Miracle-dz/UniFAR-FTUs huggingface dataset:
Investigation of a co-flowing buoyant jet: experiments on the effect of Reynolds number and Richardson number

Experiments have been carried out on a vertical jet of helium issuing into a co-flow of air at a fixed exit velocity ratio of 2.0. At all the experimental conditions studied, the flow exhibits a strong self-excited periodicity. The natural frequency behaviour of the jet, the underlying flow structure, and the transition to turbulence have been studied over a wide range of flow conditions. The experiments were conducted in a variable-pressure facility which made it possible to vary the Reynolds number and Richardson number independently. A stroboscopic schlieren system was used for flow visualization and single-component laser-Doppler anemometry was used to measure the axial component of velocity. The flow exhibits several interesting features. The presence of co-flow eliminates the random meandering typical of buoyant plumes in a quiescent environment. The periodicity of the helium jet under high-Richardson-number conditions is striking. Under these conditions transition to turbulence consists of a rapid but highly structured and repeatable breakdown and intermingling of jet and free-stream fluid. At Ri = 1.6 the three-dimensional structure of the flow is seen to repeat from cycle to cycle. The point of transition moves closer to the jet exit as either the Reynolds number or the Richardson number increases. The wavelength of the longitudinal instability increases with Richardson number. At low Richardson numbers, the natural frequency scales on an inertial timescale, τ1 = D/Uj where D is the jet diameter and Uj is the mean jet exit velocity. At high Richardson number, the natural frequency scales on a buoyancy timescale, τ2 = [ρjD/g(ρ∞ -ρj)]½ where g is the gravitational acceleration and ρj and ρ∞ are the jet and free-stream densities respectively. The transition from one flow regime to another occurs over a narrow range of Richardson numbers from 0.7 to 1. A buoyancy Strouhal number is used to correlate the high-Richardson-number frequency behaviour.
A Comparison of the Transition of Equatorial Waves between Two Types of ENSO Events in a Multilevel Model

AbstractThe differences in the transitions of equatorial mixed Rossby–gravity (MRG) waves to off-equatorial tropical depression (TD)-type disturbances during ENSO events are investigated with a global baroclinic anomaly model. The model reproduces reasonably the perturbation evolution within realistic three-dimensional summer mean states corresponding to El Nino (EN) and La Nina (LN) years. Based on wave structure and energetics diagnosis, the results indicate that, following the longitudinal shift of the favorable environmental fields, the wave characteristics are altered accordingly. In the presence of a circulation–convection feedback, the wave train exhibits more rapid growth, a more eastern location of transition, and a more northward-shifting component during EN years than during LN years. The convective heating acts as a leading energy source to supply the wave growth and the increase in eddy kinetic energy is directly attributed to barotropic conversion in the monsoon region.Sensitivity experiment.
Electronic transport in single-walled carbon nanotube/graphene junction

Graphene/carbon nanotube (CNT) junctions were fabricated by depositing mechanically exfoliated graphene on substrate followed by direct chemical vapor deposition growth of CNT, and their electronic transport properties were investigated. Unlike metallic CNT/graphene junction with good contact, there exists an obvious Schottky barrier between semiconducting CNT and graphene due to the difference of their work functions, which lead to typical rectification properties and directionally field-effect behavior.
Phase diagram and magnetic structure investigation of the fcc antiferromagnetHoB12

