An Investigation on the Excitation of Yaw Parametric Resonance of a Tension Leg Platform

2012 ◽  
Author(s):  
Roberto Edward Cruz ◽  
Marcelo A. S. Neves ◽  
Luis Alberto Rivera ◽  
Paulo T. T. Esperança
Keyword(s):  
Mathematical Model ◽  
Time Series ◽  
Numerical Simulations ◽  
Parametric Resonance ◽  
Hydrodynamic Interactions ◽  
Tension Leg Platform ◽  
Model Experiments ◽  
Close Proximity ◽  
Sway Motion ◽  
Adequate Agreement

The paper summarizes some aspects of a series of model experiments conducted with a Tension Leg Platform (in fact a Tension Leg Wellhead Platform) in close proximity with a FPSO emphasizing the types of coupled motions taking place. It is observed that as the yaw motion develops increasing amplitudes the sway motion is reduced, pointing out to an interesting exchange of energy between the sway and yaw modes. This should be recognized as a revealing aspect of strongly non-linear coupled parametric resonant motions. A mathematical model is proposed to describe the main aspects of the two-body moored system and hydrodynamic interactions. In principle a 12-DOF model is contemplated. Numerical simulations are compared to the time series obtained from the experiments showing adequate agreement. However, in this paper the essential coupling of sway and yaw is distinguished in order to typify the Mathieu-type instability as being the main mechanism behind the onset of large yaw motions of the TLP unit.

scholarly journals Volterra–Lyapunov Stability Analysis of the Solutions of Babesiosis Disease Model

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1272
Author(s):  
Fengsheng Chien ◽  
Stanford Shateyi
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Global Stability ◽  
Numerical Simulations ◽  
Lyapunov Stability ◽  
Disease Model ◽  
Transmission Dynamics ◽  
Global Stability Analysis ◽  
Lyapunov Stability Analysis ◽  
Disease Free

This paper studies the global stability analysis of a mathematical model on Babesiosis transmission dynamics on bovines and ticks populations as proposed by Dang et al. First, the global stability analysis of disease-free equilibrium (DFE) is presented. Furthermore, using the properties of Volterra–Lyapunov matrices, we show that it is possible to prove the global stability of the endemic equilibrium. The property of symmetry in the structure of Volterra–Lyapunov matrices plays an important role in achieving this goal. Furthermore, numerical simulations are used to verify the result presented.

Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality

2013 ◽  
Vol 760-762 ◽  
pp. 2263-2266
Author(s):  
Kang Yong ◽  
Wei Chen
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Yield Strength ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Significant Influence ◽  
External Pressure ◽  
Pipe Diameter ◽  
Axial Loads ◽  
The Stability

Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

Systems Actuated by Shape Memory Alloys: Identification and Modeling

2021 ◽  
Vol 1 (2) ◽  
pp. 12-20
Author(s):  
Najmeh Keshtkar ◽  
Johannes Mersch ◽  
Konrad Katzer ◽  
Felix Lohse ◽  
Lars Natkowski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Numerical Simulations ◽  
Shape Memory ◽  
Transfer Equation ◽  
Mechanical Parameters ◽  
Heat Transfer Equation ◽  
The Mathematical Model

This paper presents the identification of thermal and mechanical parameters of shape memory alloys by using the heat transfer equation and a constitutive model. The identified parameters are then used to describe the mathematical model of a fiber-elastomer composite embedded with shape memory alloys. To verify the validity of the obtained equations, numerical simulations of the SMA temperature and composite bending are carried out and compared with the experimental results.

scholarly journals A Dynamic Model of PI3K/AKT Pathways in Acute Myeloid Leukemia

