scholarly journals Three-Dimensional Dynamic Modelling and Validation for Vibration of a Beam-Cable System

2021 ◽  
Vol 27 (1) ◽  
pp. 87-116
Author(s):  
Mohammad Hadi Jalali ◽  
Geoff Rideout
Keyword(s):  
Three Dimensional ◽  
Dynamic Modelling ◽  
Cable System

Novel CMR techniques for advanced surgical planning

2018 ◽  
pp. 502-508
Author(s):  
Mark A Fogel
Keyword(s):  
Magnetic Resonance ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Surgical Care ◽  
Velocity Mapping ◽  
Three Dimensional Printing ◽  
Improved Outcomes ◽  
Medical Advances ◽  
Dimensional Printing

Medical and surgical care for the patient with congenital heart disease (CHD) has advanced greatly over the past 40 years; along with improved surgical and catheter-based techniques, intensive unit care, and overall medical advances, improved outcomes have accrued across a whole host of cardiac defects. This is owed, in no small part, to advances in imaging and cardiovascular magnetic resonance (CMR) which has played an important and growing role in this evolution. Novel CMR techniques 25 years ago, such as gadolinium-based imaging and two-dimensional velocity mapping, are now commonplace. At the cutting edge of novel CMR techniques, in the current era, are computational fluid dynamic modelling, three-dimensional printing, four-dimensional flow imaging, and X-ray magnetic resonance/interventional CMR, which will be the focus of this chapter. The hope is that one day these techniques will be the commonplace ones, aiding in the care of a broad spectrum of CHD.

Design, dynamic modelling and control of a bio-inspired helical swimming microrobot with three-dimensional manoeuvring

2016 ◽  
Vol 39 (7) ◽  
pp. 1037-1046 ◽  
Author(s):  
Hossein Nourmohammadi ◽  
Jafar Keighobadi ◽  
Mohsen Bahrami
Keyword(s):  
Feedback Linearization ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Linearization Method ◽  
The Body ◽  
Motion Trajectories ◽  
Mems Technology ◽  
Propulsion Force ◽  
Resistive Force Theory

Biomedical applications of swimming microrobots comprising of drug delivery, microsurgery and disease monitoring make the research more interesting in MEMS technology. In this paper, inspired by the flagellar motion of microorganisms like bacteria and also considering the recent attempts in one/two-dimensional modelling of swimming microrobots, a three degrees-of-freedom swimming microrobot is developed. In the proposed design, the body of the swimming microrobot is driven by multiple prokaryotic flagella which produce a propulsion force through rotating in the fluid media. The presented swimming microrobot has the capability of doing three-dimensional manoeuvres and moving along three-dimensional reference paths. In this paper, following dynamical modelling of the microrobot motion, a suitable controller is designed for path tracking purposes. Based on the resistive-force theory, the generated propulsion force by the flagella is modelled. The feedback linearization method is applied for perfect tracking control of the swimming microrobot on the desired motion trajectories. It is seen that, by the use of three flagella, the microrobot is able to perform three-dimensional manoeuvres. From the simulation results, the tracking performance of the designed control system is perfectly guaranteed which enables the microrobot to perform the desired three-dimensional manoeuvres and follow the desired trajectory.

A model for the analysis of rapid landslide motion across three-dimensional terrain

2004 ◽  
Vol 41 (6) ◽  
pp. 1084-1097 ◽  
Author(s):  
Scott McDougall ◽  
Oldrich Hungr
Keyword(s):  
Debris Flows ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Rock Avalanche ◽  
Stress Distributions ◽  
Flume Experiments ◽  
Mesh Distortion ◽  
Flow Slides ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

