Analytical Models to Estimate the Time Dependent Increase in Pile Capacity (Pile Set-Up)

2017 ◽  
pp. 143-156
Author(s):  
Murad Y. Abu-Farsakh ◽  
Md. Nafiul Haque
Keyword(s):  
Time Dependent ◽  
Analytical Models ◽  
Pile Capacity ◽  
Set Up

scholarly journals Active control of liquid film flows: beyond reduced-order models

2021 ◽  
Vol 104 (1) ◽  
pp. 267-287
Author(s):  
Radu Cimpeanu ◽  
Susana N. Gomes ◽  
Demetrios T. Papageorgiou
Keyword(s):  
Liquid Film ◽  
Information Transfer ◽  
Analytical Models ◽  
Feedback Controls ◽  
Reduced Order ◽  
Modelling Framework ◽  
Theoretical Approaches ◽  
Active Feedback ◽  
Feedback Strategies ◽  
Set Up

AbstractThe ability to robustly and efficiently control the dynamics of nonlinear systems lies at the heart of many current technological challenges, ranging from drug delivery systems to ensuring flight safety. Most such scenarios are too complex to tackle directly, and reduced-order modelling is used in order to create viable representations of the target systems. The simplified setting allows for the development of rigorous control theoretical approaches, but the propagation of their effects back up the hierarchy and into real-world systems remains a significant challenge. Using the canonical set-up of a liquid film falling down an inclined plane under the action of active feedback controls in the form of blowing and suction, we develop a multi-level modelling framework containing both analytical models and direct numerical simulations acting as an in silico experimental platform. Constructing strategies at the inexpensive lower levels in the hierarchy, we find that offline control transfer is not viable; however, analytically informed feedback strategies show excellent potential, even far beyond the anticipated range of applicability of the models. The detailed effects of the controls in terms of stability and treatment of nonlinearity are examined in detail in order to gain understanding of the information transfer inside the flows, which can aid transition towards other control-rich frameworks and applications.

The structure of weakly compressible grid-generated turbulence

2001 ◽  
Vol 432 ◽  
pp. 219-283 ◽  
Author(s):  
G. BRIASSULIS ◽  
J. H. AGUI ◽  
Y. ANDREOPOULOS
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Three Dimensional ◽  
High Amplitude ◽  
Time Dependent ◽  
Wide Range ◽  
Dynamical Flow ◽  
Set Up ◽  
Decay Exponent

A decaying compressible nearly homogeneous and nearly isotropic grid-generated turbulent flow has been set up in a large scale shock tube research facility. Experiments have been performed using instrumentation with spatial resolution of the order of 7 to 26 Kolmogorov viscous length scales. A variety of turbulence-generating grids provided a wide range of turbulence scales with bulk flow Mach numbers ranging from 0.3 to 0.6 and turbulent Reynolds numbers up to 700. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was also found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A possible mechanism responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid. Measurements of the time-dependent, three dimensional vorticity vectors were attempted for the first time with a 12-wire miniature probe. This also allowed estimates of dilatation, compressible dissipation and dilatational stretching to be obtained. It was found that the fluctuations of these quantities increase with increasing mean Mach number of the flow. The time-dependent signals of enstrophy, vortex stretching/tilting vector and dilatational stretching vector were found to exhibit a rather strong intermittent behaviour which is characterized by high-amplitude bursts with values up to 8 times their r.m.s. within periods of less violent and longer lived events. Several of these bursts are evident in all the signals, suggesting the existence of a dynamical flow phenomenon as a common cause.

scholarly journals MANET of an Effective Defence Scheme for Suggestion Based Trust Model

2021 ◽  
Vol 10 (5) ◽  
pp. 453-456
Author(s):  
Barath Kumar R ◽  
Stalin Alex
Keyword(s):  
Trust Model ◽  
Time Dependent ◽  
Critical Problem ◽  
Trust Degree ◽  
Course Changes ◽  
Trust Models ◽  
Grouping Method ◽  
Indirect Trust ◽  
Set Up ◽  
Difficult Issue

The immovable nature of passing on packages through multi -bounce middle hubs is a critical problem in the versatile impromptu organizations (MANETs). The disseminated versatile hubs set up associations with structure the MANET, which may incorporate childish and getting into mischief hubs. Suggestion based trust the board is proposed in the creating as a system to evaluate through the acting up hubs while looking for a bundle conveyance course. Nonetheless, building a trust model that embraces suggestions by different hubs in the organization is a difficult issue because of the danger of deceptive proposals like reviling, voting form stuffing, and conspiracy. we examines the issues identified with assaults presented by getting rowdy hubs while proliferating suggestions in the current trust models. We propose a suggestion based trust model with a safeguard plot, which uses grouping method to progressively sift through assaults identified with exploitative proposals between certain time dependent on number of collaborations, similarity of data and closeness between the hubs. We evaluate the trust degree as two cases like direct and indirect trust values between neighboring nodes from source. To form a clustering routing network from similar trust values from S to D.The model is experimentally tried under a few portable and detached geographies in which hubs experience changes in their local prompting regular course changes. The observational investigation shows heartiness and exactness of the trust model in a dynamic MANET climate.

