Miracle-dz/UniFAR-FTUs huggingface dataset:
Study of a fiber optic sensor for hydrogen leak detection

We present a study of a fiber optic sensor for leak detection based on Surface Plasmon Resonance (SPR). We use Palladium as the sensitive material for hydrogen detection. In this configuration, the transducer layer is a multilayer stack made of a silver, a silica and Pd layer. The spectral modulation of the light transmitted by the fiber allows to detect hydrogen on the environment. The multilayer thickness defines the sensor performance. The silica thickness tunes the resonant wavelength whereas the silver and Pd thickness determines the sensor sensitivity. The study of the sensor performance as function of several thicknesses (Pd/Si/Ag) is achieved and we present the optimal configuration at a concentration of 4% hydrogen in argon.
A marker‐and‐cell approach to free surface 2‐D multiphase flows

This work describes a methodology to simulate free surface incompressible multiphase flows. This novel methodology allows the simulation of multiphase flows with an arbitrary number of phases, each of them having different densities and viscosities. Surface and interfacial tension effects are also included. The numerical technique is based on the GENSMAC front‐tracking method. The velocity field is computed using a finite‐difference discretization of a modification of the Navier–Stokes equations. These equations together with the continuity equation are solved for the two‐dimensional multiphase flows, with different densities and viscosities in the different phases. The governing equations are solved on a regular Eulerian grid, and a Lagrangian mesh is employed to track free surfaces and interfaces. The method is validated by comparing numerical with analytic results for a number of simple problems; it was also employed to simulate complex problems for which no analytic solutions are available. The method presented in this paper has been shown to be robust and computationally efficient. Copyright © 2012 John Wiley & Sons, Ltd.
Calculations of cross‐polar discrimination spread for 20 GHz fixed satellite systems using rain microstructure information

Individual drop images in natural rain from a two‐dimensional video disdrometer (2DVD) have been processed to obtain their shapes, sizes, and orientation angles, which, in turn, have been used to derive their complex forward scattering amplitudes at 19.701 GHz. Using these calculations, the specific attenuation for horizontal and vertical polarizations and the specific differential attenuation and the specific differential phase of all drops over 1 min are determined. A point‐to‐path scaling is used to derive the total rain attenuation for both polarizations as well as the total differential attenuation and the total differential phase. A 19.701 GHz experimental Earth‐space link is simulated to determine the variation of cross‐polar discrimination versus copolar attenuation (XPD‐CPA) and the calculations are compared with 2 years of joint probability XPD‐CPA beacon measurements. The comparisons indicate clearly that the variations in drop shape and drop orientation can give rise to significant spread in XPD.
Design and Development of In Vivo Robot for Biopsy

In vivo robot is an emerging medical technology that could greatly help biopsy and surgery. This paper proposes to design and develop a miniature in vivo robot for biopsy as an add-on to the current endoscope. To allow more dexterity and flexibility, a four degree of freedom (DOF) robot manipulator is proposed. Accordingly, a wire actuated robot with articulated links like in a snake robot has been conceptualized. The robot was mathematically modeled and designed. To test the design, a 4-scaled aluminum model was manufactured. The kinematics of the model is verified experimentally. The four degree of freedom of the miniature robot are: a linear motion of the flexible shaft (first DOF); an axial rotation of the flexible shaft (second DOF); planar through differential wire movement (third DOF); and a combined wire motion for clipper action to take biopsy (fourth DOF). The proposed robot manipulator was modeled in SolidWorks and the kinematic and dynamic analysis was performed using the Robotics Toolbox in MATLAB.
Intermittent turbulence in a pulsating pipe flow

