Study of Flow around a Trapezoidal Model of a Small-Sized UAV into Turbulent Wake

Investigations of the structure of the flow near the surface of a trapezoidal model of a small unmanned aerial vehicle were carried out when it enters a narrow turbulent wake. All experimental data were obtained in a wind tunnel at subsonic flow velocities. A feature of the work was that the study of the flow around the model was carried out at full-scale (flight) Reynolds numbers. Using the soot-oily visualization method, data on the features of the flow around the model were obtained, taking into account such factors as the angle of attack, the presence and absence of a source of external disturbances that generated a turbulent wake. The experiments were carried out in two flow regimes: at a zero angle of attack, when there are local separation bubbles on the wing, and at a large (supercritical) angle of attack of 18 degrees, when there is a global stall of the flow from the leading edge. It was shown that the turbulent wake has a significant effect on the nature of the flow near the model surface in both cases. Local separation bubbles gradually decrease in size with a decrease in the distance between the sources of disturbances and the wing. Large-scale vortices significantly decrease in geometrical dimensions and shift towards the side edges in the event of a global stall of the flow, thereby increasing the region of the attached flow on the model surface.

Anti-Colonization Effect of Au Surfaces with Self-Assembled Molecular Monolayers Functionalized with Antimicrobial Peptides on S. epidermidis

Medical devices with an effective anti-colonization surface are important tools for combatting healthcare-associated infections. Here, we investigated the anti-colonization efficacy of antimicrobial peptides covalently attached to a gold model surface. The gold surface was modified by a self-assembled polyethylene glycol monolayer with an acetylene terminus. The peptides were covalently connected to the surface through a copper-catalyzed [3 + 2] azide-acetylene coupling (CuAAC). The anti-colonization efficacy of the surfaces varied as a function of the antimicrobial activity of the peptides, and very effective surfaces could be prepared with a 6 log unit reduction in bacterial colonization.

Prediction of sea state under tropical cyclones in the UK Met Office operational global wave model

The United Kingdom Meteorological Office (UKMO) routinely runs a global operational numerical weather prediction model. Surface winds from this model are used by a spectral wave model to forecast sea state. A brief description is given of the formulation of the wave model, and two cases of Tropical Cyclones in the Bay of Bengal are examined using the archived data generated in real time by the operational wave model. These are Tropical Cyclone 3B, 14-15 June 1996 and Tropical Cyclone 07B, 4-6 November 1996. At a resolution of 1.25° in longitude by 0.833° in latitude the numerical weather prediction model does not represent the dynamics of a tropical cyclone and the surface wind speeds are underestimated. Consequently, the extreme sea state generated by a Tropical Cyclone is not modelled. However, the wave model was able to generate a long period swell of over 3m height, which propagated away from the area of generation. Finally, work in progress to blend the operational numerical model surface winds with synthetically generated tropical cyclone surf winds, for use in the operational wave model, is outlined.

Desain Didaktis dengan Pembelajaran Matematika Realistik Pada Konsep Luas Permukaan Kubus dan Balok

The purpose of this study is to develop the didactical design concerning on the cube and cuboid surface concept. This study use Didactical Design Research measure in which it consists of three phases: (1) analysis of the didactic situation before learning that the form of design didactic hypothetical, (2) metapedadidactic analysis, and (3) retrospective analysis linked the results of analysis didactic situation hypothetical analysis and metapedadidactic analysis. This study has 96 secondary school’s students in the Cilegon city as research subjects. All datas were documented by using camera recording, interviews, and tests. The datas were analyzed qualitatively to determine the learning obstacle then researcher also compiled didactic design incorporating didactic pedagogical anticipation based on identified learning obstacles. Furthermore, the didactic design is implemented and analyzed the results of its implementation as a final product. The results obtained are a didactic concept design model surface area of cube and cuboid.