We have investigated the magnetic structure of the fcc antiferromagnet $\mathrm{Ho}{\mathrm{B}}_{12}$ by magnetization and specific heat measurements on small single crystals prepared from natural elements and by neutron diffraction on isotopically enriched powder samples. Magnetization measurements up to $9\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ show up to three magnetic phases in the $B$ vs $T$ phase diagram, depending on the orientation of the applied field. The specific heat in zero field exhibits a very steep increase at ${T}_{N}=7.4\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, but its maximum is reached only at a lower temperature. In applied magnetic field up to $8\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ additional $\ensuremath{\lambda}$-like anomalies are observed which confirm the phase boundaries from the magnetization measurements. Powder neutron diffraction in zero magnetic field reveals an antiferromagnetic structure below ${T}_{N}$. The basic reflections can be indexed with $(1∕2\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta}\phantom{\rule{0.3em}{0ex}}1∕2\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta}\phantom{\rule{0.3em}{0ex}}1∕2\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta})$, where $\ensuremath{\delta}=0.035$, pointing to an incommensurate magnetic structure. In a field below $2\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ (in the lowest-field magnetic phase) the principal reflections remain; in a higher magnetic field they become suppressed. Moreover, the magnetic background strongly decreases with applied field. The analysis of results shows that an amplitude-modulated, incommensurate structure likely represents the magnetic order of $\mathrm{Ho}{\mathrm{B}}_{12}$. The very complex phase diagram of this compound can arise from the interplay between the RKKY and dipole-dipole interaction and/or from frustration effects in the fcc-symmetry lattice.
The realizable resistive limit: A new concept for mapping geological features spanning a broad range of conductances

The integral of the step response from zero time to infinite time (the ideal resistive limit) can be used to determine the conductance of the ground, in theory, because the former is directly proportional to the latter. However, in a real time‐domain airborne electromagnetic (AEM) system, it is impossible to measure the step response, or the ideal resistive limit. This is because (1) the off time is finite, being interrupted by the next transmitter pulse; (2) the total effect of all previous transmitter pulses is to reduce the measured response; and (3) the process of removing the primary field during the on time removes a component of the secondary response that has the same shape as the primary response. With a real time‐domain AEM system, it is possible to estimate what is defined as the realizable resistive limit (RRL). The RRL can also be calculated theoretically for a horizontal thin sheet of known conductance. Hence, the measured data can be input into a nonlinear inversion scheme and used to estim.
Insights into the Origin of the Galaxy Mass-Metallicity Relation

Abstract We examine mass–metallicity relations for nearby (D < 2 Mpc) gas-rich and gas-poor dwarf galaxies. We derived stellar and baryonic masses using photometric data and used average stellar iron abundances as the metallicity indicator. With the inclusion of available data for massive galaxies, we find a continuous mass–metallicity relation for galaxies spanning nine orders of magnitude in mass, and that the mass–metallicity relations are the same for both gas-rich and gas-poor dwarf galaxies. We derive stellar effective yields from the stellar abundances, finding that gas-poor dwarf galaxies form a single sequence with mass, whereas gas-rich dwarf galaxies have higher yields at comparable mass. Simple chemical evolution models show that a mass-dependent star-formation efficiency can simultaneously account for the correlations between metallicity, gas fraction, and stellar effective yield with mass. In agreement with recent and independent results, we conclude that a key driver of the mass-metallicity relation is the variation of star-formation efficiency with galaxy mass, modulated by galaxy mass-dependent outflows and/or stellar IMF variations, and coupled with environmental gas-removal processes.
STEPS TOWARD UNVEILING THE TRUE POPULATION OF ACTIVE GALACTIC NUCLEI: PHOTOMETRIC CHARACTERIZATION OF ACTIVE GALACTIC NUCLEI IN COSMOS