A new numerical model for the dynamic analysis of rapid flow slides, debris flows, and avalanches has been developed. The model is an extension of an earlier algorithm and is implemented using a numerical method adapted from smoothed particle hydrodynamics. Its features include (i) the ability to simulate flow across complex three-dimensional terrain; (ii) the ability to allow nonhydrostatic and anisotropic internal stress distributions, coupled with strain changes through frictional relationships; (iii) the ability to simulate material entrainment; (iv) a choice of different rheological kernels, including frictional, plastic, viscous, Bingham, and Voellmy; (v) a meshless solution, which eliminates problems with mesh distortion during long displacements; and (vi) highly efficient and simple operation. The model has been tested by analysing a series of laboratory flume experiments with granular materials, both on straight and curved paths. The model is capable of accurately predicting the margins of various curving flows using a single set of input parameters. A preliminary analysis of a real rock avalanche case history is also included.Key words: landslides, debris flows, rock avalanches, runout analysis, dynamic modelling, numerical methods.

Viscoelastic Characterization of Woven Dacron for Aortic Grafts by Using Direction-Dependent Quasi-Linear Viscoelasticity

2018 ◽  
Author(s):  
Eleonora Tubaldi ◽  
Giovanni Ferrari ◽  
Prabakaran Balasubramanian ◽  
Ivan Breslavskyi ◽  
Marco Amabili
Keyword(s):  
Dynamic Modulus ◽  
Static Loading ◽  
Linear Viscoelasticity ◽  
Loss Factor ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Experimental Characterization ◽  
Infinite Time ◽  
Aortic Prosthesis

In case of direction-dependent viscoelasticity, a simplified formulation of the three-dimensional quasi-linear viscoelasticity has been obtained manipulating the original Fung equation. The experimental characterization of the static hyperelastic behaviour, the relaxation, the dynamic modulus and the loss factor of woven Dacron from a commercial aortic prosthesis has been performed. An 11 % difference of the reduced relaxation (after infinite time) between axial and circumferential directions has been observed for the woven Dacron. A very large increase in stiffness is obtained in case of harmonic loading with respect to the static loading. These findings are particularly relevant for dynamic modelling of currently used aortic grafts.

Dynamic Modelling of Horizontal Shafts With Annular Surface Contact and Friction: Application to Oilwell Drilling

2014 ◽  
Author(s):  
Md. Mejbahul Sarker ◽  
D. Geoff Rideout ◽  
Stephen D. Butt
Keyword(s):  
Three Dimensional ◽  
Dynamic Modelling ◽  
Lateral Vibration ◽  
Horizontal Section ◽  
Stick Slip ◽  
Rock Interaction ◽  
Bottom Hole ◽  
Proposed Model ◽  
Bottom Hole Assembly ◽  
Friction Dynamics

Lateral whirl vibrations in long sections of horizontal oilwell drillstrings, which are essentially enclosed shafts lying on the low side of the wellbore, are potentially destructive to the bit, pipes and downhole tools. Forward or backward whirl can lead to impact with the borehole, and stick slip and bit bounce can cause tool joint failure, twist-off, and bit damage. A complete deviated drillstring has been modelled by having decoupled axial and torsional segments for the vertical and curved portions, and nonlinear three-dimensional multibody segments with lateral vibration in the final horizontal section ending at the bit. The model can predict how axial and torsional bit-rock reactions are propagated to the surface, and the role that lateral vibration near the bit plays in exciting those vibrations and stressing components in the bottom-hole-assembly. The proposed model includes the mutual dependence of these vibrations, which arises due to bit-rock interaction and friction dynamics between the drillstring and wellbore wall.

Dynamic Modelling of Blades Based on a Novel Curved Thin Walled Beam Theory

2018 ◽  
Author(s):  
Juan C. Jauregui ◽  
Diego Cardenas ◽  
Hugo Elizalde ◽  
Oliver Probst
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Beam Theory ◽  
General Description ◽  
B Splines ◽  
Out Of Plane ◽  
Thin Walled ◽  
Aided Design

