AVO analysis for high amplitude anomalies using 2D pre-stack seismic data

Amplitude variation with offset (AVO) analysis is an 1 efficient tool for hydrocarbon detection and identification of elastic rock properties and fluid types. It has been applied in the present study using reprocessed pre-stack 2D seismic data (1992, Caulerpa) from north-west of the Bonaparte Basin, Australia. The AVO response along the 2D pre-stack seismic data in the Laminaria High NW shelf of Australia was also investigated. Three hypotheses were suggested to investigate the AVO behaviour of the amplitude anomalies in which three different factors; fluid substitution, porosity and thickness (Wedge model) were tested. The AVO models with the synthetic gathers were analysed using log information to find which of these is the controlling parameter on the AVO analysis. AVO cross plots from the real pre-stack seismic data reveal AVO class IV (showing a negative intercept decreasing with offset). This result matches our modelled result of fluid substitution for the seismic synthetics. It is concluded that fluid substitution is the controlling parameter on the AVO analysis and therefore, the high amplitude anomaly on the seabed and the target horizon 9 is the result of changing the fluid content and the lithology along the target horizons. While changing the porosity has little effect on the amplitude variation with offset within the AVO cross plot. Finally, results from the wedge models show that a small change of thickness causes a change in the amplitude; however, this change in thickness gives a different AVO characteristic and a mismatch with the AVO result of the real 2D pre-stack seismic data. Therefore, a constant thin layer with changing fluids is more likely to be the cause of the high amplitude anomalies.

Magnetohydrodynamic Flow Past a Nonlinear Stretching or Shrinking Cylinder in Nanofluid with Viscous Dissipation and Heat Generation Effect

The Tiwari-Das model is used to investigate magnetohydrodynamic stagnation point flow and heat transfer past a nonlinear stretching or shrinking cylinder in nanofluid with viscous dissipation and heat generation using. The partial differential equations, also known as governing equations, were reduced to nonlinear ordinary differential equations using similarity transformation. MATLAB with the bvp4c solver is used for numerical computing. The controlling parameter, such as nanoparticle volume fraction, magnetic, curvature, nonlinear, radiation, and heat generation parameters, as well as Eckert and Grashof numbers, influence the skin friction coefficient, heat transfer rate, velocity, and temperature profiles. The results are presented as graphs to show the influence of the variables studied. In some circumstances of stretching and shrinking cases, dual solutions can be obtained.

Time-Domain Analysis of Tamper Displacement during Dynamic Compaction Based on Automatic Control

Crater depth is a vital issue in dynamic compaction (DC) because it is a controlling parameter in DC and a characterization index of soil properties. A continuous mathematical model capturing the time-domain process of tamper displacement is presented in this paper. The model is simple and the parameters involved are easy to obtain. It was found that the accumulated crater depth increases but its increment in the crater depth decreases with multiple impacts. Three groups of large-scale DC tests with 10,000 kN∙m were conducted to evaluate the performance of the proposed model. The results showed that the proposed model captures the typical trends in the tamper displacement of single and multiple impacts. In addition, a concept of the crater depth ratio is proposed based on the proposed model, and the concept is used to evaluate the efficiency of DC and to predict the optimum tamping number of DCs.

Flow and heat transfer in a rectangular converging (diverging) channel: new formulation

In this paper, a model problem of viscous flow and heat transfer in a rectangular converging (diverging) channel has been investigated. The governing equations are presented in Cartesian Coordinates and consequently they are simplified and solved with perturbation and numerical methods. Initially, symmetrical solutions of the boundary value problem are found for the upper half of the channel. Later on, these solutions are extended to the lower half and then to the whole channel. The numerical and perturbation solutions are compared and exactly matched with each other for a small value of the parameters involved in the problem. It is also confirmed that the solutions for the converging/diverging channel are independent of the sign of m (the slope). Moreover, the skin friction coefficient and heat transfer at the upper wall are calculated and graphed against the existing parameters in different figures. It is observed that the heat transfer at walls is decreased (increased) with increasing $${c}_{1}$$ c 1 (thermal controlling parameter) for diverging (converging). It is also decreased against Pr (Prandtle number). For $${c}_{1}=0$$ c 1 = 0 , the temperature profiles may be exactly determined from the governing equations and the rate of heat transfer at the upper wall is $$\theta^{\prime } (1) = \frac{m}{{(1 + m^{2} )\tan^{ - 1} m}}$$ θ ′ ( 1 ) = m ( 1 + m 2 ) tan - 1 m . It is confirmed that the skin friction coefficient behaves linearly against Re* (modified Reynolds number) and it is increased with increasing of Re* (changed from negative to positive). Moreover, it is increased asymptotically against m and converges to a constant value i.e. zero.

Chaos in a Hybrid Food Chain Model

In this paper, chaotic and periodic dynamics in a hybrid food chain system with Holling type IV and Lotka-Volterra responses are discussed. The system is observed to be dissipative. The global stability of the equilibrium points is analyzed using Routh-Hurwitz criterion and Lyapunov direct method. Chaos phenomena is characterized by attractors and bifurcation diagram. The effect of the controlling parameter of the model is investigated theoretically and numerically.