Using a physically motivated, model-based active galactic nucleus (AGN) characterization technique, we fit a large sample of X-ray-selected AGNs with known spectroscopic redshifts from the Cosmic Evolution Survey field. We identify accretion disks in the spectral energy distributions of broad- and narrow-line AGNs, and infer the presence or absence of host galaxy light in the SEDs. Based on infrared and UV excess AGN selection techniques, our method involves fitting a given SED with a model consisting of three components: infrared power-law emission, optical-UV accretion disk emission, and host galaxy emission. Each component can be varied in relative contribution, and a reduced chi-square minimization routine is used to determine the optimum parameters for each object. Using this technique, both broad- and narrow-line AGNs fall within well-defined and plausible bounds on the physical parameters of the model, allowing trends with luminosity and redshift to be determined. In particular, based on our sample of spectroscopically confirmed AGNs, we find that approximately 95% of the broad-line AGNs and 50% of the narrow-line AGNs in our sample show evidence of an accretion disk, with maximum disk temperatures ranging from 1 to 10 eV. Because this fitting technique relies only on photometry, we hope to apply it in future work to the characterization and eventually the selection of fainter AGNs than are accessible in wide-field spectroscopic surveys, and thus probe a population of less luminous and/or higher redshift objects without prior redshift or X-ray data. With the abundant availability of photometric data from large surveys, the ultimate goal is to use this technique to create large samples that will complement and complete AGN catalogs selected by X-ray emission alone.
IMPROVING SIMULATION EFFICIENCY WITH QUASI CONTROL VARIATES

In a simulation one can often identify a random variable, Y, that is likely to be highly correlated with a random variable of interest, X. If μ Y =E(Y) is known then Y can be used as a control variate to estimate μ X =E(X) more efficiently than by a direct simulation of X. We study the asymptotic properties of a method that uses Y to potentially speed up the simulation when μ Y is not known. The method is effective when μ Y can be efficiently estimated in an auxiliary simulation that does not involve X. We call Y a quasi control variate (QCV). For a simulation of length t>0 time units, we invest pt units estimating μ Y with the auxiliary simulation, yielding Y¯ pt . The remaining qt=(1−p)t units are spent on the main simulation yielding estimates (X˜ qt ,Y˜ qt ) for (μ X ,μ Y ). The two simulations can be interleaved so they are effectively done simultaneously. For each p∈(0,1) and α∈R we have a QCV estimator for μ X , We find p and α that minimize the asymptotic variance parameter (AVP) of Xˆ t (p,α) in terms of statistics that are estimated during the simulations, and then describe an easily implemented adaptive procedure that achieves the minimum AVP. The adaptive procedure evolves into the optimal QCV procedure if it is more efficient than a direct simulation, X¯ t →μ X ; otherwise it evolves into the direct simulation. Applications in stochastic linear programming, stochastic partial differential equations (PDE's) and queuing theory are cited.
Diabetic Self-Management Education – Effect on Self-Management Care of Type-2 Diabetic Patients

A common problem of a person with diabetes mellitus was the lack of discipline in implementation of their daily self-care management. Diabetes Self-Management Education (DSME) was a system to help diabetes patients manage their activities to improve their health. DSME is the process which can improve the knowledge, skill, and ability of diabetes self-care. This study aimed to determine the effect of using diabetes self-management education (DSME) intervention and how it affected patients’ self-care management. This research was quasi experiment with one group pretest-posttest among patients with type-2 diabetes. There were 30 participants assigned by using purposive sampling into DSME intervention. Four sessions of DSME were conducted to the participants using illustrative media/fliers. The data were collected by questionnaires of Diabetes Self-Care Management. Then, it was analyzed by using paired t-test. The results showed that self-care management of the respondents before the intervention was 28.8 and it increased to 35.3 after the intervention (mean different=6.5). There were differences in the self-care score before and after the intervention (p=0.001). This study has limited time to do DSME. But, in four sessions, we have tried to explain more about diabetes interactively. Then, better to assess the type-2 diabetes patients with qualitative method or mixed with more participants included for the future researchers. This research was adopting a DSME to found significant improvements in the self-care management in type-2 diabetes mellitus patient. This demonstrates that DSME intervention can be such clinical importance in care of type-2 diabetes mellitus patient.Keywords: Diabetes self-management education, self-care management, type-2 diabetes patients.
On the Criterion for the Determination Transition Onset and Breakdown to Turbulence in Wall-Bounded Flows