Numerical simulations of the pulsating flow in a pipe of circular cross-section characterized by small imperfections are carried out to determine the conditions leading to the appearance of turbulence. The results show that in the oscillatory case (no steady velocity component of the basic flow), the critical value of the Reynolds number Rδ depends on the Womersley parameter α and, in particular, Rδ increases as α decreases. The critical value of Rδ of the plane wall case is recovered when α is larger than about 10. For moderate values of the Reynolds numbers but larger than the critical one, turbulence appears around flow reversal and breaks the symmetry of the flow, originating a steady velocity component. Moreover, turbulence is not present throughout the whole cycle and there are phases during which the flow relaminarizes. The presence of a steady pressure gradient tends to destabilize the flow and this destabilizing effect becomes larger as the steady velocity component is increased. When turbulence is present, its dynamics is similar to that of the steady case and a log-law layer can be identified both in the oscillatory and the pulsating case.
Weighted Composite Quantile Regression Estimation of DTARCH Models

In modelling volatility in financial time series, the double‐threshold autoregressive conditional heteroscedastic (DTARCH) model has been demonstrated as a useful variant of the autoregressive conditional heteroscedastic (ARCH) models. In this paper, we propose a weighted composite quantile regression method for simultaneously estimating the autoregressive parameters and the ARCH parameters in the DTARCH model. This method involves a sequence of weights and takes a data‐driven weighting scheme to maximize the asymptotic efficiency of the estimators. Under regularity conditions, we establish asymptotic distributions of the proposed estimators for a variety of heavy‐ or light‐tailed error distributions. Simulations are conducted to compare the performance of different estimators, and the proposed approach is used to analyse the daily S&P 500 Composite index, both of which endorse our theoretical results.
Imager‐assisted cloud detection for assimilation of Infrared Atmospheric Sounding Interferometer radiances

The operational assimilation of Infrared Atmospheric Sounding Interferometer (IASI) radiances at the European Centre for Medium‐range Weather Forecasts (ECMWF) relies primarily on the use of clear data, either in completely cloud‐free locations or restricting the assimilation to channels that are insensitive to underlying cloud. Prior to the data assimilation, cloud‐contaminated channels are identified and rejected in cloud detection, i.e. in a screening process based on observation minus background departure data. Background errors have the potential to confuse the cloud detection. On the one hand, a false alarm occurs when a background error is incorrectly interpreted as a cloud. On the other hand, cloud is missed if the background error compensates for the cloud radiative effect.
Dynamic modeling of cusp ion structures

[1] Dispersed ion structures observed near the magnetosphere cusps have long been used to infer locations and properties of reconnection at the Earth's magnetopause. However, observations are often difficult to interpret since spacecraft move relative to a cusp ion structure, creating temporal and spatial ambiguity in the observations. Models of cusp ion structures are also limited to the cases during stable solar wind and interplanetary magnetic field (IMF) because empirical models are used to obtain the Earth's electromagnetic fields. We introduce a new model of a cusp ion structure by using the Liouville theorem particle tracer (LTPT) with the OpenGGCM 3D global MHD model. The OpenGGCM produces time-dependent magnetospheric electromagnetic fields under various solar wind and IMF conditions, while the LTPT traces test particles backward from an observation point to the magnetosheath to map the phase space density and construct an energy-time spectrogram. This allows our model to study cusp ion structures under dynamic solar wind and IMF conditions. In this paper, we first test our model's capability by reconstructing the cusp ion structures observed from three cusp-crossing events of Cluster and Polar satellites. We show that the model reproduces various observed ion structures, such as normal dispersion, reverse dispersion, double dispersions, and stepped dispersion. We then show that the cusp structures observed by Cluster on 23 September 2004 and on 23 August 2003 are temporal structures caused by a sudden increase of solar wind dynamic pressure and various reconnection rates, respectively. We also show that the stepped dispersion observed by Polar on 25 August 1998 is not only spatial but also temporal, caused by two different subsolar reconnection sites during a change of the IMF clock angle. In addition, we find that the ions entering the cusp often cross the magnetopause far away from the reconnection site, even though the reconnection is the cause of precipitation, and that the magnetic configuration of the magnetosheath is also sometimes a cause of energy dispersion in a cusp structure.
A mechanism for moistening the lower stratosphere involving the Asian summer monsoon

