Miracle-dz/UniFAR-FTUs huggingface dataset:
Bubble-induced skin-friction drag reduction and the abrupt transition to air-layer drag reduction

To investigate the phenomena of skin-friction drag reduction in a turbulent boundary layer (TBL) at large scales and high Reynolds numbers, a set of experiments has been conducted at the US Navy's William B. Morgan Large Cavitation Channel (LCC). Drag reduction was achieved by injecting gas (air) from a line source through the wall of a nearly zero-pressure-gradient TBL that formed on a flat-plate test model that was either hydraulically smooth or fully rough. Two distinct drag-reduction phenomena were investigated; bubble drag reduction (BDR) and air-layer drag reduction (ALDR). The streamwise distribution of skin-friction drag reduction was monitored with six skin-friction balances at downstream-distance-based Reynolds numbers to 220 million and at test speeds to 20.0ms−1. Near-wall bulk void fraction was measured at twelve streamwise locations with impedance probes, and near-wall (0 < Y < 5mm) bubble populations were estimated with a bubble imaging system. The instrument suite was used to investigate the scaling of BDR and the requirements necessary to achieve ALDR. Results from the BDR experiments indicate that: significant drag reduction (>25%) is limited to the first few metres downstream of injection; marginal improvement was possible with a porous-plate versus an open-slot injector design; BDR has negligible sensitivity to surface tension; bubble size is independent of surface tension downstream of injection; BDR is insensitive to boundary-layer thickness at the injection location; and no synergetic effect is observed with compound injection. Using these data, previous BDR scaling methods are investigated, but data collapse is observed only with the ‘initial zone’ scaling, which provides little information on downstream persistence of BDR. ALDR was investigated with a series of experiments that included a slow increase in the volumetric flux of air injected at free-stream speeds to 15.3ms−1. These results indicated that there are three distinct regions associated with drag reduction with air injection: Region I, BDR; Region II, transition between BDR and ALDR; and Region III, ALDR. In addition, once ALDR was established: friction drag reduction in excess of 80% was observed over the entire smooth model for speeds to 15.3ms−1; the critical volumetric flux of air required to achieve ALDR was observed to be approximately proportional to the square of the free-stream speed; slightly higher injection rates were required for ALDR if the surface tension was decreased; stable air layers were formed at free-stream speeds to 12.5ms−1 with the surface fully roughened (though approximately 50% greater volumetric air flux was required); and ALDR was sensitive to the inflow conditions. The sensitivity to the inflow conditions can be mitigated by employing a small faired step (10mm height in the experiment) that helps to create a fixed separation line.
Elemental abundance analyses with DAO spectrograms: XXXII. HR 6455 (A3 III), δ Aqr (A3 V), η Lep (F2 V), and 1 Boo (A1 V)

We examine the sharp-lined stars HR 6455 (A3 III, v sin i = 8.7 km s–1) and η Lep (F2 V, v sin i = 13.5 km s–1) as well as δ Aqr (A3 V, v sin i = 81 km s–1) and 1 Boo (A1 V, v sin i = 59 km s–1) to increase the number consistently analyzed A and F stars using high dispersion and high S/N (≥200) spectrograms obtained with CCD detectors at the long Coude camera of the 1.22-m telescope of the Dominion Astrophysical Observatory. Such studies contribute to understanding systematic abundance differences between normal and non-magnetic main-sequence band chemically peculiar A and early F stars. LTE fine analyses of HR 6455, δ Aqr, and 1 Boo using Kurucz's ATLAS suite programs show the same general elemental abundance trends with differences in the metal richness. Light and iron-peak element abundances are generally solar or overabundant while heavy element and rare earth element abundances are overabundant. HR 6455 is an evolved Am star while δ Aqr and 1 Boo show the phenomenon to different extents. Most derived abundances of η Lep are solar (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Ensemble prediction of tropical cyclones using targeted diabatic singular vectors

The feasibility of using the European Centre for Medium‐Range Weather Forecasts's ensemble prediction system for tropical‐cyclone prediction is studied in terms of the spread in cyclone tracks and intensities. It is shown that significant spread in the tracks is obtained through the use of initial perturbations based on targeted singular vectors derived using linearized physics. Inclusion of stochastic physics in the forecast model leads to larger spread in the central pressures. The spread in the tracks shows a high level of sensitivity to the background state used in deriving the singular vectors.
EFFECT OF USING DENTATE SKI JUMP SPILLWAYS ON SCOURING

