Miracle-dz/UniFAR-FTUs huggingface dataset:
Experimental and Numerical Investigation of Impingement Cooling in a Combustor Liner Heat Shield

A combined experimental and numerical investigation of the heat transfer characteristics inside an impingement cooled combustor liner heat shield has been conducted. Due to the complexity and irregularity of heat shield configurations, standard correlations for regular impingement fields are insufficient and detailed investigations of local heat transfer enhancement are required. The experiments were carried out in a perspex model of the heat shield using a transient liquid crystal method. Scaling of the model allowed to achieve jet Reynolds numbers of up to Re j = 34, 000 without compressibility effects. The local air temperature was measured at several positions within the model to account for an exact evaluation of the heat transfer coefficient. Analysis focused on the local heat transfer distribution along the heat shield target plate, side rims, and central bolt recess. The results were compared with values predicted by a standard correlation for a regular impingement array. The comparison exhibited large differences. While local values were up to three times larger than the reference value, the average heat transfer coefficient was approximately 25% lower. This emphasized that standard correlations are not suitable for the design of complex impingement cooling pattern. For thermal optimization the detailed knowledge of the local variation of the heat transfer coefficient is essential. From the present configuration, some concepts for possible optimization were derived. Complementary numerical simulations were carried out using the commercial computational fluid dynamics (CFD) code ANSYS CFX. The motivation was to evaluate whether CFD can be used as an engineering design tool in the optimization of the heat shield configuration. For this, a validation of the numerical results was required, which for the present configuration was achieved by determining the degree of accuracy to which the measured heat transfer rates could be computed. The predictions showed good agreement with the experimental results, both for the local Nusselt number distributions as well as for averaged values. Some overprediction occurred in the stagnation regions, however, the impact on overall heat transfer coefficients was low and average deviations between numerics and experiments were in the order of only 5-20%. The numerical investigation showed that contemporary CFD codes can be used as suitable means in the thermal design process.
A Generalized Method for Estimating the Structure of the Equatorial Atlantic Cold Tongue: Application to Drifter Observations

A generalized method is developed to determine the position of the Atlantic northern cold tongue front across its zonal extent from satellite sea surface temperature (SST) data. Previous approaches estimated the frontal position subjectively or individually, calling for a more objective technique that is suitable for large datasets. The developed methodology is based on a median frontal SST, and associated positional uncertainties are on the order of 0.38 latitude for the period 1998‐2011. Frontal characteristics are generally consistent with tropical instability waves (TIWs) and interannual variations are large. Application to drifter observations shows how the new methodology can be used to better understand circulation features near the northern cold tongue front. A drifter pair deployed on the eastern side of a passing TIW crest north of the frontrevealedthatthetrajectoriesofthedrifterswereclearlyinfluencedbytheshapeofthefrontandtheydid not cross the front, but rather stayed close together about 2.58 north of the front. In a more complete analysis using all available drifters near the Atlantic northern cold tongue front, only about 12% of the trajectories crossed the front. Analyses in an along- and cross-frontal frame of reference complement isopycnal coordinate mapping, and tropical Atlantic drifter velocities averaged in frontal coordinates indicate a broadened shear zone between the northern branch of the South Equatorial Current and North Equatorial Countercurrent as well as meridional convergence near the front.
Relatively Monotone and Relatively Generalized Monotone Maps in Nonsmooth Setting and Relative r-Monotonicity

Abstract The aim of this article is twofold. First, we consider relatively monotone, relatively pseudomonotone, and relatively quasimonotone maps in nonsmooth setting. For continuous maps, we describe -monotonicity when the relative parameters are different and prove that -quasimonotonicity implies -quasimonotonicity as well as -pseudomonotonicity implies -pseudomonotonicity. Then, under local Lipschitzianity assumption, we establish first-order criteria for -monotonicity, -pseudomonotonicity, and -quasimonotonicity. Second, we introduce and study the new notion of relatively r-monotone operators. We provide characterizations and properties. We give in particular criteria of first order for relative r-monotonicity, in smooth and nonsmooth locally Lipschitz settings, when the relative parameters are equal.
Role of achievement value, teachers’ autonomy support, and teachers’ academic pressure in promoting academic engagement among high school seniors