This study employs European Centre for Medium‐Range Weather Forecasts (ECMWF) re‐analysis data and the contour advection technique to investigate the water vapour distribution in the upper troposphere and lower stratosphere. Water vapour is the primary greenhouse gas and understanding the processes which determine its distribution and transport is crucial. Of special interest is the exchange of water vapour across the tropopause. This study considers how the Asian summer monsoon affects the moisture budget of the upper troposphere and lower stratosphere. The region of the Asian summer monsoon is identified as a significant moisture source for the upper troposphere outside the deep tropics. Monsoon convection moistens the region of the upper‐level monsoon anticyclone which is located close to the dynamical tropopause, where isentropes cross from the troposphere into the stratosphere. An isentropic analysis reveals that transport from the troposphere into the stratosphere in this region is normally prevented by the strong potential‐vorticity gradients around the tropopause. However, midlatitude synoptic disturbances occasionally interact with the monsoon anticyclone and pull filaments of tropospheric air from its northern flank. These filaments, characterized by high values of humidity and low values of potential vorticity, can extend far north and transport moisture irreversibly into the northern hemisphere lower stratosphere. MOZAIC (Measurement of OZone by Airbus In‐service airCraft) data are used as an independent data source to validate the results obtained from the ECMWF analyses.
Kilometer scale kinetic energy perturbations in the mesosphere derived from EISCAT velocity data

Traditionally, radar instruments which obtain coherent echoes from structures delineated by sharp gradients in refractive index have been used as a means of determining parameters describing neutral turbulence in the middle atmosphere. In these cases the very characteristics of the coherent signals are used. An alternative, somewhat akin to using velocity estimations from meteor trails and trails of artificially introduced racers, is to determine the kinetic energy perturbation from the velocity profiles alone, the latter being available from incoherent scatter radar. Here we describe a method which assumes that the velocity fluctuations are caused by perturbations of a 1‐km scale, in the buoyancy subrange, but which still may be indicative of energy flux at the outer scale, illustrated by the remarkable similarity to energy dissipation rates determined by other measurements.
Minimax hypothesis testing about the density support

The paper is concerned with testing nonparametric hypotheses about the underlying support G of independent and identically distributed observations. It is assumed that G belongs to a class . Cf' of compact sets with smooth upper surface called boundary fragments. It is required to distinguish the simple null hypothesis specified by a known set Go in ~ against nonparametric alternatives that G belongs to a class obtained by removing a certain neighbourhood of Go in ~. Using the asymptotic minimax approach, the problem is to determine the order of the smallest distance between the null hypothesis Ho and the alternatives for which one is able to test the null hypothesis against the alternatives with a given summarized error.
PREPARING WRITING TEACHERS TO USE ASSESSMENT RUBRICS

This article presents a qualitative study that was derived from a course on teaching L2 writing at a U.S. institution and analysis of participants’ experience designing and utilizing assessment rubrics. Primarily relying on narrative accounts, it aimed to demonstrate how an explicit approach to teaching issues in assessment, particularly the use of rubrics to assess student writing, can be incorporated into pedagogy courses on teaching writing. Data sources included participants’ rubrics developed for various L2 writing contexts, including first-year composition, EFL reading-writing courses, and U.S. schools teaching Grades K –4. Participants’ written reflections on rubric design and interviews about their rubric implementations were also examined. Results showed that explicit teaching about the use of rubrics as assessment tools could prepare writing teachers to use rubrics more effectively. The article concludes with recommendations for improving and reevaluating how the use of rubrics as writing assessment tools can be integrated into teacher education and teacher training programs so that teachers are better prepared in this area of instruction.
Laser Doppler velocimetry using a bulk optic Michelson interferometer: A student laboratory experiment

The Doppler frequency of reflected light from a moving mirror is measured using a Michelson interferometer and a low cost spectrum analyzer. The experimental data for the Doppler frequency are in agreement with the calculated theoretical values with a standard percent error of 0.54%. The concept of optical mixing of a phase‐modulated signal with the Doppler signal is presented, with a derivation of the resulting detected signal power, using the small phase modulation amplitude approximation. An experiment is described using laser Doppler velocimetry to heterodyne the Doppler signal with an acoustic wave. The experiment provides a good illustration of the Doppler effect, spectral analysis, and principles of optical mixing and interferometry in an advanced undergraduate laboratory.
The Bipolar Outflow toward G5.89–0.39

