scholarly journals An estimate for the anisotropic maximum curvature in the planar case

2021 ◽  
Author(s):  
Gloria Paoli
Keyword(s):  
Planar Case ◽  
Maximum Curvature

scholarly journals Three-Dimensional Analysis of the In Vivo Motion of Implantable Cardioverter Defibrillator Leads

2021 ◽  
Author(s):  
Tamas Szili-Torok ◽  
Jens Rump ◽  
Torsten Luther ◽  
Sing-Chien Yap
Keyword(s):  
Three Dimensional ◽  
Second Phase ◽  
Two Phase ◽  
Maximum Curvature ◽  
Phase Study ◽  
Absolute Curvature ◽  
Icd Leads ◽  
Lead Testing ◽  
Design And Testing

Abstract Better understanding of the lead curvature, movement and their spatial distribution may be beneficial in developing lead testing methods, guiding implantations and improving life expectancy of implanted leads. Objective The aim of this two-phase study was to develop and test a novel biplane cine-fluoroscopy-based method to evaluate input parameters for bending stress in leads based on their in vivo 3D motion using precisely determined spatial distributions of lead curvatures. Potential tensile, compressive or torque forces were not subjects of this study. Methods A method to measure lead curvature and curvature evolution was initially tested in a phantom study. In the second phase using this model 51 patients with implanted ICD leads were included. A biplane cine-fluoroscopy recording of the intracardiac region of the lead was performed. The lead centerline and its motion were reconstructed in 3D and used to define lead curvature and curvature changes. The maximum absolute curvature Cmax during a cardiac cycle, the maximum curvature amplitude Camp and the maximum curvature Cmax@amp at the location of Camp were calculated. These parameters can be used to characterize fatigue stress in a lead under cyclical bending. Results The medians of Camp and Cmax@amp were 0.18 cm−1 and 0.42 cm−1, respectively. The median location of Cmax was in the atrium whereas the median location of Camp occurred close to where the transit through the tricuspid valve can be assumed. Increased curvatures were found for higher slack grades. Conclusion Our results suggest that reconstruction of 3D ICD lead motion is feasible using biplane cine-fluoroscopy. Lead curvatures can be computed with high accuracy and the results can be implemented to improve lead design and testing.

scholarly journals Verification Studies for the Noh Problem Using Nonideal Equations of State and Finite Strength Shocks

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Sarah C. Burnett ◽  
Kevin G. Honnell ◽  
Scott D. Ramsey ◽  
Robert L. Singleton
Keyword(s):  
Equations Of State ◽  
National Laboratory ◽  
Jump Conditions ◽  
Self Similarity ◽  
Planar Case ◽  
Los Alamos National Laboratory ◽  
Flow Equations ◽  
Arbitrary Strength ◽  
Verification Test ◽  
Gamma Law

The Noh verification test problem is extended beyond the commonly studied ideal gamma-law gas to more realistic equations of state (EOSs) including the stiff gas, the Noble-Abel gas, and the Carnahan–Starling EOS for hard-sphere fluids. Self-similarity methods are used to solve the Euler compressible flow equations, which, in combination with the Rankine–Hugoniot jump conditions, provide a tractable general solution. This solution can be applied to fluids with EOSs that meet criterion such as it being a convex function and having a corresponding bulk modulus. For the planar case, the solution can be applied to shocks of arbitrary strength, but for the cylindrical and spherical geometries, it is required that the analysis be restricted to strong shocks. The exact solutions are used to perform a variety of quantitative code verification studies of the Los Alamos National Laboratory Lagrangian hydrocode free Lagrangian (FLAG).