This study investigated the effects of individual and contextual factors (students and classrooms) on academic engagement by adopting an analytical approach based on hierarchical linear modeling. The participants in this study included 906 high school students (42.7% male) from 42 classrooms in South Korea. We established that achievement value and teachers’ autonomy support had a statistically significant positive impact on academic engagement at both the student and classroom levels. However, teachers’ academic pressure had a positive impact on academic engagement only at the classroom level. Cross-level interaction effects between the student and classroom levels, achievement value (LV 1) and autonomy support (LV 2), teachers’ academic pressure (LV1) and achievement value (LV 2), and those on teachers’ academic pressure at both levels were also identified.
A Risky Business?: Ukrainian Migrant Women in Warsaw's Domestic Work Sector

A Risky Business? geeft een gedetailleerde analyse van de besluitvormingsprocessen van vrouwelijke oekraiense migranten die naar Polen emigreren om daar als huishoudelijke hulp te gaan werken. Deze studie laat zien hoe de sociale banden en migrantenorganisaties de machtsongelijkheid tussen een migrant, de staat en een werkgever effectief verkleinen. A Risky Business? belicht de complexheid aan risico's enerwaar arbeidsmigranten mee te maken hebben en hun behendige reactie daarop.
The role of oil price in determining the relationship between cryptocurrencies and non-fungible assets

ABSTRACT This study aimed to explain the relationship between bitcoin and nonfungible tokens (NFTs) to determine if the NFT is an alternative investment to bitcoin or a complement during oil price uncertainty. The results showed a comovement between NFT and bitcoin prices. However, after excluding the effect of oil prices and using the partial wavelet coherence test, the results changed and the comovements disappeared: bitcoin and NFT became two separate assets that are affected by different variables. Moreover, oil price has more impact on bitcoin than NFT in the medium and long run. However, these results indicate that the change in oil prices, to some extent, is not considered a strong influence on the crypto market. Nevertheless, a significant rise in crude oil prices leads to a significant change in the comovement between crypto assets and they become interrelated.
Diagnostic based modeling for determining absolute atomic oxygen densities in atmospheric pressure helium-oxygen plasmas

Absolute atomic oxygen ground state densities in a radio-frequency driven atmospheric pressure plasma jet, operated in a helium-oxygen mixture, are determined using diagnostic based modeling. One-dimensional numerical simulations of the electron dynamics are combined with time integrated optical emission spectroscopy. The population dynamics of the upper O 3p P3 (λ=844 nm) atomic oxygen state is governed by direct electron impact excitation, dissociative excitation, radiation losses, and collisional induced quenching. Absolute values for atomic oxygen densities are obtained through comparison with the upper Ar 2p1 (λ=750.4 nm) state. Results for spatial profiles and power variations are presented and show excellent quantitative agreement with independent two-photon laser-induced fluorescence measurements.
Quasi-Biweekly Mode and Its Modulation on the Diurnal Rainfall in Taiwan Forecasted by the CFS

AbstractThe occurrence of diurnal afternoon convection in Taiwan undergoes substantial modulation from tropical intraseasonal oscillations in the western North Pacific, including the quasi-biweekly (QBW) mode. By analyzing surface station observations and the Climate Forecast System (CFS) Reanalyses (CFSR), as well as the NCEP CFS version 2 (CFSv2) reforecast data over 18 summers from 1993 to 2010, it was found that the QBW mode plays a significant role in the formation of episodic diurnal convection. When the cyclonic circulation of the QBW mode is located west of Taiwan, followed by an anticyclonic circulation to the east, Taiwan's diurnal convection activity tends to intensify and persists for about 4–7 days. Synoptically, this situation reflects the enhanced subtropical anticyclone leading to fair weather conditions and increased monsoon southwesterly winds moistening the lower troposphere, all of which are conducive to thermally induced diurnal convection in Taiwan. The opposite situation tends to su.
Photodynamic therapy of malignant brain gliomas

