to trim away extraneous features left from the first exposure. This approach has the advantage that each exposure only needs to support a subset of critical features (e.g. dense lines with the first exposure, isolated spaces with the second one). The extraneous features ("printing assist features" or PrAFs) are designed to support the process window of critical features much like the role of the sub-resolution assist features (SRAFs) in conventional processes. However, the printing nature of PrAFs leads to many more design options, and hence a greater process exploration space, than are available for SRAFs. A decomposition scheme using PrAFs was developed for a gate level process. A critical driver of the work was to deliver improved across-chip linewidth variation (ACLV) performance versus an optimized single-exposure process. A variety of PrAF techniques were investigated, including block type features, variable-pitch PrAFs, and constant assist-to-feature spacing (similar to SRAF placement). A PrAF scheme similar to standard SRAF rules was chosen as the optimal solution. The resulting ACLV benefits occurred mainly in the intermediate pitch range. For dense pitches, the ACLV was mostly unchanged, since in that regime neither process used assist features. The PrAF process showed a benefit of 10-44% improvement of ACLV in the mid-range pitches, but up to 18% worse ACLV for isolated pitches. Thus, the optimal double exposure solution was a combination of SRAFs and PrAFs that achieved the ACLV benefits of both.