Flip buckets or ski jumps are known as the most economical design for energy dissipation at high dams. The dissipation of energy does not take place in the bucket itself (except at low flows) but in the air and in the river bed where severe erosion can be expected. Flip buckets have been designed in various shapes and forms. The main criterion in design of all types of flip buckets is: to discharge the flow from the spillway into the river as far as possible so as to achieve the greatest jet dispersion possible at all discharges. Experience shows that using dentate splitters on the ski jump spillways can effectively reduce scouring depth and its development in downstream plunge pool. In this paper, effect of using dentate ski jump spillways was investigated in a 1/50 scale comprehensive model of a concrete gravity arch dam built in a narrow and deep gorge. The model test investigations carried out in hydraulic laboratory of Water Research Institute to optimize the best shape of ski jumps. The model studies was based on a comparison between conventional bucket type (CB) with continuous solid lip of angles 0 and 20 and a 5 teeth dentate (toothed) bucket (DB). The jet flow patterns were observed and the scouring profiles on the river bed along the bucket axis were measured. Results showed that dentate buckets can effectively reduce ultimate depth of scour hole and the potential of erosion which may be expressed by volume of eroded materials.
VICONOPT: Program for Exact Vibration and Buckling Analysis or Design of Prismatic Plate Assemblies

ASUMMARY is given of key features of the computer program VICONOPT,1 which covers prismatic assemblies of anisotropic plates exactly for buckling and vibration analysis and also for design subject to buckling constraints. Contents VICONOPT (VIpasa with CONstraints and OPTimization) is a 23,000 line Fortran 77 computer program that incorporates the earlier programs VIPASA2 and VICON.3 It covers any prismatic assembly of anisotropic plates and Fig. 1 shows typical cross sections. Each plate can carry any combination of NL, NT9 and Ns, the longitudinally invariant in-plane forces per unit length of plate edge shown in Fig. 1. VICONOPT performs analysis or optimum design. The analysis includes calculation of critical buckling load factors, or undamped natural frequencies, and mode shapes. VIPASA uses the stiffness matrix method based on exact flat plate theory with Winkler foundations. It also uses an algorithm that guarantees convergence on all required eigenvalues and permits the user to employ nested (to any level) substructuring very concisely and flexibly to reduce solution times, data preparation, and computer memory usage. The mode of buckling or vibration is assumed to vary sinusoidally in the longitudinal direction x> with the displacement amplitudes u, v, w, and ^ shown in Fig. 1 and with computations being repeated for a user specified set of half-waveleng ths X. Plate bending and membrane behaviors are uncoupled and the bending and in-plane stiffness matrices D and A are respectively fully populated and orthotropic, which treats balanced symmetric laminates. The global stiffness matrix becomes complex when anisotropy or shear loading are present, thus, increasing solution time. The nodal lines of zero displacement are straight and in the y direction if all plates are orthotropic with Ns = 0, and so satisfy simply supported end conditions. Otherwise, solutions only approximate such end conditions and become excessively conservative as A approaches L Dead load values of NL, NT9 and Ns are permitted for both buckling and vibration problems. In the former case they are additional to live load values that are factored until buckling occurs. Plate loadings may be given as data, although NL is usually calculated from the total longitudinal load on the panel or
Complex permittivities of breast tumor tissues obtained from cancer surgeries

The variability in measurements of complex permittivities of tumor tissues between multiple samples could be attributed to the volume fraction of cancer cells in the excised tumor tissue. By the use of a digital photomicrograph image and hematoxylin-eosin staining, it was found that the malignant tumor tissue was not fully occupied by the cancer cells, but the cells were distributed locally in the stroma cells depending on the growth of cancer. The results showed that the volume fraction of cancer cells in the tumor tissue had a correlation to the measured conductivity and dielectric constant in the frequency range from 1 GHz to 6 GHz. It introduces a method to understand and gauge variability in measurements between different tumors.
Gerontechnology acceptance of smart homes: A systematic review and meta-analysis

Advances in preventive medicine and technology have beneficially affected longevity in the past decades. Unfortunately, longer life expectancy and declining fertility are likely to trigger an increasingly aging population, posing new challenges for social systems. Since aging populations affect the healthcare industry, providing convenient solutions and user-friendly elderly healthcare services is necessary to curb the growing demand by older adults. Several studies have proposed intelligent homes as potential solutions to support old age. However, such solutions raise the question of whether or not elderly persons intend to use smart homes and benefit from them. This paper examines the gerontechnology acceptance of intelligent homes by systematically reviewing previous studies on older people's intention to use innovative home technology. The review was conducted from the Web of Science, Google Scholar, and Scopus, retrieving a thousand articles. Out of these, 40 are selected for the meta-analysis and systematic review. The integrative results showed an increasing intention of older adults to use smart home technology as they believe those innovative ways may improve independent living. However, attributes and drivers like privacy and perceived security show increasing heterogeneity and should draw more attention to prospective researchers.
Open and Closed Mathematics: Student Experiences and Understandings

