Numerical analysis on the oscillation of stall cells over a NACA 0012 aerofoil

A series of three-dimensional unsteady Reynolds-averaged Navier-Stokes (RANS) simulations are conducted to investigate the formation and oscillation of stall cells over a NACA 0012 aerofoil. The simulations are conducted with various physical and numerical conditions, such as the Reynolds number, angle of attack, chord-to-span ratio and span-wise mesh resolution. Results show a clear relationship between the oscillation of stall cells and the fluctuation of lift (observed between 17 and 19.5° angle of attack at a high chord Reynolds number of one million). This unsteadiness shows some dependency on the span-wise mesh resolution, which is significant with a medium span-wise mesh resolution (corresponding to 10% of the chord) and moderate with finer resolutions (corresponding to 5% and 2.5% of the chord, respectively). In addition, a proper orthogonal decomposition (POD) method is adopted to further analyse the oscillatory characteristics of stall cells. In particular, it is shown that the first few POD modes have clear spatial patterns corresponding to the profile of stall cells and their time coefficients are correlated with the fluctuation of lift, further confirming the correlation between the stall cell oscillations and the lift fluctuation

Unsteady RANS simulations of strong and weak 3D stall cells on a 2D pitching aerofoil

A series of three-dimensional unsteady Reynolds-averaged Navier–Stokes (RANS) simulations are conducted to investigate the formation of stall cells over a pitching NACA 0012 aerofoil. Periodic boundary conditions are applied to the spanwise ends of the computational domain. Several different pitching ranges and frequencies are adopted. The influence of the pitching range and frequency on the lift coefficient (CL) hysteresis loop and the development of leading-edge vortex (LEV) agrees with earlier studies in the literature. Depending on pitching range and frequency, the flow structures on the suction side of the aerofoil can be categorized into three types: (i) strong oscillatory stall cells resembling what are often observed on a static aerofoil; (ii) weak stall cells which are smaller in size and less oscillatory; and (iii) no stall cells at all (i.e., flow remains two-dimensional) or only very weak oval-shaped structures that have little impact on CL. A clear difference in CL during the flow reattachment stage is observed between the cases with strong stall cells and with weak stall cells. For the cases with strong stall cells, arch-shaped flow structures are observed above the aerofoil. They resemble the Π-shaped vortices often observed over a pitching finite aspect ratio wing

Why are pollution damages lower in developed countries? Insights from high income, high-particulate matter Hong Kong

Conventional wisdom suggests that pollution damages are high in less-developed countries because they are highly polluted. Using administrative data on the universe of births and deaths, we explore the morbidity and mortality effects of gestational particulate matter exposure in high-pollution yet highly-developed Hong Kong. The effects of particulates on birthweight are large. We estimate no effect of particulates on neonatal mortality. We interpret our stark mortality results in a comparative analysis of pollution-mortality relationships across well-known studies. We provide evidence that mortality damages may be high in less-developed countries because they are less developed, not because they are more polluted

Development of Questionnaire on Emotional Labor among Primary and Secondary School Teachers

In this study, based on the analysis of existing definitions of emotional labor, operational definition of teachers' emotional labor is given and questionnaire on emotional labor among primary and secondary school teachers is developed. Research results: exploratory factor analysis shows that teacher’s emotional labor involves three dimensions including surface acting, active deep acting and passive deep acting; the questionnaire has good reliability and validity; confirmatory factor analysis shows that emotional labor questionnaire involving three factors is established, which further verifies the validity of scale on emotional labor among primary and secondary school teachers

Multiple bombesin-like peptides with opposite functions from skin of Odorrana grahami

AbstractBombesin-like peptides (BLPs) are a family of neuroendocrinic peptides that mediate a variety of biological activities. Three mature BLPs from the skin secretions of the frog Odorrana grahami were purified. Several bombesin-like peptide cDNA sequences encoding precursors of BLPs were identified from the skin cDNA library of O. grahami. This is the maximal diversity of BLPs ever found in animals. Five mature BLPs (B1–B5) based on the amino acid sequences derived from the cDNA cloning were synthesized. In the in vitro myotropic contraction experiment, all synthesized BLPs displayed a stimulating effect toward rat stomach strips, except B4 and B5 which showed the opposite effect, suggesting that certain BLPs may act as antagonists of bombesin receptors while most other BLPs act as agonists. This finding will facilitate the finding of novel bombesin receptors and novel ligands of bombesin receptors. The diversity of amphibian BLPs and their precursors were also analyzed and results suggest that amphibian BLPs and corresponding precursors of various sizes and processing patterns can be used as markers of taxonomic and molecular phylogenetics. The remarkable similarity of preproregions gives rise to very different BLPs and 3′-terminal regions in distantly related frog species, suggesting that the corresponding genes form a multigene family originating from a common ancestor. The diversification of BLP loci could thus be part of an evolutionary strategy developed by amphibian species as a result of shifts to novel ecological niches when environmental factors change rapidly

A MODEL OF FUZZY TOPOLOGICAL RELATIONS FOR SIMPLE SPATIAL OBJECTS IN GIS

The goal of this paper is to present a new model of fuzzy topological relations for simple spatial objects in Geographic Information Sciences (GIS). The concept of computational fuzzy topological space is applied to simple fuzzy objects to efficiently and more accurately solve fuzzy topological relations, extending and improving upon previous research in this area. Firstly, we propose a new definition for simple fuzzy line segments and simple fuzzy regions based on computational fuzzy topology. And then, we also propose a new model to compute fuzzy topological relations between simple spatial objects, an analysis of the new model exposes:(1) the topological relations of two simple crisp objects; (2) the topological relations between one simple crisp object and one simple fuzzy object; (3) the topological relations between two simple fuzzy objects. In the end, we have discussed some examples to demonstrate the validity of the new model, through an experiment and comparisons of existing models, we showed that the proposed method can make finer distinctions, as it is more expressive than the existing fuzzy models

P16 Methylation as an Early Predictor for Cancer Development From Oral Epithelial Dysplasia: A Double-blind Multicentre Prospective Study

AbstractBackgroundSilencing of P16 through methylation and locus deletion is the most frequent early events in carcinogenesis. The aim of this study is to prospectively determine if early P16 methylation is a predictor for oral cancer development.MethodsPatients (n=181) with mild or moderate oral epithelial dysplasia (OED) were recruited into the double blind multicentre cohort. P16 methylation was analyzed using the MethyLight assay. Progression of OEDs was monitored for a minimum 3year follow-up period.FindingsP16 methylation-informative cases (n=152) were enrolled in the prospective multicenter cohorts with an ultimate compliance of 96.7%. OED-derived squamous cell carcinomas were observed in 21 patients (14.3%) during the follow-up (median, 41.0months). The cancer progression rate from the P16 methylation-positive patients was significantly increased when compared to P16 methylation-negative patients [27.1% vs 8.1%; adjusted odds ratio=4.6; P=0.006]. When the P16 methylation-positive criteria were used as a biomarker for early prediction of cancer development from OEDs, sensitivity and specificity of 62% and 76% were obtained, respectively.InterpretationP16 methylation is unequivocally a marker for determining the malignant potential of OED and there is no need for further research regarding this aspect.FundingNational Basic Research Programs of China (2011CB504201 and 2015CB553902), Beijing Science and Technology Commission (Z090507017709016), and Beijing Municipal Administration of Hospital (XM201303) to Dajun Deng. The funding agencies have no role in the actual experimental design, patient recruitment, data collection, analysis, interpretation, or writing of this manuscript