Treatment of malignant gliomas of the brain remains a serious problem on a global scale, despite intensive research into the causes and mechanisms of their progression. When using traditional surgical approaches and imaging methods tumor cell infiltrates may be overlooked, as a result of which, malignant gliomas relapse often occurs near the marginal region of the surgical cavity. A method that allows visual identification of tumor tissue and at the same time provides an opportunity to selectively destroy it is photodynamic therapy (PDT) ‒ a two-stage treatment that includes the introduction (intravenous, intraperitoneal, local or oral) of a light-sensitive chemical agent (photosensitizer (PS)) followed by its activation at a certain wavelength of light.The principle of PDT is based on the cytotoxic effects caused by PS, which selectively accumulates in malignant tumor cells and is activated by light rays of the appropriate wavelength, generating singlet oxygen and free radicals, which trigger photochemical reactions in tumor cells with subsequent destruction of protein structures. Tumor tissue has a higher affinity for PSs. PSs are divided into 1st, 2nd and 3rd generation molecules. So far, 3rd generation PSs have not yet been approved for clinical use. In vitro and in vivo experimental studies confirmed the effectiveness of PDT of brain tumors using 2nd generation PSs.The simultaneous use of surgery under the control of fluorescence and PDT enables both the visualization of tumor cells and their selective destruction. Regardless of PDT, PSs are used for the purpose of auxiliary delineation of tumor borders for maximum tumor removal during fluorescence-guided surgery.The review examines the development of PDT in a historical aspect, the contribution of domestic scientists, in particular, scientists of the Institute of Neurosurgery named after acad. A. P. Romodanov, National Academy of Medical Sciences of Ukraine to the development of the problem of PDT in neuro-oncology; preclinical studies of PDT and experimental approaches to increase the efficiency of PDT are characterized. Analysis of data from clinical trials confirms that using PDT as an adjunctive treatment of malignant gliomas administered immediately after maximal resection is safe, reduces the risk of recurrence by targeting residual tumor cells in the resection cavity, improves survival and quality of life of patients. The absence of information on the development of resistance to multiple PDT sessions suggests the possibility of repeated treatments of tumor cells not removed during surgery.
Ion cyclotron emissions observed by the satellite Akebono in the vicinity of the magnetic equator

Ion wave observations by a wave measuring instrument named ELF on board the Akebono satellite, interesting ELF emissions in the frequency ranges above the cyclotron frequencies of He(+) and/or O(+) ions have been detected. It is proposed that these emissions are due to electromagnetic ion cyclotron waves, which might have been generated by the ion cyclotron resonant instability due to a temperature anisotropy of hot H(+) ions, trapped along the magnetic field lines around the geomagnetic equatorial plane. In order to confirm the characteristics of these ELF emissions, statistical characteristics, refractive index, and wave normal direction of the emissions are first estimated. The propagation characteristics of these ELF emissions are examined by ray tracing for ion cyclotron waves in the magnetosphere using both cold and hot plasma models. 18 refs.
The Initial Composition of Jet Condensation Trails

Abstract Physicochemical processes that generate and transform aerosols in jet aircraft plumes are discussed on the basis of theoretical models and recent observations of young contrails in the upper troposphere. The initial evolution of optical depth and ice water content under threshold contrail formation conditions is studied. Constrained by the measurements, a lower bound is deduced for the number density of ice crystals initially present in contrails. This bound serves as a visibility criterion for young contrails. An analysis of the primary contrail particles (aqueous solution droplets nucleated in situ, emitted insoluble combustion aerosols, and entrained background aerosols) reveals that only soot must he involved as ice forming nuclei if the visibility criterion is to be fulfilled. Possible activation pathways of the soot aerosols are investigated, including an analysis of their wetting behavior and droplet scavenging and heterogeneous nucleation properties. To support these investigations, resul.
Effects of Personal Control and Optimism on Older Adults’ Wellbeing