Lateral Equilibrium Position Analysis Program With Applications to Electric Submersible Pumps

2017 ◽  
Author(s):  
Clay S. Norrbin ◽  
Dara W. Childs
Keyword(s):  
Equilibrium Position ◽  
Static Equilibrium ◽  
Analysis Program ◽  
Eccentricity Ratio ◽  
Vertical Orientation ◽  
Maximum Curvature ◽  
First Finding ◽  
Static Eccentricity ◽  
Lateral Equilibrium ◽  
Vertical Case

The long length of sub-sea Electric Submersible Pumps (ESPs) requires a large amount of annular seals. Loading caused by gravity and housing curvature changes the Static Equilibrium Position (SEP) of the rotor in these seals. This analysis predicts the SEP due to gravity and/or well curvature loading. The analysis also interfaces displays the rotordynamics around the SEP. A static and rotordynamic analysis is presented for a previously studied ESP model. This study differs by first finding the SEP and then performing a rotordynamic analysis about the SEP. Predictions are shown in a horizontal and a vertical orientation. In these two configurations, viscosities and clearances are varied through 4 cases: 1X 1cP, 3X 1cP, 1X 30cP, and 3X 30cP. In a horizontal, straight-housing position, the model includes gravity and buoyancy on the shaft. At 1cP-1X and 1cP-3X, the horizontal statics show a moderate eccentricity ratio for the shaft with respect to the housing. With 30cP-1X, the predicted static eccentricity ratio is low at 0.08. With 30cP-3X, the predicted eccentricity ratio increases to 0.33. Predictions for a vertical case of the same model are also presented. The curvature of the housing is varied in the Y-Z plane until rub or close-to-wall rub is expected. The curvature needed for a rub with a 1X 1cP fluid is 7.5 degrees of curvature. Curvature has little impact on stability. With both 1X 30cP and 3X 30cP, the maximum curvature for a static rub are over 25 degrees of curvature. Both 1X 30cP and 3X 30cP remain unstable with increasing curvature.

scholarly journals Invertible harmonic and harmonic quasiconformal mappings

Filomat ◽  
2015 ◽  
Vol 29 (9) ◽  
pp. 1953-1967
Author(s):  
Miodrag Mateljevic
Keyword(s):  
Classical Result ◽  
Quasiconformal Mappings ◽  
Lipschitz Property ◽  
Planar Case ◽  
New Approach

Recently G. Alessandrini - V. Nesi and Kalaj generalized a classical result of H. Kneser (RKCTheorem). Using a new approach we get some new results related to RKC-Theorem and harmonic quasiconformal (HQC) mappings. We also review some results concerning bi-Lipschitz property for HQC-mappings between Lyapunov domains and related results in planar case using some novelty.

scholarly journals The lower bound for the modulus of the derivatives and Jacobian of harmonic injective mappings

Filomat ◽  
2015 ◽  
Vol 29 (2) ◽  
pp. 221-244 ◽  
Author(s):  
Miodrag Mateljevic
Keyword(s):  
Lower Bound ◽  
Unit Ball ◽  
Convex Domain ◽  
Lipschitz Property ◽  
Planar Case

We give the lower bound for the modulus of the radial derivatives and Jacobian of harmonic injective mappings from the unit ball onto convex domain in plane and space. As an application we show co-Lipschitz property of some classes of qch mappings. We also review related results in planar case using some novelty.

Coupling between shear and bending in the analysis of beam problems: Planar case

2018 ◽  
Vol 419 ◽  
pp. 510-525 ◽  
Author(s):  
Ahmed A. Shabana ◽  
Mohil Patel
Keyword(s):  
Planar Case

Cardiac Pulsatility– and Respiratory-Induced Deformations of the Renal Arteries and Snorkel Stents After Snorkel Endovascular Aneurysm Sealing

2019 ◽  
Vol 26 (4) ◽  
pp. 556-564
Author(s):  
Christopher P. Cheng ◽  
Ga-Young Suh ◽  
John J. Kim ◽  
Andrew Holden
Keyword(s):  
Renal Artery ◽  
Endovascular Aneurysm Repair ◽  
Renal Arteries ◽  
Aortic Aneurysms ◽  
Left Renal Artery ◽  
3 Dimensional ◽  
Maximum Curvature ◽  
Mechanical Durability ◽  
The Right ◽  
Aneurysm Repair