Sandbox Modeling of Transrotational Tectonics With Changeable Poles: Implications for the Yinggehai Basin

The main formation of the Yinggehai Basin has been related to the rotation of the Indochina block, resulting in large-scale strike-slip motion along the Red River Fault Zone (RRFZ). Transrotational tectonics played a key role in the evolution of the Yinggehai Basin. In this study, we present analog experiments with a preexisting basal velocity discontinuity boundary, rotation of crustal blocks concerning vertical axes, and syntectonic sedimentations to evaluate how the transrotational tectonics controls the evolutionary process of the Yinggehai Basin. Particle image velocimetry (PIV) was used to monitor the deformation of the model surface. Four successive poles of rotation have been applied to the model. The basin evolution underwent two phases. An early phase of deformation is characterized by the nucleation of the main internal faults above the velocity discontinuity boundary and segmented en echelon border fault systems. In the early phase, the internal and boundary faults mainly accommodated large-scale strike-slip displacement. During progressive extension, the main internal faults deactivated, and tectonic activity is localized along the boundary and secondary internal faults in the late phase. The boundary faults in the rotating block play a dominant role in the widening and deepening of the rift zone at an accelerating rate. The model surface morphology shows similarities to the Yinggehai Basin, which is wide in the middle and converges toward the northwest and southeast. In addition, experimental profiles have been compared with seismic profiles in the Yinggehai Basin. The model results also indicate that the rotation of the Indochina block combines with strong strike-slip motion. The similarities between modeling and nature provide support for ∼250 km sinistral displacement along the RRFZ between ∼32 and ∼21 Ma.

Experimental Investigation of the Effectiveness of Jet Impingement Cooling System on the Pressure Side of the Turbine Blade

The effectiveness of the jet impingement system on the turbine blade pressure side has been experimentally investigated. The effects of height-to-diameter ratio and air velocity on the effectiveness of jet impingement were studied. Experiments was performed under varying height-to-diameter ratios (H/D = 5, 10, 15, 20) where the distance from the nozzle to the pressure side surface ranged from 20, 40, 60 and 80 mm with a constant nozzle diameter of 4 mm. The Nusselt number is calculated to determine the cooling effect of the pressure side model surface. Experiments were also performed at varying air velocity at 6.4 m/s and 12.6 m/s. The findings revealed that there was no direct relationship between Nusselt number and H/D ratio where the optimum cooling impact at a velocity of 6.4 m/s was found to be at H/D=15, whereas at a velocity of 12.6 m/s it was found to be at H/D=5. The findings also reveal that the amount of Nusselts rises as the air velocity increases.

Thermo-fluid-mechanical numerical simulations of surface subsidence at the site of underground coal gasification

This work deals with modelling surface subsidence that aims to help industrialize Underground Coal Gasification (UCG). UCG is a long-known, but poorly industrialized method of energy extraction from coal. Risks of surface subsidence and groundwater pollution are two main hurdles that are affecting the potential industrialization of UCG. The particular challenge is the existence of groundwater because of implications to both its pollution and its influence on surface subsidence. Additionally, the coal combustion and the complex geometry of the UCG reactors impacts surface subsidence. To meet these challenges, the thermal and fluid analyses should be included in the model and surface subsidence should be modelled in three dimensions to capture the collapsed shape of the UCG reactor. Based on nature of these challenges and an earlier successful implementation, the commercial software FLAC3D by Itasca with the intrinsic thermal and fluid models is chosen to model surface subsidence.This study discovers that the inclusion of fluid analysis improves the predictions of surface subsidence when compared with measurements at the highly watered Shatsk UCG site. In turn, thermal analysis mildly influences the modelled surface subsidence. The fluid analysis shows that the flow in the upper aquifer influences surface subsidence more greatly than the flow in the lower aquifers. High temperature causes an upward flow in the lower aquifer located above the UCG reactor, but does not change the flow pattern in the upper aquifer. The fluid analysis also reveals that if the UCG reactor is filled with water, the surface subsidence does not occur.