In this study, five ice shapes generated at NASA Glenn's Icing Research Tunnel (IRT) are simulated at multiple angles of attack 1. These geometries target different icing environments, both ...early-time and longer-duration glaze and rime ice exposure events, including a geometry that results from using a thermal ice-protection system. Using the laser-scanned geometries, detailed representations of the three-dimensional ice geometries are resolved on the grid and simulated using wall-modeled LES. Integrated loads (lift, drag, and moment coefficients) and pressure distributions are compared against experimental measurements in both clean and iced conditions for several angles of attack in both pre- and post-stall regions. The relevant comparisons to the experimental results show that qualitative and acceptable quantitative agreement with the data is observed across all geometries.
Glaze ice formations exhibit larger and highly nonuniform ice features, such as ‘horns’, in contrast to rime ice formations characterized by smaller, uniformly distributed roughness elements. In wall-modeled LES, it was observed that larger roughness scales in the glaze ice that trigger transition can be accurately resolved. Therefore, it is possible for WMLES to accurately capture the aerodynamics of glaze ice shapes without the need for additional modeling. In contrast, rime ice geometries required additional resolution to accurately represent the aerodynamic loads. This study demonstrates the effectiveness of the wall-modeled LES technique in simulating the complex aerodynamic effects of iced airfoils, providing valuable insights for aircraft design in icing environments and highlighting the importance of accurately representing ice geometries and roughness scales in simulations.
We present the results of a short-term longitudinal study. Children in the early stages of learning to read (5 and 6 year olds) were administered three different tasks (deletion, oddity, and ...detection) tapping awareness of four phonological units (initial phoneme, final phoneme, onset, and rime). Measures of phoneme awareness were the best concurrent and longitudinal predictors of reading skill with onset-rime skills making no additional predictive contribution once phonemic skills were accounted for. The findings are related to recent controversy over the role of large versus small phonological units as predictors of children's reading skills.
Cadmium (Cd) and its forms has recently been a focus of attention due to its toxic effects on human health and the environment. We evaluated the atmospheric deposition of Cd during three consecutive ...winter seasons (2009–2011) at 10 mountain-top locations in the Czech Republic along the borders with Poland, Germany, Austria and Slovakia. Cadmium concentrations of soluble and insoluble forms in both horizontal (rime) and vertical (snow) deposition were determined using sector-field ICP-MS. Across the sites, 94% of the total winter Cd deposition occurred in the soluble (environmentally available) Cd form. Mean concentrations of soluble Cd in rime were six times higher than in snow (398 vs. 66 ng L−1). Vertical deposition contributed as much as 41% to the total winter Cd input. Between-site variability in Cd deposition was large, ranging between 13 and 108 μg m−2 winter−1. Overall, Cd concentrations in winter deposition did not reach the drinking water limits and did not pose a direct threat for human health. Long-term trends (1996–2017) in winter Cd deposition were evaluated at six GEOMON sites (a monitoring network of small forested catchments). Since 1996, Cd input in winter atmospheric deposition decreased by 73–93%. Simultaneously, we found declines in between-site variability in winter Cd inputs. The highest recent winter Cd inputs were found at sites located in the northeast of the country. A north-south pollution gradient, which has frequently been mentioned in the literature, was not observed, with both northwestern sites and southern sites being among those with the lowest Cd pollution. Backward trajectories of the HYSPLIT model for fresh snow samples identified Poland and Germany as major transboundary Cd pollution sources for the Czech Republic.
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•94% of Cd in winter deposition occurred in the soluble form.•Rime contributed >40% of the total atmospheric Cd input.•Mean concentrations of soluble Cd in rime were six times higher than in snow.•Cd in winter atmospheric deposition at mountain-top sites differed up to 8 times.•Between 1996 and 2017, Cd input in winter deposition decreased by 73–93%.
Gametocyte development is a critical step in the life cycle of Plasmodium. Despite the number of studies on gametocyte development that have been conducted, the molecular mechanisms regulating this ...process remain to be fully understood. This study investigates the functional roles of two female-specific transcriptional regulators, PbAP2-FG2 and PbAP2R-2, in P. berghei. Knockout of pbap2-fg2 or pbap2r-2 impairs female gametocyte development, resulting in developmental arrest during ookinete development. ChIP-seq analyses of these two factors indicated their colocalization on the genome, suggesting that they function as a complex. These analyses also revealed that their target genes contained a variety of genes, including both male and female-enriched genes. Moreover, differential expression analyses showed that these target genes were upregulated through the disruption of pbap2-fg2 or pbap2r-2, indicating that these two factors function as a transcriptional repressor complex in female gametocytes. Formation of a complex between PbAP2-FG2 and PbAP2R-2 was confirmed by RIME, a method that combines ChIP and MS analysis. In addition, the analysis identified a chromatin regulator PbMORC as an interaction partner of PbAP2-FG2. Comparative target analysis between PbAP2-FG2 and PbAP2-G demonstrated a significant overlap between their target genes, suggesting that repression of early gametocyte genes activated by PbAP2-G is one of the key roles for this female transcriptional repressor complex. Our results indicate that the PbAP2-FG2-PbAP2R-2 complex-mediated repression of the target genes supports the female differentiation from early gametocytes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background: We evaluate the effectiveness of three theoretically motivated programmes for the teaching of reading to four‐year‐old children.