There are several Thin-Walled Beam models for straight beams, but few TWB models consider beams with arbitrary curvatures. Although, a curved beam can be modelled using finite elements, the number of degrees of freedom is too large and a nonlinear dynamic solution is very cumbersome, if not impossible. In this work, a general description of arbitrary three-dimensional curves, based on the Frenet-Serret field frame, is applied to determine the dynamic stresses in wing turbines blades. The dynamic model is developed using the Isogeometric Analysis (IGA) and the in plane and out-of-plane curvature’s gradients are found in an Euler-type formulation, allowing the treatment of cases with highly-curved geometry. An Isogeometrical (IGA) formulation relies on a linear combination of Non-Uniform Rational B-Splines (NURBS) to represent not just the model’s geometry, a standard practice in most Computer-Aided Design (CAD) platforms, but also the unknown solution field of each sought variable. For the unified model hitherto described, these variables are represented by a NURBS curve.

scholarly journals Forecasting the behaviour of complex landslides with a spatially distributed hydrological model

2005 ◽  
Vol 5 (1) ◽  
pp. 71-85 ◽  
Author(s):  
J.-P. Malet ◽  
Th. W. J. van Asch ◽  
R. van Beek ◽  
O. Maquaire
Keyword(s):  
Hydrological Model ◽  
Spatial Information ◽  
Environmental Changes ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Primary Objective ◽  
Distributed Model ◽  
Saturated Model ◽  
Distributed Hydrological Model ◽  
Spatially Distributed

Abstract. The relationships between rainfall, hydrology and landslide movement are often difficult to establish. In this context, ground-water flow analyses and dynamic modelling can help to clarify these complex relations, simulate the landslide hydrological behaviour in real or hypothetical situations, and help to forecast future scenarios based on environmental change. The primary objective of this study is to investigate the possibility of including more temporal and spatial information in landslide hydrology forecasting, by using a physically based spatially distributed model. Results of the hydrological and geomorphological investigation of the Super-Sauze earthflow, one of the persistently active landslide occurring in clay-rich material of the French Alps, are presented. Field surveys, continuous monitoring and interpretation of the data have shown that, in such material, the groundwater level fluctuates on a seasonal time scale, with a strong influence of the unsaturated zone. Therefore a coupled unsaturated/saturated model, incorporating Darcian saturated flow, fissure flow and meltwater flow is needed to adequately represent the landslide hydrology. The conceptual model is implemented in a 2.5-D spatially distributed hydrological model. The model is calibrated and validated on a multi-parameters database acquired on the site since 1997. The complex time-dependent and three-dimensional groundwater regime is well described, in both the short- and long-term. The hydrological model is used to forecast the future hydrological behaviour of the earthflow in response to potential environmental changes.

scholarly journals Computational Fluid Dynamic Modelling and Optimisation of Wastewater Treatment Plant Bioreactor Mixer

2018 ◽  
Author(s):  
Andrew Elshaw ◽  
N. M. S. Hassan ◽  
M. M. K. Khan
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Suspended Solids ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Treatment Plant ◽  
Dynamic Modelling ◽  
Specific Power ◽  
Physical Data ◽  
Anoxic Zones

This study aims to determine the optimal configuration (position and operation duration) for wall mounted mechanical mixers based on the comparison of three-dimensional computational fluid dynamics (CFD) modelling results and physical data collected from the treatment plant. A three-dimensional model of anoxic zone 1, 2 and 3 of Northern Wastewater Treatment Plant (WWTP) located at Cairns Regional Council, Cairns, Queensland, Australia was developed and validated. The model was used to simulate the flow pattern of the WWTP and the simulation results are in good agreement with the physical data varying between 0% to 15% in key locations. The anoxic zones were subject to velocities less than the desired 0.3 metres per second however results for suspended solids concentration indicate that good mixing is being achieved. Results for suspended solids concentrations suggest that the anoxic zones are towards the upper limits recommended by literature for specific power dissipation. The duration for operation of mechanical mixers was investigated and identified that the duration could be reduced from 900 seconds down to 150 seconds. Alternative mixer positioning was also investigated and identified positioning which would increase the average flow velocity with decreased duration (150 seconds). The study identified that Council may achieve savings of $24,000 per year through optimisation of the mechanical mixers.

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