One-dimensional consolidation of multilayered aquifer systems with viscoelastic properties induced by time-dependent groundwater drawdown

2021 ◽  
pp. qjegh2021-073
Author(s):  
Weitao Yang ◽  
Jin Xu
Keyword(s):  
Viscoelastic Properties ◽  
Numerical Solutions ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Time Dependent ◽  
Analytical Models ◽  
Consolidation Process ◽  
One Dimensional ◽  
Groundwater Drawdown ◽  
Aquifer Systems

Most analytical and semi-analytical models for pumping-induced land subsidence invoke the simplifying assumptions regarding characteristics of geomaterials, as well as the pattern of drawdown response to pumping. This paper presents an analytical solution for one-dimensional consolidation of the multilayered soil due to groundwater drawdown, in which viscoelastic property and time-dependent drawdown are taken into account. The presented solution is developed by using the boundary transformation techniques. The validity of the proposed solution is verified by comparing with a degenerated case for a single layer, as well as with the numerical solutions and experimental results for a two-layer system. The difference between the average consolidation degree Up defined by hydraulic head and that Us defined by total settlement is discussed. The detailed parametric studies are conducted to reveal the effects of viscoelastic properties and drawdown patterns on the consolidation process. It is revealed that while the effect of different drawdown response patterns is significant during the early-intermediate stages of consolidation, the viscoelastic properties may have a more dominant influence on long-term consolidation behavior, depending on the values of the material parameters, which are reflected in both the deformation process of soil layers and the dissipation of excess pore-water pressure.

Dynamic Fields and Response Properties

2020 ◽  
pp. 473-554
Author(s):  
Jochen Autschbach
Keyword(s):  
Absorption Coefficient ◽  
Linear Response ◽  
Optical Rotation ◽  
Polarized Light ◽  
Linear Response Theory ◽  
Time Dependent ◽  
Electronic Transitions ◽  
Orbital Theory ◽  
Response Properties ◽  
Set Up

It is shown how electronic transitions can be induced by the interaction with an electromagnetic wave of a suitable frequency. The rate of a transition between two electronic states induced by a time-dependent field is derived. The transition rate expression is used to calculate the absorption coefficient due to electronic transitions. The differential absorption coefficient for left and right circular polarized light is specific to chiral molecules and has different signs for a pair of enantiomers. The discussion then shifts to general functions describing the response of an atom or molecule to an external. The ideas developed thus far are then applied to the dynamic polarizability, molecular linear response functions in general, and the optical rotation. Linear response theory is set up within time-dependent molecular orbital theory. The Chapter concludes with a discussion of non-linear response properties and two-photon absorption.

Moments of certain stochastic integrals occurring in mathematical physics

1992 ◽  
Vol 120 (3-4) ◽  
pp. 267-282 ◽  
Author(s):  
Lieven Smits
Keyword(s):  
Brownian Motion ◽  
Vector Field ◽  
Mathematical Physics ◽  
Time Dependent ◽  
Regularity Conditions ◽  
Stochastic Integrals ◽  
Cauchy Problems ◽  
Dependent Vector ◽  
Set Up

SynopsisWe give an expression for the n-th moment of certain Itô integrals. The integrands considered are nonanticipating functionals of the form s↦a(s, Xs), where a is a measurable time-dependent vector field in space satisfying mild regularity conditions, and Xs is standard translated Brownian motion. The expressions are similar to the Dyson-Phillips terms for magnetic Schrödinger semigroups.We use these expressions to establish properties of the solutions of certain Cauchy problems and we relate our results to the framework of generalised Dyson expansions as set up by Johnson and Lapidus.

scholarly journals Mathematical modeling of groundwater contamination with varying velocity field

2017 ◽  
Vol 65 (2) ◽  
pp. 192-204 ◽  
Author(s):  
Pintu Das ◽  
Sultana Begam ◽  
Mritunjay Kumar Singh
Keyword(s):  
Groundwater Contamination ◽  
Analytical Solutions ◽  
Diffusion Coefficients ◽  
Numerical Solutions ◽  
Finite Difference Methods ◽  
Time Dependent ◽  
Analytical Models ◽  
Retardation Factor ◽  
Hydrodynamic Dispersion ◽  
The Impact

Abstract In this study, analytical models for predicting groundwater contamination in isotropic and homogeneous porous formations are derived. The impact of dispersion and diffusion coefficients is included in the solution of the advection-dispersion equation (ADE), subjected to transient (time-dependent) boundary conditions at the origin. A retardation factor and zero-order production terms are included in the ADE. Analytical solutions are obtained using the Laplace Integral Transform Technique (LITT) and the concept of linear isotherm. For illustration, analytical solutions for linearly space- and time-dependent hydrodynamic dispersion coefficients along with molecular diffusion coefficients are presented. Analytical solutions are explored for the Peclet number. Numerical solutions are obtained by explicit finite difference methods and are compared with analytical solutions. Numerical results are analysed for different types of geological porous formations i.e., aquifer and aquitard. The accuracy of results is evaluated by the root mean square error (RMSE).

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