We present high-resolution observations of G5.89-0.39 in CO(1 → 0), 13CO(1 → 0), C18O(1 → 0), and HCO+(1 → 0). We characterize the G5.89-0.39 outflow using the 13CO emission. The outflow is found to be young, massive, and powerful. We conclude that (1) the outflow is nearly along the line of sight, (2) there is dynamical evidence for entrainment of ambient interstellar material into the outflow, (3) the mass entrainment rate is ~4 × 10-3 M☉ yr-1, (4) in the blue lobe, only ~27% of the outflow mass is due to entrainment, and (5) expansion of the outflow lobes perpendicular to the flow axis is occurring at ~1-10 vsound. A neutral and ionized outflow tracer are compared. Watson and coworkers predicted that if entrainment through the Kelvin-Helmholtz shear instability adds significantly to the outflow mass, a difference in the turbulent velocity widths of neutral and ionized outflow tracers could be measurable. We cannot conclude that the Kelvin-Helmholtz shear instability is the physical process causing this entrainment, but it may operate at a level below our detection limit.
R-matrix calculations for electron impact excitation of Fe II: LS coupling and Breit-Pauli approximations

Two sets of close coupling calculations have been carried out on the Cray-2 and the Cray Y-MP using the R-matrix method: (i) a 38-term calculation in LS coupling and (ii) a 41-level fine structure calculation in the Breit-Pauli approximation. The first set includes the quartet and sextet terms dominated by the configurations 3d64s, 3d7 and 3d64p and collision strengths are calculated for all 703 transitions in LS coupling. The second set of calculations is carried out using the Breit-Pauli version of the R-matrix method and includes a number of the important fine structure levels from the quartet and the sextet multiplets and 820 corresponding transitions. Detailed autoionization structures are obtained in both sets of collision strengths, and a significant enhancement is seen in the effective collision strengths for a number of transitions due to the resonances: for example, an enhancement of factors of 1.4, 2.5 and 1.15 respectively for transitions from the 6D ground term to the lowest 4F, 4D and 4P terms.
Spectral line profiles of iron and nickel in supernova 1987A. Evidence for a fragmented nickel bubble

Les profils des raies des elements du groupe du fer observees dans les spectres IR de la supernova 1987A sont presentes. On suggere que les elements du groupe du fer possedent une distribution spatiale unique dans la matiere ejectee, et que les profils sont dus a l'emission emanant d'une region interieure a basse densite (la bulle de nickel) qui s'est fragmentee en balles a grandes vitesses.
THE MAXIMUM POWER OUTPUT AND MAXIMUM EFFICIENCY OF AN IRREVERSIBLE CARNOT HEAT ENGINE

The effect of thermal resistance, heat leakage and internal irreversibility resulting from the working fluid on the performance of a Carnot heat engine is investigated using a new cyclic model. The power output and efficiency of the heat engine are adopted as objective functions for heat engine optimization. The optimal performance of the heat engine is analysed systematically. Some significant results are obtained. For example, the maximum power output and maximum efficiency are determined. The efficiency of the heat engine at maximum power output and the power output of the heat engine at maximum efficiency are also calculated. Curves of the power output varying with the efficiency of the heat engine are obtained. These curves can indicate clearly the rational regions of efficiency and power output for an irreversible Carnot heat engine. It is pointed out that all the conclusions concerning a reversible Carnot heat engine, an endoreversible Carnot heat engine only affected by thermal resistance and an irreversible Carnot heat engine with internal irreversibility and/or heat leakage can be deduced from the results in this paper.
Evaluation of Regional Climate Simulations of the 1998 and 1999 East Asian Summer Monsoon using the GAME/HUBEX Observational Data

