Inquisition of Electro-Magnetic Riga Plate for Laminar Flow

The probation is made to study the stagnation point flow of non-Newtonian fluid for Riga plate. Electric potential and magnetic flux density with time dependent flow is examined. Mesh for electric potential, magnetic flux, laminar flow with physics controlled fine, finer and extra finer option is also represented in details. Inquisition is solved in COMSOL Multi-physics 5.4 to obtain the results of surface magnitude, counter, table surface, magnetic flux, electric potential and coarse mesh for velocity, pressure, magnetic and electric fields. Coarse mesh of electric insulation and magnetic flux of the geometry is created with 6067, 18688 domain elements and 901, 1448 boundary elements. Tables for velocity surface, mesh domain, quadrilateral and triangular elements are also presented. Obtained results are discussed with graphs and tables in details.

Seasonal coastal upwelling in the Bali Strait: a model study

Bali Strait is part of fisheries management zone (WPP 573), where abundant fishery potential, of lemuru fish commodity. Here, physical oceanographic setting such as upwelling event plays an important role on maintaining high primary productivity and lemuru fish distribution. This study aims to describe physical process and dynamics of seasonal coastal upwelling using time-series datasets (2008 and 2014) of temperature, salinity, current velocity, surface chlorophyll-a (chl-a) from INDESO model and satellite imagery. The results showed that upwelling in the Bali Strait only during the southeast monsoon period when the south-easterly wind force surface Ekman drift of about 5.5 × 10−3 Sv flowing south-eastward (toward offshore). Upwelling event is characterized by minimum parameter of sea surface temperature (24.93 °C), and sea level anomaly (0.75 m), but maximum of surface chlorophyll-a (1.33 mg/m3). Furthermore, isotherm of 26 °C and Isohaline 33.7 psu are outcropped at sea surface in the center of upwelling zone. In contrast, during the nortwest monsoon period these isolines remain at deeper layer of about 80-90 m depth. Mean temperature-based upwelling index during peak of upwelling in August (1.19±0.19 °C). Upwelling impact on high abundance of lemuru fish (Sardinella sp.) production two month later after peak of chl-a.

Melting heat analysis in squeezed flow of nanofluids (SWCNTs + Water, SWCNTs + Gasoline oil, MWCNTs + Water, MWCNTs + Gasoline oil) with Cattaneo–Cristov heat flux

This analysis emphasizes impacts of CNTs (Carbon nanotubes) during Darcy–Forchheimer squeezed flow. Melting heat transfer process is addressed. Water and gasoline are treated as baseliquid. By transformation method non-linear system of ODEs are obtained from the flow field equations (PDEs). Further the emerged flow problem is solved via OHAM. Influences of physical involved parameters on velocity, surface friction coefficient, temperature as well as Nusselt number are expressed graphically and interpreted physically.

Investigating the Effect of Preimpact Energy Dissipation on Coefficient of Restitution regarding the Slope-Boulder Interaction

Coefficient of restitution is regarded as a dominating parameter in rockfall research. Generally, small-scale experiments were developed without considering interactions between boulder and slope. However, preimpact moving statuses are essential to evaluate rockfall behaviors. To reveal the effect of preimpact interactions on coefficient of restitution, energy dissipation considering initial velocity, surface type, and slope angle is executed based on medium-scale tests. The results show that (1) as the inclination of initial velocity, higher rebound height, and the declining normal coefficient of restitution occur, a determinable linear function could demonstrate relationships among energy dissipation and all coefficient of restitution; when initial velocity exceeds 5 m/s, the recovery ability shows and produces an increasing trend with respect to the variation of kinematic coefficient of restitution and kinetic energy coefficient of restitution. (2) As the surface material varies, slope hardness and rebound ability influence normal coefficient of restitution, and the surface roughness and rotation feature dominate tangential coefficient of restitution; considering preimpact slope and boulder interactions, four types of coefficient of restitution follow declining trend with different material sequence. (3) Slope angle affects normal coefficient of restitution, and tangential coefficient of restitution relatively descends 18% and inclines 10% when the angle ranges from 30° to 75°; regarding preimpact moving status, it differs from bounce times. The correlation between preimpact energy dissipation and four coefficients of restitution can be represented by the same decreasing linear function, when increasing the slope angle.

On-axis triplications in elastic orthorhombic media

SUMMARY Triplicated traveltime curve has three arrivals at a given distance with the bowtie shape in the traveltime-offset curve. The existence of the triplication can cause a lot of problems such as several arrivals for the same wave type, anomalous amplitudes near caustics, anomalous behaviour of rays near caustics, which leads to the structure imaging deviation and redundant signal in the inversion of the model parameters. Hence, triplication prediction becomes necessary when the medium is known. The research of the triplication in transversely isotropic medium with a vertical symmetry axis (VTI) has been well investigated and it has become clear that, apart from the point singularity case, the triplicated traveltime only occurs for S wave. On contrary to the VTI case, the triplication behaviour in the orthorhombic (ORT) medium has not been well focused due to the model complexity. In this paper, we derive the second-order coefficients of the slowness surface for two S waves in the vicinity of three symmetry axes and define the elliptic form function to examine the existence of the on-axis triplication in ORT model. The existence of the on-axis triplication is found by the sign of the defined curvature coefficients. Three ORT models are defined in the numerical examples to analyse the behaviour of the on-axis triplication. The plots of the group velocity surface in the vicinity of three symmetry axes are shown for different ORT models where different shapes: convex or the saddle-shaped (concave along one direction and convex along with another) indicates the existence of the on-axis triplication. We also show the traveltime plots (associated with the group velocity surface) to illustrate the effect of the on-axis triplication.