This paper reports on 3-year case studies of 2 schools with alternative mathematical teaching approaches. One school used a traditional, textbook approach; the other used open-ended activities at all times. Using various forms of case study data, including observations, questionnaires, interviews, and quantitative assessments, I will show the ways in which the 2 approaches encouraged different forms of knowledge. Students who followed a traditional approach developed a procedural knowledge that was of limited use to them in unfamiliar situations. Students who learned mathematics in an open, project-based environment developed a conceptual understanding that provided them with advantages in a range of assessments and situations. The project students had been “apprenticed” into a system of thinking and using mathematics that helped them in both school and nonschool settings.
Validation of the Rain Profiling Algorithm “ZPHI” from the C-Band Polarimetric Weather Radar in Darwin

Abstract An extensive application of a rain profiling algorithm (ZPHI) employing a C-band polarimetric radar (the C-POL radar of the Australian Bureau of Meteorology Research Centre in Darwin) is presented. ZPHI belongs to the class of rain profiling algorithms that have been developed for spaceborne or airborne radars operating at attenuating frequencies. By nature, these algorithms are nonlocal: the full profile of the measured radar reflectivity is inverted to derive a retrieved profile of the rainfall rate. The retrieval accuracy lays in the imposition of an “external constraint” in the inversion procedure. In this case, that is supplied by the differential phase shift ΦDP. The primary products of ZPHI are the profile along the beam of the specific attenuation A, and the “normalized” intercept parameter N*0. The rainfall rate is further estimated through an R–A relation adjusted for N*0. ZPHI solves automatically two problems met when operating at C band: the along-path attenuation and the variability.
A hydrodynamic analysis of flagellar propulsion

Numerical results are presented for planar sinusoidal waves (amplitude α, wave-number k). The average swimming speed and power consumption are computed for a wide range of the parameters. The optimal sine wave for minimizing power consumption is found to be a single wave with amplitude αk ≈ 1. The power consumption is found to be relatively insensitive to changes in the flagellar radius. The optimal flagellar length is found to be in the range L/A = 20–40. The instantaneous force distribution and flow field for a typical organism are presented. The trajectory of the organism through one cycle shows that a wave of constant amplitude may have the appearance of increasing amplitude owing to the yawing motion of the organism. The results are compared with those obtained using resistance coefficients. For organisms with small cell bodies (A/L = 0.05), the average swimming speed predicted by Gray-Hancock coefficients is accurate to within 10%. For large cell bodies (A/L = 0.2), the error in swimming speed is approximately 20%. The relative error in the predicted power consumption is 25–50%. For the coefficients suggested by Lighthill, the power is consistently underestimated. The Gray-Hancock coefficients underestimate the power for small cell bodies and overestimate it for large cell bodies.
Photonic crystal LEDs – designing light extraction

Photonic crystals (PhCs) have attracted much attention during the last decade as a solution to overcome the low extraction efficiency of as‐grown light‐emitting diodes (LEDs). In this review we describe the underlying physics and summarize recent results obtained with PhC LEDs. Here, the main focus is on diffracting PhC. In order to quantify the benefit from the incorporation of PhCs for diffracting light a comparison by simulations between a PhC LED and a standard state‐of‐the‐art LED is carried out. Finally, the impact of the PhC on the LEDs emission characteristics will be discussed with respect to étendue‐limited applications.
The propagator for quantum mechanics on a group manifold from an infinite-dimensional analogue of the Duistermaat-Heckman integration formula

An exact expression for the quantum mechanical propagator for a particle moving on a group manifold is shown to arise from the application of an infinite-dimensional version of the Duistermaat-Heckman integration formula to a suitable path integral over the based loop group of the group. In an appendix the equivalence of this expression to a spectral representation of the propagator is demonstrated by means of a Poisson resummation.
Well-posedness of the Navier—Stokes—Maxwell equations

We study the local and global well-posedness of a full system of magnetohydrodynamic equations. The system is a coupling of the incompressible Navier—Stokes equations with the Maxwell equations through the Lorentz force and Ohm's law for the current. We show the local existence of mild solutions for arbitrarily large data in a space similar to the scale-invariant spaces classically used for Navier—Stokes. These solutions are global if the initial data are small enough. Our results not only simplify and unify the proofs for the space dimensions 2 and 3, but also refine those in [8]. The main simplification comes from an a prioriLt2 (Lx∞) estimate for solutions of the forced Navier—Stokes equations.
xogenous testosterone in women enhances and inhibits competitive ecision-making depending on victory – defeat experience and trait ominance

The present experiment tested the causal impact of testosterone on human competitive decision-making. According to prevailing theories about testosterone’s role in social behavior, testosterone should directly boost competitive decisions. But recent correlational evidence suggests that testosterone’s behavioral effects may depend on specific aspects of the context and person relevant to social status (win–lose context and trait dominance). We tested the causal influence of testosterone on competitive decisions by combining hormone administration with measures of trait dominance and a newly developed social competition task in which the victory–defeat context was experimentally manipulated, in a sample of 54
A Nominal Response Model Approach for Detecting Answer Copying