Starting from the basic conservation laws of fluid flow, we investigated transition and breakdown to turbulence of a laminar flat plate boundary layer exposed to small, statistically stationary, two-component, three-dimensional disturbances. The derived equations for the statistical properties of the disturbances are closed using the two-point correlation technique and invariant theory. By considering the equilibrium solutions of the modeled equations, the transition criterion is formulated in terms of a Reynolds number based on the intensity and the length scale of the disturbances. The deduced transition criterion determines conditions that guarantee maintenance of the local equilibrium between the production and the viscous dissipation of the disturbances and therefore the laminar flow regime in the flat plate boundary layer
Broad Doublet and Plasmon Peak in Perovskite-Type Oxides

The 180° light scattering experiment has been performed in a Nb-doped SrTi 16 O 3 sample. The spectral intensity of a broad doublet (BD) is found to be very weak, supporting the reported hypothesis that a partially softened transverse acoustic mode is the physical origin of the BD. In addition to the BD of weak intensity, two spectral peaks, which do not exist in pure SrTi 16 O 3 , are found and assigned to “plasmon-LO phonon coupled modes”. The similar behavior between the BD and the coupled modes is discussed.
Surface Roughness Effects on Induced Flow and Frictional Resistance of Enclosed Rotating Disks

Disk friction losses in a pump are caused by the fluid flow in the gap between the impeller and the casing wall. The classical method of determining these losses is by using a thin plain disk rotating in a close fitting close casing. Rotating disks can be classified in two broad categories: (1) Free disk, a disk which rotates in a fluid mass of infinite extent and initially at rest. When the disk is rotating fluid is drawn axially toward the disk and is centrifuged off its periphery as a spinning boundary layer. There is no angular momentum in the approach flow so the friction torque is equal to the angular momentum cast off in the boundary layer. (2) Enclosed disk, a disk which rotates within a chamber of finite dimensions. When the disk is rotating the whirling flow cast off its periphery eventually returns to the disk retaining some of its angular momentum. For this reason the friction torque on enclosed disks is less than that on free disks. This investigation concerns the latter case which includes the kinds of conditions encountered in centrifugal machinery where problems of disk friction torque and power loss are related to the circulationmore » and secondary flows induced by the rotating elements. « less
Convex conservation laws with discontinuous coefficients. existence, uniqueness and asymptotic behavior

Existence and uniqueness is proved, in the class of functions satisfying a wave entropy condition, of weak solutions to a conservation law with a flux function that may depend discontinuously on the space variable. The large time limit is then studied, and explicit formulas for this limit is given in the case where the initial data as well as the x dependency of the flux vary periodically. Throughout the paper, front tracking is used as a method of analysis. A numerical example which illustrates the results and method of proof is also presented.
Age, Depression, and Attrition in the National Survey of Families and Households

It might seem that following people over time provides the best indication of how people change with age. Sample attrition can undermine that assumption. This study describes the impact of health, impairment, and depression on attrition in the National Survey of Families and Households. It analyzes the impact of that attrition on estimates of the age-specific changes in depression over a six-year period. In doing so, it illustrates methods for assessing and perhaps correcting the effects of attrition. Results show that the cross-sectional relationship of baseline depression to age differs sharply for those who later drop out compared with those who stay in. Much of the difference, but not all, vanishes with adjustment for health and impairment. The probability of dropping out increases with poor health, impairment, and depression at baseline. The impact of impairment and depression on attrition increases with age. Panel models that ignore the attrition imply that depression decreases in old age. Models that adjust for the hazard of attrition imply that depression rises by an amount that increases with age.
An artificial neural network model application for the estimation of thermal comfort conditions in mountainous regions, Greece