Method: Four hundred and ten children, of ...pre‐kindergarten age, in 20 UK Reception‐year classrooms were divided into four matched groups and randomly assigned to one of three experimental teaching conditions, Reading with Rhyme, Reading with Phoneme, Reading with Rhyme and Phoneme, or to a taught control condition (Reading). In each condition the Reading element contained a strong phonic component.
Results: There were no selective effects of the different experimental teaching programmes for normally developing children. However, for those children identified as being at risk of reading failure, training in phoneme skills resulted in selective gains in phoneme awareness and in reading skills.
Conclusions: A reading programme that contains a highly structured phonic component is sufficient for most 4.5‐year‐old children to master the alphabetic principle and to learn to read effectively, without additional explicit phonological training. In contrast, for young children at risk of reading delay, additional training in phoneme awareness and linking phonemes with letters is beneficial.
Due to the nonlinearity, fluctuation, and intermittency of wind speed, its accurate prediction is essential for improving efficiency in wind power operation systems. In this regard, a hybrid model ...that combines the rime optimization algorithm (RIME), variational mode decomposition (VMD), multi-headed self-attention (MSA) mechanism and long short-term memory (LSTM) is proposed for wind speed prediction. First, the number of modes and VMD penalty parameter are optimized with RIME, the optimized parameters are brought into the VMD to decompose the raw wind speeds, and a Lagrange multiplier and quadratic penalty function are introduced to obtain the input series. Then, a LSTM short-term wind speed prediction model is constructed based on the MSA mechanism and solved for the hidden states and weights of each layer of attention in the model. Finally, a ReLU activation function is used to activate the hidden states of the LSTM model, and a weighted sum vector is used as the final sequence representation, which is inputted to the output layer for specific prediction to obtain the short-term wind speed prediction results. To verify the effectiveness of the proposed model, wind speed data from four wind farms in Ningxia, China, and two sets of wind speed data from an M2 tower in the USA are selected, and 19 models are built to compare the performance of the proposed model. The results show that the proposed model outperforms other models on all datasets in terms of all five performance metrics, with smaller errors and higher prediction accuracy.
•Tuning the parameters of the VMD by the RIME optimization algorithm.•Proposing a new MSA-LSTM module to prevent long-range dependencies.•An MSA is introduced to the LSTM input and to enhance sequence correlation.•The stability and robustness of the method are verified in different experiments.•The model was validated using six sets of data with different characteristic wind speeds.
Rime is an under-researched pathway of atmospheric deposition of ecological and environmental relevance, in particular in mountain regions. We present data on sulphur (S) deposition via rime and snow ...collected at 10 mountaintop sites in the Czech Republic (CR) during three consecutive winters (2009–2011). The mean S concentrations in rime ranged between 3.35 mg L−1 site Tetrevec (TET) in the north and 0.78 mg L−1 site Kamena Loucka (LOU) in the south. The most S-polluted site thus had S concentrations in rime that were approximately four times higher than the least S-polluted site. Across the sites, S concentrations in rime were 5–10 times higher than in snow. TET, identified as the most S-polluted site, received as much as 60% S from rime and only 40% S from snow. Our results indicated a substantial decline in S rime deposition since the 1990s, following the introduction of desulphurisation measures in the CR. The results of direct measurements of winter-time S deposition via rime are discussed in the context of annual occult deposition, including both rime and fog, obtained from a data-driven geostatistical model. According to our model, occult S deposition ranged between 0 and 1.5 g m−2 year−1 over 99.7% of the forested area of the CR, and generally increased with altitude. At nine sites, the winter-time deposition of S via rime corresponded to 5–13% of annual wet-only S deposition, while it reached 25% at the most S-polluted TET site. In environmental studies, the S deposition pathway via rime should not be neglected, as it might substantially contribute to the total S deposition flux even in mountains of medium elevation.
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•Sulphur deposition in rime and snow measured at 10 mountaintops in 2009–2011 winters.•Sulphur contents in rime were 5–10 times higher as compared to snow at all sites.•Measured data presented in context of data-driven modelled occult sulphur deposition.•Substantial decline of S rime deposition since the 1990s indicated.•Rime contributes to sulphur deposition substantially in mountains of medium elevation.
Wind turbine blades are prone to icing under cold conditions, and the associated changes of blade airfoil geometry have a substantial impact on the aerodynamic characteristics and output power of an ...offshore floating wind turbine. Taking a 5 MW offshore floating wind turbine as the research object, and with consideration of marine meteorological conditions in a cold region, this study used fluid mechanics to predict icing on wind turbine blades. The influence on the aerodynamic performance of the blade airfoil by rime icing-related changes in its geometric shape was investigated, and the associated change in power production of a floating wind turbine was analyzed using blade element momentum theory. When the wind turbine blade condensed rime ice, the results showed that iced airfoil geometry was reasonably regular over a short period, and that icing was concentrated primarily in the tip area of the NACA64_A17 airfoil. The change of wind speed has a certain influence on the rime icing, and the temperature variation has little effect. Airfoil geometry change after icing had little effect on the lift coefficient (maximum decrease: ∼34%) but had greater impact on the drag coefficient (increase: 36%–200%). The power production of a wind turbine with an iced airfoil was approximately 17% lower than that of a wind turbine with a clean airfoil.
•Numerical analysis of aeroelastic–hydrodynamic coupling for offshore floating wind Turbine.•Study the main icing area of wind turbine blades under cold conditions.•Analyze the influence of blade icing on the output power of offshore floating wind turbines.
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