A regional climate model based on the Penn State/NCAR Mesoscale Model (MM5) was used to simu-late the 1998 and 1999 East Asian summer monsoon conditions. Simulations were performed for 1 April–31 August of each year, with initial and lateral boundary conditions provided by the ECMWF analysis. Observations from the 1998 and 1999 GAME/HUBEX experiments were used to evaluate the regional climate simulations. Based on observations, large differences can be found between the 1998 and 1999 meteorological conditions and surface energy budgets at the Shouxian station during the IOPs, with much higher rain intensity but only slightly higher rain frequency in 1998 than 1999. For 1998, although the regional climate model was able to reproduce the general spatial distribution of monthly mean rainfall quite well during the summer monsoon season, large discrepancies can be found in comparing the observed and simulated surface climate and energy ﬂuxes in the HUBEX region. By using Four Dimensional Data Assimilation (FDDA) technique, which constrains the simulated large-scale circulation with observations from 21 soundings in the HUBEX a -scale region, both the root mean square error and mean bias in rainfall were greatly reduced. The improvements in simulating rainfall were related to both reduction in errors of precipitation amount and timing. In the control simulation, a mean bias of (cid:1) 63 W/m 2 ( (cid:1) 36%) was found in the simulated surface net radiation at Shouxian, which suggest large errors in simulating clouds in the region. With FDDA, the bias was signiﬁcantly reduced to (cid:1) 23 W/m 2 ( (cid:1) 13%), with corresponding reduction of bias in the latent heat ﬂux. This suggests that at least part of the model bias in simulating net radiation is related to errors in simulating the large-scale circulation, which can affect cloud amount and vertical distribution. Comparing the 1998 and 1999 simulations, both without FDDA, smaller biases were found in the surface ﬂuxes during 1999. Percentage biases in the net radiation and latent heat ﬂux were (cid:1) 18% and (cid:1) 33% in 1999 and (cid:1) 36% and (cid:1) 50% in 1998 respectively. Based on observations, large differences in the net surface radiation, and small differences in cloud fraction between the two years suggest that cloud optical depth and/or vertical distribution were very different, with more cloudy conditions observed during 1999. Although the 1999 simulations were sensitive to the cumulus convective parameterizations (Grell scheme versus Kain-Fritsch scheme) as shown by the sensitivity experiments, the large differences in simulation skill between the 1998 and 1999 cases, regardless of the convection schemes used, suggest possible dependence of model errors on cloud properties that deserve further investigations.
On Asymptotic Distributions and Confidence Intervals for LIFT Measures in Data Mining

A LIFT measure, such as the response rate, lift, or the percentage of captured response, is a fundamental measure of effectiveness for a scoring rule obtained from data mining, which is estimated from a set of validation data. In this article, we study how to construct confidence intervals of the LIFT measures. We point out the subtlety of this task and explain how simple binomial confidence intervals can have incorrect coverage probabilities, due to omitting variation from the sample percentile of the scoring rule. We derive the asymptotic distribution using some advanced empirical process theory and the functional delta method in the Appendix. The additional variation is shown to be related to a conditional mean response, which can be estimated by a local averaging of the responses over the scores from the validation data. Alternatively, a subsampling method is shown to provide a valid confidence interval, without needing to estimate the conditional mean response. Numerical experiments are conducted to compare these different methods regarding the coverage probabilities and the lengths of the resulting confidence intervals.
Determination of the functional form of the relationship of covariates to the log hazard ratio in a Cox model

In this paper, we review available methods for determination of the functional form of the relation between a covariate and the log hazard ratio for a Cox model. We pay special attention to the detection of influential observations to the extent that they influence the estimated functional form of the relation between a covariate and the log hazard ratio. Our paper is motivated by a data set from a cohort study of lung cancer and silica exposure, where the nonlinear shape of the estimated log hazard ratio for silica exposure plotted against cumulative exposure and hereafter referred to as the exposure–response curve was greatly affected by whether or not two individuals with the highest exposures were included in the analysis. Formal influence diagnostics did not identify these two individuals but did identify the three highest exposed cases. Removal of these three cases resulted in a biologically plausible exposure–response curve.