Correlation of transonic-cone preston-tube data and skin friction

Preston-tube measurements obtained on the Arnold Engineering Development Center (AEDC) Transition Cone have been correlated with theoretical skin friction coefficients in transitional and turbulent flow. This has been done for the NASA Ames 11-Ft Transonic Wind Tunnel (11 TWT) and flight tests. The developed semi-empirical correlations of Preston-tube data have been used to derive a calibration procedure for the 11 TWT flow quality. This procedure has been applied to the corrected laminar data, and an effective freestream unit Reynolds number is defined by requiring a matching of the average Preston-tube pressure in flight and in the tunnel. This study finds that the operating Reynolds number is below the effective value required for a match in laminar Preston-tube data. The distribution of this effective Reynolds number with Mach number correlates well with the freestream noise level in this tunnel. Analyses of transitional and turbulent data, however, did not result in effective Reynolds numbers that can be correlated with background noise. This is a result of the fact that vorticity fluctuations present in transitional and turbulent boundary layers dominate Preston-tube pressure fluctuations and, therefore, mask the tunnel noise eff ects. So, in order to calibrate the effects of noise on transonic wind tunnel tests only laminar data should be used, preferably at flow conditions similar to those in flight tests. To calibrate the effects of transonic wind-tunnel noise on drag measurements, however, the Preston-tube data must be supplemented with direct measurements of skin friction

Correlation of Preston-tube data with laminar skin friction (Log No. J12984)

Preston tube data within laminar boundary layers obtained on a sharp ten-degree cone in the NASA Ames eleven-foot transonic wind tunnel are correlated with the corresponding values of theoretical skin friction. Data were obtained over a Mach number range of 0.30 to 0.95 and unit Reynolds numbers of 9.84, 13.1, and 16.4 million per meter. The rms scatter of skin friction coefficient about the correlation is of the order of one percent, which is comparable to the reported accuracy for calibrations of Preston tubes in incompressible pipe flows. In contrast to previous works on Preston tube/skin friction correlations, which are based on the physical height of the probe's face, this satisfactory correlation for compressible boundary layer flows is achieved by accounting for the effects of a variable "effective" height of the probe. The coefficients, which appear in the correlation, are dependent on the particular tunnel environment. The general procedure can be used to define correlations for other wind tunnels

Diversity and Specialization in Collaborative Swarm Systems

This paper addresses qualitative and quantitative diversity and specialization issues in the frame- work of self-organizing, distributed, artificial systems. Both diversity and specialization are obtained via distributed learning from initially homogeneous swarms. While measuring diversity essentially quantifies differences among the individuals, assessing the degree of specialization implies to correlate the swarm’s heterogeneity with its overall performance. Starting from a stick-pulling experiment in collective robotics, a task that requires the collaboration of two robots, we abstract and generalize in simulation the task constraints to k robots collaborating sequentially or in parallel. We investi- gate quantitatively the influence of task constraints and type of reinforcement signals on diversity and specialization in these collaborative experiments. Results show that, though diversity is not explicitly rewarded in our learning algorithm and there is no explicit communication among agents, the swarm becomes specialized after learning. The degree of specialization is affected strongly by environmental conditions and task constraints, and reveals characteristics related to performance and learning in a more consistent and clearer way than diversity does

Learning and Measuring Specialization in Collaborative Swarm Systems

This paper addresses qualitative and quantitative diversity and specialization issues in the framework of selforganizing, distributed, artificial systems. Both diversity and specialization are obtained via distributed learning from initially homogeneous swarms. While measuring diversity essentially quantifies differences among the individuals, assessing the degree of specialization implies correlation between the swarm’s heterogeneity with its overall performance. Starting from the stick-pulling experiment in collective robotics, a task that requires the collaboration of two robots, we abstract and generalize in simulation the task constraints to k robots collaborating sequentially or in parallel. We investigate quantitatively the influence of task constraints and types of reinforcement signals on performance, diversity, and specialization in these collaborative experiments. Results show that, though diversity is not explicitly rewarded in our learning algorithm, even in scenarios without explicit communication among agents the swarm becomes specialized after learning. The degrees of both diversity and specialization are affected strongly by environmental conditions and task constraints. While the specialization measure reveals characteristics related to performance and learning in a clearer way than diversity does, the latter measure appears to be less sensitive to different noise conditions and learning parameters

The Role of Strategic Leadership in Activating Time Management Strategies to Enhance Administrative Creativity Skills

