Structural damage identification has recently become one of the most important topics for engineering structures due to its benefits in enhancing safety, reducing life-cycle cost and providing guidance for system construction and maintenance. This research investigates the accuracy of using displacement influence lines (DILs) and their derivatives (slope and curvature) for structural damage characteristics (location and severity). The method is based on static structure response, which can be measured using single or multi sensors. The study includes an analytical investigation of damage detection of single and multiple damages in a simply supported beam. The measuring point positions are also discussed in this paper. Furthermore, the advantages and disadvantages of using displacement influence lines in structural damage detection are also discussed

Structural damage detection has recently become one of the most important topics for engineering structures due
to its benefits in enhancing safety, reducing life-cycle cost and providing guidance for system construction and
maintenance. This research studies the accuracy of using rotation influence lines (RIL) and their derivatives (first
and second derivatives) for detecting structural damage characteristics (location and severity). The study includes
an analytical investigation of damage detection of multiple damages in simply supported beam. Then,
numerical studies have been conducted to investigate the effectiveness of the proposed method for damage
identification of simply supported beam (determinate structure), continuous beam (indeterminate structure)
with different damage characteristics. Furthermore, the most effective inclinometer locations and number of
inclinometers for structural damage detection on simply supported and continuous beams are reported.
Furthermore, noise intensity effects from the limited inclinometer precision, inclinometer faults and transmission
errors are discussed in this paper.

Structural damage detection has recently become one of the most important topics for engineering structures due
to its benefits in enhancing safety, reducing life-cycle cost and providing guidance for system construction and
maintenance. This research studies the accuracy of using rotation influence lines (RIL) and their derivatives (first
and second derivatives) for detecting structural damage characteristics (location and severity). The study includes
an analytical investigation of damage detection of multiple damages in simply supported beam. Then,
numerical studies have been conducted to investigate the effectiveness of the proposed method for damage
identification of simply supported beam (determinate structure), continuous beam (indeterminate structure)
with different damage characteristics. Furthermore, the most effective inclinometer locations and number of
inclinometers for structural damage detection on simply supported and continuous beams are reported.
Furthermore, noise intensity effects from the limited inclinometer precision, inclinometer faults and transmission
errors are discussed in this paper.

We numerically investigated Marangoni flow induced around a microbubble generated using a laser beam to be used as a method for enhanced fluid mixing on the microscale. We report the generated flow field at different laser powers and different positions of the laser spot relative to the bubble center. We found that flow velocities as high as 47 cm/sec are achievable when the laser spot is closest to the bubble center at a power of 1 mW. This flow velocity increases with increasing the laser power and decreases as the laser spot moves away from the bubble. Our numerical results are validated by comparing it to previously reported experimental results and shows good qualitative agreement. The results reported here indicate that photothermally induced Marangoni flow can be used as an effective mixing mechanism on the microscale.

Abstract

Introduction: Patients with mitral annular calcification (MAC) can develop transmitral gradients despite lacking the commissural fusion that typifies rheumatic mitral stenosis (MS). As the gradient worsens, dyspnea, exercise intolerance, and heart failure can develop, similar to classical MS. A proposed mechanism relates to viscous energy dissipation (VED) due to turbulence as blood flows through the diseased valve into the ventricle.

Methods: 3D-TEE images of a normal mitral valve (MV) were employed to create a generic model. Using an end-systolic frame (prior to leaflet opening) the volume enclosed by the MV was segmented and printed. Latex was applied to the resulting mold reproducing the mitral valve and annulus. Multiple copies were created. Next, calcium phantoms made of hard plastic were cemented onto various annular locations to simulate mild (P2 only), moderate (P2-P3), and severe (P1-P3 and A2) MAC. An optically neutral silicone ventricle was created and the MV was placed in its inlet, using 4 cardinal sutures and a continuous stitch to fix it in place. Latex chordae were affixed to the leaflets and commissures, and then sutured to the ventricular wall. The synthetic MVs were tested in a left heart duplicator under heart rate and stroke volume conditions similar to those at rest. Fine particles were placed in a water/glycerol solution and particle image velocimetry tracked flow across the MV and through the ventricle, and VED was calculated (Figure).

Results: Preliminary data demonstrate increased VED in MAC valves compared with normal (Figure). Further, there was a graded response with 3x VED for mild MAC (compared to normal) and 4x VED for severe MAC.

Conclusions: MAC MS is associated with increased transmitral gradients and increased VED. These energy losses may contribute to signs and symptoms of heart failure in MAC patients. Further testing is planned with protocols simulating exercise conditions and various pathologies such as HFpEF and chronic infarction.

Mechanical heart valve replacement is the preferred alternative in younger patients with severe symptomatic aortic valve disease. However, thrombus and pannus formations are common complications associated with bileaflet mechanical heart valves. This leads to risks of valve leaflet dysfunction, a life‐threatening event. In this experimental study, we investigate, using time‐resolved planar particle image velocimetry, the flow characteristics in the ascending aorta in the presence of a dysfunctional bileaflet mechanical heart valve. Several configurations of leaflet dysfunction are investigated and the induced flow disturbances in terms of velocity fields, viscous energy dissipation, wall shear stress, and accumulation of viscous shear stresses are evaluated. We also explore the ability of a new set of parameters, solely based on the analysis of the normalized axial velocity profiles in the ascending aorta, to detect bileaflet mechanical heart valve dysfunction and differentiate between the different configurations tested in this study. Our results show that a bileaflet mechanical heart valve dysfunction leads to a complex spectrum of flow disturbances with each flow characteristic evaluated having its own worst case scenario in terms of dysfunction configuration. We also show that the suggested approach based on the analysis of the normalized axial velocity profiles in the ascending aorta has the potential to clearly discriminate not only between normal and dysfunctional bilealfet heart valves but also between the different leaflet dysfunction configurations. This approach could be easily implemented using phase‐contrast MRI to follow up patients with bileaflet mechanical heart valves.

This study proposes a resilience-based design approach that considers the correlation between the resilience response of self-centering post-tensioned (SCPT) steel beam to column connections and the inelastic performance of the required energy dissipation (ED) system. A compact circular hollow steel tube (CHST) is proposed as a replaceable ED system. On the basis of existing experimental results, a detailed three-dimensional finite element modeling (3D-FEM) was carried out to identify the response of the compact CHST under half cyclic loading. A large number of numerical works ended with the extraction of design charts to determine the axial strain (ΔL/L) of the ED system before encountering post-yield buckling and/or excessive strength degradation. Accordingly, in a numerical validated reference SCPT connection, several predesigned ED systems were implemented for simulation. As a result, according to the design charts, the optimum selection of proper inherent depth to thickness (D/t) ratio and length to depth (L/D) ratio of the CHST-ED system can increase the resilience of modern self-centering steel structures. In addition, the improvement of the entire connection resilience is associated with the development of satisfactory energy dissipation capacity. Furthermore, the superior performance of the connection under sequential cyclic loading promotes the application of the proposed SCPT-ED connection in a resilient structural system.