When examinees copy answers to test questions from other examinees, the validity of the test is compromised. Most available statistical procedures for detecting copying were developed out of classical test theory (CrT); hence, they suffer from sampledependent score and item statistics, and biased estimates of the expected number of answer matches between a pair of examinees. Item response theory (IRT) based procedures alleviate these problems; however, because they fail to compare the similarity of responses between neighboring examinees, they have relatively poor power for detecting copiers. A new IRT-based test statistic, wo, was compared with the best CUT-based index g2 under various copying conditions, amounts of copying, test lengths, and sample sizes. w consistently held the Type I error rate at or below the nominal level; g2 yielded substantially inflated Type I error rates. The power of w varied as a function of both test length and the percentage of items copied. w demonstrated good power to detect copiers, provided that at least 20% of the items were copied on an 80-item test and at least 30% were copied on a 40-item test. Based on these results, with regard to both Tbype I error rate and power, c appears to be more useful than g2 as a copying index.
Discrete-time inverse model-based iterative learning control: stability, monotonicity and robustness

This paper considers the robustness of an inverse iterative learning control algorithm. A simple learning gain results in robust convergence that is monotonic in the least squares sense provided that the multiplicative plant uncertainty satisfies a matrix positivity requirement. The results are extended to the frequency domain using a simple graphical Nyquist test. The analysis extends naturally to a parameter-optimal control setting. Non-monotone convergence is considered by using a simple weighted norm based on exponential weighting of time series.
Key factors of adopting energy management systems in building sector in Taiwan

It is no doubt the world is experiencing global warming and human emission causes distinct climate change. According to the analysis from International Energy Agency, the over consumed nature resources from power, industry, transport and building sectors are off the major factors reflecting on the essential greenhouse gases to life. As moving onto the smart technology and smart grid development, recent studies indicate that using the advanced energy management systems is critical to improve power efficiency, energy saving, and reduce greenhouse gas emission. This study relies on a systematic literature review and expert opinion to identify the critical factors of adoption building energy management system. Finally, a framework is presented to evaluate the introduction of energy management systems in the construction field in order to achieve zero carbon ready buildings.
Research on the influencing factors of demand for elderly care services based on data of elderly care service information system

Elderly care has emerged as a pressing concern for society as a whole in the setting of global aging. The elderly care service information system can play an important role in the study of elderly care issues. This study uses Anderson's Behavioral Model and Maslow's Hierarchy of Needs Theory as the analytical framework and guide, applies multiple logistic regression analysis, and is bases on the data from the elderly care service information system to study the factors influencing the demand for elderly care services and the interaction between the influencing factors in terms of predisposing factors, enabling factors and need factors. Compared with physiological demand, age, living status and self-care ability have a significant impact on physiological demand. Environmental demands are significantly influenced by age, educational level, living status, child support situation and self-care ability, while gender does not have a significant effect on either type of demand. The main effects model fits better with the addition of the interaction term. There is a significant interaction effect between the three types of factors. Finally, this study proposes suggestions from two perspectives: the supply of elderly care services and the construction of the elderly care service information system.
Bubbles rising in line: why is the first approximation so bad?

An analytical theory is given for the viscous wake behind a spherical bubble rising steadily in a pure liquid at high Reynolds number, and for that wake's effect on the motion of a second bubble rising underneath the first. Previous theoretical work on this subject consists of just two papers: a first approximation ignoring wake vorticity diffusion between the bubbles, and a full numerical solution avoiding simplifying approximations (apart from that of spherical shape of the bubbles). A second approximation is now found; it removes much of the discrepancy between the first approximation and the full solution. The leading-order calculation of wake vorticity diffusion uses a transformation of the independent variables which appears to be new. Experimental work to date has disagreed with all the theoretical work, but it addresses a somewhat different problem: a line of many bubbles.
Asymptotic Expansions for the Moments of the Semi-Markovian Random Walk with Gamma Distributed Interference of Chance

In this study, a semi-Markovian random walk with a discrete interference of chance (X(t)) is considered and under some weak assumptions the ergodicity of this process is discussed. The exact formulas for the first four moments of the ergodic distribution of the process X(t) are obtained when the random variable ζ1, which describes a discrete interference of chance, has a gamma distribution with parameters (α, λ), α > 1, λ > 0. Based on these results, the asymptotic expansions are obtained for the first four moments of the ergodic distribution of the process X(t), as λ → 0. Furthermore, the asymptotic expansions for the skewness and kurtosis of the ergodic distribution of the process X(t) are established. Finally, it is discussed that the alternative estimations for the stationary characteristics of this process can be offered by using obtained asymptotic expansions.