Search results for " WAVE"
showing 10 items of 2296 documents
Complex power distribution analysis in plates covered with passive constrained layer damping patches
2012
International audience; The vibration of a plate partially covered with a passive constrained layer damping (PCLD) patch is studied from an energetic point of view. The damped plate is excited by an acoustic plane wave. The study is done with a numerical two-dimensional multilayer plate model. Results of the present model are compared to those obtained with three-dimensional finite element models. It is shown that the present model gives accurate results, even for the layer's inner behavior. It is less expansive in terms of computational cost; hence, it can simulate efficiently the structure for higher frequencies. Mathematical formulas for complex mechanical power are presented, and the li…
Global-Local model for guided wave scattering problems with application to defect characterization in built-up composite structures
2020
Abstract Predicting scattering of elastic guided waves in multi-layered solid plates with geometrical and/or material discontinuities is of great interest to many fields, including ultrasonic-based Non-Destructive Testing (NDT) and health monitoring of critical structural components (SHM). The problem is complicated by the multimode and dispersive behaviour of the guided waves. This paper describes a unified Global-Local (GL) approach that is computationally efficient in cases that can be very complex in terms of geometry and/or material properties. One example of this is a composite built-up structure. The proposed GL procedure discretizes the “local” region with the scattering discontinui…
P and R Wave Detection in Complete Congenital Atrioventricular Block
2009
Complete atrioventricular block (type III AVB) is characterized by an absence of P wave transmission to ventricles. This implies that QRS complexes are generated in an autonomous way and are not coordinated with P waves. This work introduces a new algorithm for the detection of P waves for this type of pathology using non-invasive electrocardiographic surface leads. The proposed algorithm is divided into three stages. In the first stage, the R waves located by a QRS detector are used to generate the RR series and time references for the other stages of the algorithm. In the second stage, the ventricular activity (QT segment) is removed by using an adaptive filter that obtains an averaged pa…
Diagnostic performance of 2D-shear wave elastography in the diagnosis of breast cancer: a clinical appraisal of cutoff values
2022
Purpose To assess the role of 2D-shear wave elastography (2D-SWE) in differentiating benign from malignant focal breast lesions (FBLs), providing new vendor-specific cutoff values. Methods 158 FBLs (size: 3.5-50 mm) detected in 151 women (age: 21-87 years) were prospectively evaluated by means 2D-SWE. For each lesion, an expert radiologist assessed US BI-RADS category and calculated the following four 2D-SWE parameters: (1) elasticity maximum (E-max); (2) mean elasticity (E-mean); (3) minimum elasticity (E-min); (4) elasticity ratio (E-ratio). US-guided core-biopsy was considered as standard of reference for all the FBLs classified as BI-RADS 4 or 5. For each 2D-SWE parameter, the optimal c…
Is local stiffness, as measured by radio frequency, more sensitive than intima-media thickness?
2013
Aim: The aim of our study was to explore the changes in common carotid arterial intima-media thickness (CCA IMT) and local arterial stiffness to evaluate, non-invasively, early vascular disease in patients with cardiovascular (CV) risk factors and "normal" carotid IMT (6.05 m/s better identified, among patients with IMT <0.9mm, those with cardiovascular risk factors (sensitivity 82.0 % specificity 62.0 %; AUC 0.73). Conclusion. Increased stiffness is a result of change both in quantity and quality of the arterial wall. Arterial functional changes and distention alterations may herald the onset of vascular disease before manifestation of symptoms or detection of preclinical atherosclerotic l…
Possible misclassification of cardiovascular risk by SCORE in antisynthetase syndrome: results of the pilot multicenter study RI.CAR.D.A
2020
Abstract Objectives To test the ability of an established traditional cardiovascular (CV) risk prediction score [Systematic COronary Risk Evaluation (SCORE)] and its EULAR modified version (mSCORE) to identify antisynthetase syndrome (ASyS) patients at high CV risk and to examine for the first time associations of CV and cerebrovascular surrogate markers with clinical and immunological ASyS parameters. Methods SCORE/mSCORE and the gold standard marker of aortic stiffness [carotid-femoral pulse wave velocity (cfPWV)] were examined in ASyS patients and healthy controls. Moreover, sonography of the common- (CCA) and internal- (ICA) carotid arteries was performed in subsets of both groups, eval…
Visual performance of the Akreos Adapt AO intraocular lens in patients with different corneal profiles measured with an adaptive optics visual simula…
2012
AIMS: To evaluate the visual performance of an aberration-free intraocular lens (IOL) in patients with different corneal profiles using adaptive optics visual simulation. METHODS: A crx1 adaptive optics visual simulator was used to simulate the aberration pattern of an aberration-free IOL combined with five corneal profiles: virgin corneas and corneas with low and high myopic ablations and low and high hyperopic ablations. Ten eyes of 10 subjects were evaluated, and monocular distance visual acuity (VA) at 100%, 50% and 10% of contrast was measured. RESULTS: At 100% of contrast, no differences were found in VA values among virgin corneas, low and high myopic ablations and low hyperopic abla…
Effect of Simulated IOL Tilt and Decentration on Spherical Aberration After Hyperopic LASIK for Different Intraocular Lenses
2011
PURPOSE: To evaluate visual quality differences among intraocular lenses (IOLs) in patients with previous hyperopic laser ablations and to assess the impact of decentration and tilt of IOLs on visual quality. METHODS: An adaptive optics visual simulator was used to simulate the wavefront aberration pattern of one aberration-correcting IOL (AcrySof IQ SN60WF, Alcon Laboratories Inc) and two spherical IOLs with different amounts of positive spherical aberration (Akreos Adapt [Bausch & Lomb] and Triplato [AJL Ophthalmic]) in five situations—centered, 0.2 mm and 0.4 mm of decentration, and 2° and 4° of tilt—in two groups: simulated low hyperopic laser corneal ablation (low hyperopia group)…
Visual simulation through an aspheric aberration-correcting intraocular lens in subjects with different corneal profiles using adaptive optics.
2013
The aim of this study was to analyse the visual quality of the AcrySof IQ SN60WF® intraocular lens (IOL) when combined with different corneal profiles. Ten eyes of 10 participants with no prior history of refractive or cataract surgery were evaluated. An adaptive optics visual simulator was used to simulate the wavefront aberration pattern of an aspheric aberration-correcting IOL (AcrySof IQ SN60WF®). Normal corneas (group A), low and high myopic corneal ablations (groups B and C, respectively) and low and high hyperopic corneal ablations (groups D and E, respectively) were also simulated. Monocular distance visual acuities at 100, 50 and 10 per cent of contrast were measured. At 100, 50 an…
Lentes de contato corneoesclerais adaptadas em córneas irregulares após cirurgia LASIK
2018
ABSTRACT Purpose: We aimed to describe the outcomes of corneoscleral contact lens fitting with multi-aspherical geometry designs in patients with irregular corneas after laser-assisted in situ keratomileusis (LASIK). Methods: This was a retrospective series of 18 patients (age, 26-38 years) selected from an eye clinic database. Participants were required to have unsatisfactory visual acuity with their current contact lenses or spectacles after LASIK for myopia correction. All patients were fitted with corneoscleral contact lenses designed to correct corneal surface irregularities. A diagnostic trial set was used for fitting, and assessments were performed according to a standardized methodo…