In this research, an artificial neural network model (ANN) was applied to estimate the thermal comfort conditions in the mountainous regions of Gerania (MG) and of Nafpaktia (MN) in Greece. Air temperature and relative humidity were recorded from June to August 2007 at two selected sites for each study region. Data of the aforementioned parameters were used for the calculation of the thermohygrometric index (THI), from which thermal comfort conditions were evaluated as classes. The ANN model, the multilayer perceptron (MLP) was used for the estimation of THI values at the examined high altitude level (1334 and 1338 m in MG and MN, respectively) based on the temperature and the relative humidity of the examined low altitude level (650 m in MG and 676 m in MN), taking into account the actual time of measurement (ATM). The results of the development and application of this extended MLP model indicated more accurate estimations of THI values at the two study regions during the whole day period compared to the MLP application without the use of ATM. Also, the extended model, examining the whole day, showed more accurate estimations of THI values in MG compared to MN. Similarly, this model provided better estimations separately for both daytime (09h00min-20h00min) and nighttime (21h00min-08h00min) in comparison with the respective THI estimations taking into account only the air temperature and relative humidity as input parameters. Additionally, the extended MLP model was more efficient estimating THI values during daytime hours compared to nighttime hours in both MG and MN. Also, the extended MLP model was more capable in estimating better the THI values in the “hot” class in MG as well as in the “comfortable” class in MN.
Curvature particle pinch in tokamak and stellarator geometry

A study of the curvature pinch effect in various fusion devices (both tokamaks and stellarators) is presented. Canonical density profiles are calculated employing the theory developed by M. B. Isichenko, A. V. Gruzinov, P. H. Diamond, and P. N. Yushmanov [Phys. Plasmas 3, 1916 (1995)]. In tokamaks, it is found that the curvature pinch is relatively strong (especially in a spherical tokamak) and usually leads to a peaked density profile. In stellarators, the curvature pinch is weaker and can have either sign.
Decay of Isotropic Turbulence Generated by a Mechanically Agitated Grid

Experimental study of weak isotropic turbulence, created by a mechanically agitated grid, has indicated that in the absence of large linear‐momentum wakes the energy of turbulence relaxes very quickly into a stable self‐preserving structure, which, depending on the initial Reynolds number of turbulence, decays at different constant inverse powers of time. Both the longitudinal correlation coefficients and the corresponding spectral distributions, except for the difference in the parametric constants, are of the same functional type as those found previously for a passive grid.
Inference about the mean of a skewed population: a comparative study

We consider the problem of hypotheses testing and interval estimation of the mean of a possibly skewed population. The usual procedures based on the large sample distribution of the studentized sample mean can be imprecise because of the violation of the nominal values of test sizes or confidence levels. Many attempts were made to overcome this problem. Most of them are based on correcting the studentized t-variable with higher order terms and possibly using the bootstrap to set critical values. Another approach is based on the empirical likelihood and possibly using the bootstrap or the Bartlett correction to improve the calibration. In this article, using simulation techniques, we investigate and compare these competing approaches in terms of the attainment of the nominal values of test sizes, confidence levels and the powers of the associated tests. It is found that intervals based on the Bartlett-corrected empirical likelihood are very accurate even for small sample sizes from highly skewed populations. Its power performance is also comparable and in many ways better than the other procedures considered, besides its applicability for testing when all other procedures fail to attain the nominal sizes of the tests.
Binary Regression with Stochastic Covariates

In binary regression the risk factor X has been treated in the literature as a non-stochastic variable. In most situations, however, X is stochastic. We present solutions applicable to such situations. We show that our solutions are more precise than those obtained by treating X as non-stochastic when, in fact, it is stochastic.
The structure of the intertropical front over N.W. India during the S.W. Monsoon

This paper investigates the structure of the intertropical front over N.W. India by means of the daily radio-sonde and meteorological flight observations made during ten days of undisturbed weather during the monsoon of 1945. The conclusions are incorporated in the schematic cross sections (Figs. 12 and 13). In the course of the investigation it is found that the winds in the continental air are notably sub-geostrophic. No explanation of this is given.
Theory of traffic jam in a one-lane model

We propose a generalized optimal velocity model to describe one-lane traffic flows. We carry out a weakly nonlinear analysis based on the technique of soliton perturbations and determine the selected propagating velocity, amplitude, and width of the interface between a jam state and a nonjam state. From the direct simulation of the model, we have confirmed the validity of our theoretical analysis.