ABSTRACT The study examines personal control as an antecedent of optimism, which is theorized to explain older adults’ consumption-related activities and life satisfaction. Implications of these findings for marketers of products and services targeted toward older consumers are also discussed. An online survey of 267 adults, 50 years of age and older, is used to test the model of antecedents and consequence of optimism, using structural equation modeling. Results suggest that personal control is an important antecedent of optimism, which may influence several consumption-related behaviors and the well-being of older consumers.
Consumption of Energy Drinks among University Students in Eastern Croatia

The modern lifestyle today creates a certain pressure on people who are forced to adapt to such a way of living. Energy drinks (EDs), beverages containing certain stimulating ingredients, are increasingly being offered on the market. Given the unclear impact of EDs consumption on the health of the individual, the focus of this study was to determine the prevalence of EDs consumption among the student population at the University of Osijek (Eastern Croatia). The cross-sectional study via an anonymous questionnaire included 424 students, with an average age of 22.8 years. It was discovered that 52.4% of participants consume EDs. Males were significantly more likely to drink EDs than females (χ2-test; p = 0.006). They more frequently consume EDs six or more times per month (χ2-test; p = 0.045) as well as consume more EDs on one occasion (χ2-test; p < 0.001). University students who were engaged in sports or physical activity were significantly more likely to consume EDs (χ2-test; p = 0.024) as well as smokers in comparison to non-smokers (χ2-test; p = 0.034). In conclusion, the study proved the frequent consumption of EDs among Croatian university students consequently highlighting the need to raise awareness of the possible adverse effects of EDs consumption.
On the time complexity of worst-case system identification

In this paper we treat a general worst-case system identification problem. This problem is worst-case with respect to both noise and system modeling uncertainty. We consider this problem under various a priori information structures. We determine bounds on the minimum duration identification experiment that must be run to identify the plant to within a specified guaranteed worst-case error bound. Our results are algorithm independent. We show that this minimum duration is prohibitively long. Based on our results, we suggest that worst-case (with respect to noise) system identification requires unrealistic amounts of experimental data. >
Monoid kernels and profinite topologies on the free Abelian group

To each pseudovariety of Abelian groups residually containing the integers, there is naturally associated a profinite topology on any finite rank free Abelian group. We show in this paper that if the pseudovariety in question has a decidable membership problem, then one can effectively compute membership in the closure of a subgroup and, more generally, in the closure of a rational subset of such a free Abelian group. Several applications to monoid kernels and finite monoid theory are discussed.
Ortho-H2 and the age of prestellar cores