Influence of magnetohydrodynamics and heat transfer on the reverse roll coating of a Jeffrey fluid: A theoretical study

The purpose of this article is to provide a mathematical model of magnetohydrodynamic (MHD) non-isothermal flow of an incompressible Jeffrey fluid as it goes through a minimal gap between the two counter rotating rolls. The dimensionless forms of governing equations are obtained by using appropriate dimensionless parameters. The LAT (lubrication approximation theory) is utilized to simplify the dimensionless form of governing equations. Analytical solutions for the velocity, pressure gradient, flow rate, Nusselt number and temperature distribution are presented. How the Jeffrey parameters, MHD and velocities ratio influence on the flow patterns and heat transfer rate are explored. Outcomes of some significant engineering quantities such as flow rate, power input, pressure distribution and roll separation force are obtained numerically in tabular form and some are displayed graphically. We found that the MHD parameter served as a controlling parameter for different engineering quantities like velocity, temperature, flow rate, and coating thickness. Moreover, the coating thickness on the web decreases by increasing the values of velocities ratio.

A comparison of some properties of the computer controlled nitriding process versus carburizing

A comparison is presented of the nitriding and carburizing processes. Traditional gas nitriding, despite its several advantages over carburizing, has still not achieved its due popularity. The key factor is inadequate process control. An industrial-scale computerized system, employing the nitriding potential as the fundamental controlling parameter, can produce repeatable, superior nitriding results, limiting layer brittleness and enhancing usable properties. Results obtained showed that nitriding layers match carburized layers in fatigue, while exceeding them in both impact strength and wear resistance. The superiority of the computer-controlled process over traditional nitriding is illustrated by results of wear testing. The advent of controlled nitriding makes this process a viable alternative to carburizing.

The temperature–CO₂ climate connection: an epistemological reappraisal of ice-core messages

As simply based on fundamental logic and on the concepts of cause and effect, an epistemological examination of the geochemical analyses performed on the Vostok ice cores invalidates the marked greenhouse effect on past climate usually assigned to CO2 and CH4. In agreement with the determining role assigned to Milankovitch cycles, temperature has, instead, constantly remained the long-term controlling parameter during the past 423 kyr, which, in turn, determined both CO2 and CH4 concentrations, whose variations exerted, at most, a minor feedback on temperature itself. If not refuted, the demonstration indicates that the greenhouse effect of CO2 on 20th century and today's climate remains to be documented, as already concluded from other evidence. The epistemological weakness of current simulations originates from the fact that they do not rely on any independent evidence for the influence of greenhouse gases on climate over long enough periods of time. The validity of models will, in particular, not be demonstrated as long as at least the most important features of climate changes, namely the glacial–interglacial transitions and the differing durations of interglacial periods, remain unaccounted for. Similarly, the constant 7 kyr time lag between temperature and CO2 decreases following deglaciation is another important feature that needs to be understood. Considered in this light, the current climate debate should be considered as being the latest of the great controversies that have punctuated the march of the Earth sciences, although its markedly differs from the preceding ones by its most varied social, environmental, economical and political ramifications.

A Parametric Study of Piled Raft Foundation in Clay Subjected to Concentrated Loading

The use of piled raft foundation in building and infrastructure constructions is increasingly popular because of its effectiveness in reducing overall and differential settlements. Parameters influencing the performance of the piled raft foundation need to be comprehended in order to optimize the design of the piled raft system. Most of the current available literature focused on the piled raft foundation subjected to a uniform distributed load in sandy material. This parametric study aims to provide insights into the performance of the piled raft foundations subjected to concentrated loading in clay. A series of 2D finite element analyses were performed to investigate the influencing parameters affecting the load distribution and settlement behaviour of the piled raft. The results suggested that increases in both pile length and raft thickness, as well as a decrease in pile spacing would reduce the differential settlement of the piled raft. Comparatively, raft thickness was the most significant controlling parameter affecting the differential settlement. The study also revealed the importance of placing the pile nearer to the location of concentrated load as it would yield a more uniform load distribution, and hence a lower differential settlement.

Regulating heat conduction of complex networks by distributed nodes masses

Developing efficient strategy to regulate heat conduction is a challenging problem, with potential implication in the field of thermal materials. We here focus on a potential thermal material, i.e. complex networks of nanowires and nanotubes, and propose a model where the mass of each node is assigned proportional to its degree with $$m_i\sim k_i^{\alpha }$$ m i ∼ k i α , to investigate how distributed nodes masses can impact the heat flow in a network. We find that the heat conduction of complex network can be either increased or decreased, depending on the controlling parameter $$\alpha$$ α . Especially, there is an optimal heat conduction at $$\alpha =1$$ α = 1 and it is independent of network topologies. Moreover, we find that the temperature distribution within a complex network is also strongly influenced by the controlling parameter $$\alpha$$ α . A brief theoretical analysis is provided to explain these results. These findings may open up appealing applications in the cases of demanding either increasing or decreasing heat conduction, and our approach of regulating heat conduction by distributed nodes masses may be also valuable to the challenge of controlling waste heat dissipation in highly integrated and miniaturized modern devices.