Purpose: To quantify deformations of renal arteries and snorkel stents after snorkel endovascular aneurysm sealing (Sn-EVAS) resulting from cardiac pulsatility and respiration and compare these deformations to patients with untreated abdominal aortic aneurysms (AAA) and snorkel endovascular aneurysm repair (Sn-EVAR). Materials and Methods: Ten Sn-EVAS patients (mean age 75±6 years; 8 men) were scanned with cardiac-gated, respiration-resolved computed tomography angiography. From 3-dimensional geometric models, changes in renal artery and stent angulation and curvature due to cardiac pulsatility and respiration were quantified. Respiration-induced motions were compared with those of 16 previously reported untreated AAA patients and 11 Sn-EVAR patients. Results: Renal artery bending at the stent end was greater for respiratory vs cardiac influences (6°±7° vs −1°±2°, p<0.025). Respiration caused a 3-fold greater deformation on the left renal artery as compared with the right side. Maximum curvature change was higher for respiratory vs cardiac influences (0.49±0.29 vs 0.24±0.17 cm−1, p<0.025), and snorkel renal stents experienced similar maximum curvature change due to cardiac pulsatility and respiration (0.14±0.10 vs 0.19±0.09 cm−1, p=0.142). When comparing the 3 patient cohorts for respiratory-induced deformation, there was significant renal branch angulation in untreated AAAs, but not in Sn-EVAR or Sn-EVAS, and there was significant bending at the stent end in Sn-EVAR and Sn-EVAS. Maximum curvature change due to respiration was ~10-fold greater in Sn-EVAR and Sn-EVAS compared to untreated AAAs. Conclusion: The findings suggest that cardiac and respiratory influences may challenge the mechanical durability of snorkel stents of Sn-EVAS; similarly, however, respiration may be the primary culprit for tissue irritation, increasing the risk for stent-end thrombosis, especially in the left renal artery. The bending stiffness of snorkel stents in both the Sn-EVAR and Sn-EVAS cohorts damped renal branch angulation while it intensified bending of the artery distal to the snorkel stent. Understanding these device-to-artery interactions is critical as they may affect mechanical durability of branch stents and quality and durability of treatment.

scholarly journals The asymptotically linear Hénon problem

2020 ◽  
pp. 2050042
Author(s):  
Anna Lisa Amadori
Keyword(s):  
Boundary Conditions ◽  
Morse Index ◽  
Dirichlet Boundary ◽  
Dirichlet Boundary Conditions ◽  
Radial Solutions ◽  
Asymptotically Linear ◽  
Planar Case ◽  
Asymptotic Profile ◽  
Least Energy Solutions ◽  
Least Energy

In this paper, we consider the Hénon problem in the ball with Dirichlet boundary conditions. We study the asymptotic profile of radial solutions and then deduce the exact computation of their Morse index when the exponent [Formula: see text] is close to [Formula: see text]. Next we focus on the planar case and describe the asymptotic profile of some solutions which minimize the energy among functions which are invariant for reflection and rotations of a given angle [Formula: see text]. By considerations based on the Morse index we see that, depending on the values of [Formula: see text] and [Formula: see text], such least energy solutions can be radial, or nonradial and different one from another.

scholarly journals Optimization of Interplanetary Trajectories Using the Colliding Bodies Optimization Algorithm

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Marco Del Monte ◽  
Raffaele Meles ◽  
Christian Circi
Keyword(s):  
Optimization Algorithm ◽  
Mechanical Engineering ◽  
Initial Conditions ◽  
Metaheuristic Algorithm ◽  
Simple Formulation ◽  
Planar Case ◽  
Orbital Transfer ◽  
Colliding Bodies Optimization ◽  
The Earth ◽  
Interplanetary Trajectories

In this paper, a recent physics-based metaheuristic algorithm, the Colliding Bodies Optimization (CBO), already employed to solve problems in civil and mechanical engineering, is proposed for the optimization of interplanetary trajectories by using both indirect and direct approaches. The CBO has an extremely simple formulation and does not depend on any initial conditions. To test the performances of the algorithm, missions with remarkably different orbital transfer energies are considered: from the simple planar case, as the Earth-Mars orbital transfer, to more energetic ones, like a rendezvous with the asteroid Pallas.

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