Flow Visualization of Footballs to Analyze the Factors Affecting their Aerodynamic Performance Using CFD

The motion of a football in air is influenced by the combination of various aerodynamic effects caused by the parameters such as velocity, surface roughness, panel orientation and shape. This paper analyzes the individual and combined effects of these parameters on the flight characteristics of various footballs using CFD Analysis. Four balls, a smooth sphere, a 32-panel conventional football, 14-panel Teamgeist and 6-panel Brazuca ball are subjected to different velocities of air flow over them, both in the laminar and turbulent regime, different surface roughness values and the influence of these parameters on the aerodynamics of the balls is evaluated by the drag force, drag coefficient and hydrodynamic boundary layer separation angle. The effect of the seam length, number of panels and panel orientation are also compared. The results of these effects are discussed later in the paper and are used to explain the knuckling effects and unpredictable trajectory of the Jabulani ball.

Approximate Analytical Periodic Solutions to the Restricted Three-Body Problem with Perturbation, Oblateness, Radiation and Varying Mass

Against the background of a restricted three-body problem consisting of a supergiant eclipsing binary system, the two primaries are composed of a pair of bright oblate stars whose mass changes with time. The zero-velocity surface and curve of the problem are numerically studied to describe the third body’s motion area, and the corresponding five libration points are obtained. Moreover, the effect of small perturbations, Coriolis and centrifugal forces, radiative pressure, and the oblateness and mass parameters of the two primaries on the third body’s dynamic behavior is discussed through the bifurcation diagram. Furthermore, the second- and third-order approximate analytical periodic solutions around the collinear solution point L3 in two-dimensional plane and three-dimensional spaces are presented by using the Lindstedt-Poincaré perturbation method.

Valuation of the Durability of the Concrete Used in the Precast Great Soviet Panel System

The durability of the concrete of the precast Great Soviet Panel system is valued through the resistance to compression, ultrasonic pulse velocity, surface methods, humidity and potential of corrosion. The evaluation is approached, essentially, through experimental and statistical methods, nevertheless, historical-logical and technical methods, such as surveys and interviews, are used in order to gather a bigger amount of information on the resistance to compression of the elements in the original project. While analyzing the results, we can conclude that, in elements in a good technical-constructive state that conform the constructions in exploitation, concrete has an average resistance. However, in elements with the presence of pathological damages, the resistance is low due to the fact that elements show chemical deterioration processes caused by water exposure, which generates the formation of soluble paste compounds, loss of mass, and decrease in mechanical resistance, among other alterations. At the same time, carbonation of concrete is triggered, which, in turn, causes the corrosion of the reinforcing steel. This corrosion leads to the cracking of concrete, delamination of steel, decrease of the concrete-steel adhesion, and other manifestations that affect the durability of concrete. Therefore, the incidence of the durability of concrete should be valued in the structural seismic behavior of constructions.

Inter-and Intra-annual Surface Velocity Variations at the Southern Grounding Line of Amery Ice Shelf from 2014 to 2018

The ice flow rate through the grounding line of the Amery Ice Shelf (AIS) is vital to understanding the mass discharge received from its three primary tributary glaciers. Previous studies have indicated a stable multiyear average surface velocity distribution in the convergence area of AIS. However, the surface velocity variations, especially short-term fluctuations, in the AIS have been relatively undocumented. This study investigated inter-annual and intra-annual surface velocity variations along the southern segment of AIS grounding line from 2014 to 2018. Using feature tracking to derive surface velocity for five consecutive austral summers and winters, it was found that AIS’s upstream end has experienced a steady ~ 5 % inter-annual increase in surface velocity. Surface velocity increases were observed in 2014/2015 (0.25 ± 0.02 m/d) and in 2017/2018 (0.21 ± 0.02 m/d) respectively. Surface velocities in winters were lower than the summers except for 2016, which had a 0.12 m/d surface velocity decrease from winter to summer. Although flowing slower than the other two glaciers, Fisher Glacier exhibited the highest inter-annual increase (8.56 ± 4.36 %) and the largest intra-annual variation (−5.41 ± 5.65 %) in surface velocity of the three studied glaciers. While the surface velocity observed in 2018 was generally close to the observed velocity in 1989, the magnitude of velocity variations observed during the 2014–2018 period is similar to the differences in velocities measured at the grounding line since 1989. This indicates continued relative stability in the surface velocities at the grounding line of these three tributary glaciers but also indicates that caution should be applied when interpreting long-term differences based on a limited number of measurements. This study demonstrated the capability of feature tracking to monitor the multidecadal changes of surface velocity.

Experimental Examination of Process Parameters During Fabrication and Machining of Powder Metallurgy Aluminum Component

The present study aims at investigating the effect of process characteristics during fabrication and machining of powder metallurgy (PM) Aluminium cylindrical components. The application of the machining process as an alternate manufacturing process to fabricate the PM Aluminium components for industrial use with desired shape and size is explored. The PM Aluminium cylindrical components were fabricated by compacting the Aluminium metal powder within the compaction dies under various values of compaction load, sintering temperature and sintering time. These PM components were then machined under different standard cutting velocity and tangential cutting velocity, surface roughness data were analyzed. After the investigation it was concluded that, higher values of compaction load, sintering time and sintering temperature leads to higher values of relative density and relative hardness of the sintered Aluminum component. Again from machining results it can be stated that, higher values of fabricating parameters have a higher significance on performance parameters.