scholarly journals Reconstructing the wave speed and the source

2021 ◽  
Author(s):  
Amin Boumenir ◽  
Vu Kim Tuan
Keyword(s):  
Inverse Problem ◽  
Wave Equation ◽  
Wave Speed ◽  
Simple Procedure ◽  
Single Point ◽  
Spectral Estimation ◽  
New Method ◽  
Estimation Techniques ◽  
Nodal Lines

We are concerned with the inverse problem of recovering the unknown wave speed and also the source in a multidimensional wave equation. We show that the wave speed coefficient can be reconstructed from the observations of the solution taken at a single point. For the source, we may need a sequence of observation points due to the presence of multiple spectrum and nodal lines. This new method, based on spectral estimation techniques, leads to a simple procedure that delivers both uniqueness and reconstruction of the coefficients at the same time.

A NEW METHOD FOR THE SOLUTION OF AN INVERSE PROBLEM FOR THE WAVE EQUATION

1994 ◽  
Vol 04 (05) ◽  
pp. 741-754
Author(s):  
V.I. AGOSHKOV ◽  
F. MAGGIO
Keyword(s):  
Inverse Problem ◽  
Wave Equation ◽  
Approximate Solution ◽  
Iterative Process ◽  
Numerical Experiments ◽  
New Method

In this paper we consider an inverse problem for the wave equation. We prove the solvability of the problem and derive the iterative process for the computation of the approximate solution. We present the results of two numerical experiments.

Windkesselness of coronary arteries hampers assessment of human coronary wave speed by single-point technique

2008 ◽  
Vol 295 (2) ◽  
pp. H482-H490 ◽  
Author(s):  
Christina Kolyva ◽  
Jos A. E. Spaan ◽  
Jan J. Piek ◽  
Maria Siebes
Keyword(s):  
Coronary Arteries ◽  
Wave Speed ◽  
Single Point ◽  
Coronary Vessels ◽  
Distal Segment ◽  
Doppler Velocity ◽  
Healthy Human ◽  
Catheterization Laboratory ◽  
Before And After ◽  
Local Wave

A novel single-point technique to calculate local arterial wave speed ( SPc) has recently been presented and applied in healthy human coronary arteries at baseline flow. We investigated its applicability for conditions commonly encountered in the catheterization laboratory. Intracoronary pressure (Pd) and Doppler velocity ( U) were recorded in 29 patients at rest and during adenosine-induced hyperemia in a distal segment of a normal reference vessel and downstream of a single stenosis before and after revascularization. Conduit vessel tone was minimized with nitroglycerin. Microvascular resistance (MR) and SPc were calculated from Pd and U. In the reference vessel, SPc decreased from 21.5 m/s (SD 8.0) to 10.5 m/s (SD 4.1) after microvascular dilation ( P < 0.0001). SPc was substantially higher in the presence of a proximal stenosis and decreased from 34.4 m/s (SD 18.2) at rest to 27.5 m/s (SD 13.4) during hyperemia ( P < 0.0001), with a concomitant reduction in Pd by 20 mmHg and MR by 55.4%. The stent placement further reduced hyperemic MR by 26% and increased Pd by 26 mmHg but paradoxically decreased SPc to 13.1 m/s (SD 7.7) ( P < 0.0001). Changes in SPc correlated strongly with changes in MR ( P < 0.001) but were inversely related to changes in Pd ( P < 0.01). In conclusion, the single-point method yielded erroneous predictions of changes in coronary wave speed induced by a proximal stenosis and distal vasodilation and is therefore not appropriate for estimating local wave speed in coronary vessels. Our findings are well described by a lumped reservoir model reflecting the “windkesselness” of the coronary arteries.

scholarly journals IPG as a new method to improve the agility of the initial analysis of the inventive design

2021 ◽  
Vol 49 (3) ◽  
pp. 549-562
Author(s):  
Masih Hanifi ◽  
Hicham Chibane ◽  
Rémy Houssin ◽  
Denis Cavallucci
Keyword(s):  
Inverse Problem ◽  
Design Method ◽  
New Method ◽  
Significant Progress ◽  
Initial Analysis ◽  
The Subject ◽  
Time Required

TRIZ method has long proven its value without appearing to the industrial world as inevitable. Design researchers have therefore addressed the limitations of the TRIZ method and have overcome them with more systematic approaches. Among these, the Inventive Design Method (IDM) has been the subject of several articles and put into practice in the industry. It is considered an improvement over TRIZ but still suffers from some drawbacks in terms of the time-consuming nature of its implementation. We focused on the IDM process by trying to both identify its areas of inefficiencies while attempting to preserve the quality of its deliverables. Our approach consists of applying the precepts of Lean to IDM. The result is the Inverse Problem Graph (IPG) method, inspired by IDM, but offering significant progress in reducing the time required to mobilize experts while preserving its inventive outcomes. This article outlines our approach for the construction of this new method.

scholarly journals Discrete regularization and convergence of the inverse problem for 1+1 dimensional wave equation

2019 ◽  
Vol 13 (3) ◽  
pp. 575-596 ◽  
Author(s):  
Jussi Korpela ◽  
◽  
Matti Lassas ◽  
Lauri Oksanen ◽  
Keyword(s):  
Inverse Problem ◽  
Wave Equation ◽  
Dimensional Wave
Sign in / Sign up

Export Citation Format

Share Document