Prestellar cores form from the contraction of cold gas and dust material in dark clouds before they collapse to form protostars. Several concurrent theories exist to describe this contraction but they are currently difficult to distinguish. One major difference is the timescale involved in forming the prestellar cores: some theories advocate nearly free-fall speed via, e.g., rapid turbulence decay, while others can accommodate much longer periods to let the gas accumulate via, e.g., ambipolar diffusion. To tell the difference between these theories, measuring the age of prestellar cores could greatly help. However, no reliable clock currently exists. We present a simple chemical clock based on the regulation of the deuteration by the abundance of ortho‐H2 that slowly decays away from the ortho-para statistical ratio of 3 down to or less than 0.001. We use a chemical network fully coupled to a hydrodynamical model that follows the contraction of a cloud, starting from uniform density, and reaches a density profile typical of a prestellar core. We compute the N2D + /N2H + ratioalong the density profile. The disappearance of ortho-H2 is tied tothe duration of the contraction and the N2D + /N2H + ratio increases in the wake of the ortho-H2 abundance decrease. By adjusting the time of contraction, we obtain different deuteration profiles that we can compare to the observations. Our model can test fast contractions (from 10 4 to 10 6 cm −3 in ∼0.5 My) and slow contractions (from 10 4 to 10 6 cm −3 in ∼5 My). We have tested the sensitivity of the models to various initial conditions. The slowcontraction deuteration profile is approximately insensitive to these variations, while the fast-contraction deuteration profile shows significant variations. We found that, in all cases, the deuteration profile remains clearly distinguishable whether it comes from the fast collapse or the slow collapse. We also study the para-D2H + /ortho-H2D + ratio and find that its variation is not monotonic, so it does not discriminate between models. Applying this model to L183 (=L134N), we find that the N2D + /N2H + ratio would be higher than unity for evolutionary timescales of a few megayears independently of other parameters, such as cosmic ray ionization rate or grain size (within reasonable ranges). A good fit to the observations is only obtained for fast contraction (≤0.7 My from the beginning of the contraction and ≤4 My from the birth of the molecular cloud based on the need to keep a high ortho-H2 abundance when the contraction starts ‐ ortho-H2/para-H2 ≥ 0.2 ‐ to match the observations). This chemical clock therefore rules out slow contraction in L183 and steady-state chemical models, since steady state is clearly not reached here. This clock should be applied to other cores to help distinguish slow and fast contraction theories over a large sample of cases.
Experimental Measurement and Multiphysics Simulation of Tritium Transport in Neutron-Irradiated Flibe Salt

Abstract Predicting the distribution and release of tritium remains a technical challenge for advanced nuclear reactors with molten Flibe (2LiF-BeF2) salt coolants. Tritium transport models, which are currently used to forecast release behavior, are limited by uncertainty in Flibe-related tritium transport properties and by a lack of relevant benchmark experiments to test input parameters and solution methods. A new test facility has been developed at the Massachusetts Institute of Technology Research Reactor (MITR) to irradiate a molten Flibe target in an ex-core neutron beam port to further investigate tritium transport mechanisms at prototypical reactor conditions. The experiment monitored the time-dependent release of tritium from the salt-free surface and the permeation rate of tritium through the stainless steel Flibe-containing test stand. Measured results were benchmarked with a multiphysics tritium transport simulation to resolve complex effects in the test. Trends in tritium release rates from the irradiation were in agreement with the multiphysics simulation of the test, which combined computational fluid dynamics, radiative heat transfer in participating media, and tritium transport in STAR-CCM+.
Analyzing Mean Profiles of Nonnormal Populations

We consider testing whether the mean vectors of two or more populations have parallel, coincident, or flat profiles when the validity of normality is not known, and the sample sizes are moderate. Using some properties of multivariate moments and matrix manipulations, we obtain the asymptotic expansions for the null distribution of the Lawley–Hotelling statistics. We also derive the corresponding results in the situation where interest lies in coincidence and flatness alone. Accuracy of all the asymptotic expansions in approximating the exact null distributions is examined via simulation. Profile analysis of SO4 concentrations from a forestry experiment is used to illustrate the methods.
Cyclotron harmonics in accreting pulsars and gamma-ray bursters : effect of two-photon processes

The radiative transfer at the cyclotron first, second, and third harmonics for simplified accreting pulsar and gamma-ray burster emission regions is analyzed. Two-photon scattering as well as two-photon emission, which play a major role in determining the line-strength ratio, are included. Stimulated effects are also important for accurately modeling the optically thick line and continuum regions. These calculations are compared with recent observations of accreting pulsars and gamma-ray burst sources, showing a qualitative agreement. It is found that the cyclotron harmonic lines should be strongly polarized.
Current limiting effects of photoactivated charge domain in semi-insulating GaAs photoconductive switch

The photoactivated charge domain (PACD) plays an important role in the nonlinear modes of semi-insulating GaAs and LnP photoconductive switches. The formation and transporting process of photoactivated charge domain are discussed in this paper, which indicate that it is the shielded electric field that induced the unique distribution and evolution law of the PACD. The PACD restricts space-charge current in the photoconductor and the output current of the photoconductive switch by its shielded effect.