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yudi Ari Adi ◽  
Fajar Adi-Kusumo ◽  
Lina Aryati ◽  
Mardiah S. Hardianti
Keyword(s):  
Mathematical Model ◽  
Acute Myeloid Leukemia ◽  
Numerical Simulations ◽  
Signaling Pathways ◽  
Myeloid Leukemia ◽  
Akt Signaling ◽  
Dimensional System ◽  
First Order ◽  
Immature Myeloid Cells ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a malignant hematopoietic disorder characterized by uncontrolled proliferation of immature myeloid cells. In the AML cases, the phosphoinositide 3-kinases (PI3K)/AKT signaling pathways are frequently activated and strongly contribute to proliferation and survival of these cells. In this paper, a mathematical model of the PI3K/AKT signaling pathways in AML is constructed to study the dynamics of the proteins in these pathways. The model is a 5-dimensional system of the first-order ODE which describes the interaction of the proteins in AML. The interactions between those components are assumed to follow biochemical reactions, which are modelled by Hill’s equation. From the numerical simulations, there are three potential components targets in PI3K/AKT pathways to therapy in the treatment of AML patient.

scholarly journals Development of a Mathematical Model for Tracking Movement of a Human Limb in Three-Dimensional Space Using MEMS Sensors

2021 ◽  
Vol 11 (3) ◽  
pp. 74-82
Author(s):  
N.I. Levonovich
Keyword(s):  
Mathematical Model ◽  
Dimensional Space ◽  
Practical Importance ◽  
Three Dimensional ◽  
Suitable Model ◽  
Mems Sensors ◽  
Model Experiments ◽  
Human Limb ◽  
Tracking Movement ◽  
Three Dimensional Space

This article discusses the development of a mathematical model for a device capable of tracking the movements of a human limb based on the readings of microelectromechanical sensors. For developing and selecting the most suitable model, experiments were conducted based on publicly available components. The result obtained is of practical importance since it can be used to create a device.

scholarly journals A mathematical model of infectious disease transmission

2020 ◽  
Vol 34 ◽  
pp. 02002
Author(s):  
Aurelia Florea ◽  
Cristian Lăzureanu
Keyword(s):  
Infectious Disease ◽  
Mathematical Model ◽  
Nonlinear System ◽  
Numerical Simulations ◽  
Disease Transmission ◽  
Three Dimensional ◽  
Type System ◽  
Epidemic Disease ◽  
Infectious Disease Transmission ◽  
The Stability

In this paper we consider a three-dimensional nonlinear system which models the dynamics of a population during an epidemic disease. The considered model is a SIS-type system in which a recovered individual automatically becomes a susceptible one. We take into account the births and deaths, and we also consider that susceptible individuals are divided into two groups: non-vaccinated and vaccinated. In addition, we assume a medical scenario in which vaccinated people take a special measure to quarantine their newborns. We study the stability of the considered system. Numerical simulations point out the behavior of the considered population.

Eddy Current Flow Meter Performance in Liquid Metal Flows Inclined to the Sensor Axis

2021 ◽  
Author(s):  
Nico Krauter ◽  
Vladimir Galindo ◽  
Thomas Wondrak ◽  
Sven Eckert ◽  
Gunter Gerbeth
Keyword(s):  
Liquid Metal ◽  
Numerical Simulations ◽  
Eddy Current ◽  
Current Flow ◽  
Fast Reactors ◽  
Flow Meter ◽  
Flow Angle ◽  
Model Experiments ◽  
Inductive Sensor ◽  
Pipe Flows

Abstract The Eddy Current Flow Meter is a reliable and robust inductive sensor for the measurement of flowrates in liquid metal flows. This kind of sensor is usually being used in pipe flows where the flow is mostly parallel to the sensor axis. When this sensor is used as part of the safety instrumentation above the subassemblies in liquid metal cooled fast reactors, the flow angle may change rapidly according to the conditions within the reactor. In this paper we investigate the performance of the Eddy Current Flow Meter in flows inclined to the sensor axis by numerical simulations as well as model experiments. We demonstrate that the Eddy Current Flow Meter yields reliable results for flow angles up to 30° while the sensitivity of the sensor is significantly reduced for larger angles.

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