This study aimed to identify the role of strategic leadership in activating time management strategies to enhance administrative creativity skills at Al-Azhar University. The sample of the study was random stratified sample from (245) administrative employees using questionnaire as a main tool for primary data collection. Total respondent were (112) questioners. Descriptive and quantitative approach used in this study. The general results of the study showed high levels of strategic leadership at Al-Azhar University, average level of application of time management strategies and administrative creativity. This means there is acceptance approval that there is a statistically significant relationship between strategic leadership and time management strategies in Palestinian universities in Gaza Strip with a correlation level (0.724). Also, there is a statistically significant relationship between time management strategies and administrative creativity in Palestinian universities in Gaza Strip under study with a correlation level (0.848). According to static analysis, there is a statistically significant relationship between the dimensions of strategic leadership and administrative creativity in Palestinian universities in Gaza Strip under study, with a level of correlation (0.767%). This leases to high investment process for all available factors and elements in order to maximize and increase production and eliminate waste, wasted and unexploited employees' time and capabilities, which leads to achieving more effectiveness, positivity, productivity and increased organized effort. The study recommended necessity of having the elements of strategic academic leadership and activating time management strategies towards enhancing administrative creativity among workers in Palestinian universities in Gaza Strip. Also study recommended to encourage, support, and reward personal initiatives and creative ideas. Also study recommended available of wise and conscious strategic leadership to rationalize the behavior of individuals, mobilize their energies, mobilize their capabilities, coordinate their efforts, organize their affairs and direct them in the right direction towards achieving the desired goals and objectives

Numerical Study of the Behaviour of Embankment Constructed over Soft Soil Stabilized with Ordinary and Geosynthetic - Reinforced Stone Columns

Structures constructed on soft soils may undergo significant settlement, local or global instability, and a significant lateral displacement of the soft soil layer. Ordinary stone columns (OSC) and stone columns strengthened with geosynthetic reinforcement reduce settlement and improve the subsoil's bearing capacity. Numerical analyses have been performed using a 3-dimensional finite element program (PLAXIS3D) to investigate the time-dependent behavior of embankments resting on stone columns constructed in very soft clay. The geosynthetic encasement is the more typical type of reinforcement; however, laminated layers can be adopted in this study. The geosynthetics material was used to strengthen the OSC in the form of vertical encasement, horizontal stripes, and combined vertical-horizontal reinforcement and vertical-basal geogrid reinforcement (BGR). This research compares these forms of reinforcement on embankment behavior. The research results showed that using the encased stone column (ESC) and the vertical-horizontal reinforced stone columns (V-HRSC) have provided a considerable improvement in the lateral deformation of the column over its length, generation, and dissipation of excess pore pressure, and settlement. An increase in factor of safety (FOS) against failure of the embankment was observed by 53% using the ESC compared to untreated soil. Using the horizontal geosynthetic layer (HGL) and the (BGR) after encasing the stone columns has no effect on the safety factor as the failure mechanism converted from deep-seated to surface failure

Wound healing and antioxidant properties of <i>Launaea procumbens</i> supported by metabolomic profiling and molecular docking

Wounds adversely affect people’s quality of life and have psychological, social, and economic impacts. Herbal remedies of Launaea procumbens (LP) are used to treat wounds. In an excision wound model, topical application of LP significantly promoted wound closure (on day 14, LP-treated animals had the highest percentages of wound closure in comparison with the other groups, as the wound was entirely closed with a closure percentage of 100%, p < 0.05). Histological analysis revealed a considerable rise in the number of fibroblasts, the amount of collagen, and its cross-linking in LP-treated wounds. Gene expression patterns showed significant elevation of TGF-β levels (2.1-fold change after 7 days treatment and 2.7-fold change in 14 days treatment) and downregulation of the inflammatory TNF-α and IL-1β levels in LP-treated wounds. Regarding in vitro antioxidant activity, LP extract significantly diminished the formation of H(2)O(2) radical (IC(50) = 171.6 μg/mL) and scavenged the superoxide radical (IC(50) of 286.7 µg/mL), indicating antioxidant potential in a dose-dependent manner. Dereplication of the secondary metabolites using LC-HRMS resulted in the annotation of 16 metabolites. The identified compounds were docked against important wound-healing targets, including vascular endothelial growth factor (VEGF), collagen α-1, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and transforming growth factor-β (TGF-β). Among dereplicated compounds, luteolin 8-C-glucoside (orientin) demonstrated binding potential to four investigated targets (VEGF, interleukin 1β, TNF-α, and collagen α-1). To conclude, Launaea procumbens extract could be regarded as a promising topical therapy to promote wound healing in excisional wounds, and luteolin 8-C-glucoside (orientin), one of its constituents, is a potential wound-healing drug lead