CFD investigation of a complete floating offshore wind turbine

This chapter presents numerical computations for floating offshore wind turbines for a machine of 10-MW rated power. The rotors were computed using the Helicopter Multi-Block flow solver of the University of Glasgow that solves the Navier-Stokes equations in integral form using the arbitrary Lagrangian-Eulerian formulation for time-dependent domains with moving boundaries. Hydrodynamic loads on the support platform were computed using the Smoothed Particle Hydrodynamics method. This method is mesh-free, and represents the fluid by a set of discrete particles. The motion of the floating offshore wind turbine is computed using a Multi-Body Dynamic Model of rigid bodies and frictionless joints. Mooring cables are modelled as a set of springs and dampers. All solvers were validated separately before coupling, and the loosely coupled algorithm used is described in detail alongside the obtained results

What parameters affect left ventricular diastolic flow propagation velocity? in vitro studies using color m-mode doppler echocardiography

BACKGROUND: Insufficient data describe the relationship of hemodynamic parameters to left ventricular (LV) diastolic flow propagation velocity (Vp) measured using color M-mode Doppler echocardiography. METHODS: An in vitro LV model used to simulate LV diastolic inflow with Vp measured under conditions of varying: 1) Stroke volume, 2) heart rate (HR), 3) LV volume, 4) LV compliance, and 5) transmitral flow (TMF) waveforms (Type 1: constant low diastasis flow and Type 2: no diastasis flow). RESULTS: Univariate analysis revealed excellent correlations of Vp with stroke volume (r = 0.98), LV compliance (r = 0.94), and HR with Type 1 TMF (r = 0.97). However, with Type 2 TMF, HR was not associated with Vp. LV volume was not related to Vp under low compliance, but inversely related to Vp under high compliance conditions (r = -0.56). CONCLUSION: These in vitro findings may help elucidate the relationship of hemodynamic parameters to early diastolic LV filling

OC-057 PREVENTION OF INCISIONAL HERNIAS BY PROPHYLACTIC MESH-AUGMENTED REINFORCEMENT OF MIDLINE LAPAROTOMIES FOR ABDOMINAL AORTIC ANEURYSM TREATMENT. 5-YEAR FOLLOW-UP OF A RANDOMIZED CONTROLLED TRIAL

peer reviewedAbstract Introduction The incidence of incisional hernias (IHs) after open repair of an abdominal aortic aneurysm (AAA) is high. Several randomized controlled trials have reported favorable results with the use of prophylactic mesh to prevent IHs, without increasing complications. In this analysis we report on the results of the 60-month follow-up of the PRIMAAT trial (Ann Surg 2016; 263(4): 638–45). Methods In a prospective, multicenter, open label, randomized design, patients were randomized between prophylactic retrorectus mesh reinforcement (MESH group), and primary closure of their midline laparotomy after open AAA repair (NOMESH group). This article reports on the results of clinical follow-up after 60 months. If performed, ultrasonography or computed tomography were used for the diagnosis of IHs. Results Of the 120 randomized patients, 114 were included in the intention-to-treat analysis. Thirty-three patients in the NOMESH group (33/58–56.9%) and 34 patients in the MESH group (34/56–60.7%) were evaluated after 5 years. The cumulative incidence of IHs in the NOMESH group was 32.9% after 24 months and 49.2% after 60 months. No incisional hernias were diagnosed in the MESH group. In the NOMESH group, 21.7% (5/23) underwent reoperation within 5 years due to an IH. Conclusion Prophylactic retrorectus mesh reinforcement after midline laparotomy for the treatment of AAAs safely and effectively decreases the rate of IHs. The cumulative incidence of IHs after open AAA repair, when no mesh is used, continues to increase during the first 5 years after surgery, which leads to a substantial rate of hernia repairs

Flow propagation velocity is not a simple index of diastolic function in early filling. A comparative study of early diastolic strain rate and strain rate propagation, flow and flow propagation in normal and reduced diastolic function

BACKGROUND: Strain Rate Imaging shows the filling phases of the left ventricle to consist of a wave of myocardial stretching, propagating from base to apex. The propagation velocity of the strain rate wave is reduced in delayed relaxation. This study examined the relation between the propagation velocity of strain rate in the myocardium and the propagation velocity of flow during early filling. METHODS: 12 normal subjects and 13 patients with treated hypertension and normal systolic function were studied. Patients and controls differed significantly in diastolic early mitral flow measurements, peak early diastolic tissue velocity and peak early diastolic strain rate, showing delayed relaxation in the patient group. There were no significant differences in EF or diastolic diameter. RESULTS: Strain rate propagation velocity was reduced in the patient group while flow propagation velocity was increased. There was a negative correlation (R = -0.57) between strain rate propagation and deceleration time of the mitral flow E-wave (R = -0.51) and between strain rate propagation and flow propagation velocity and there was a positive correlation (R = 0.67) between the ratio between peak mitral flow velocity / strain rate propagation velocity and flow propagation velocity. CONCLUSION: The present study shows strain rate propagation to be a measure of filling time, but flow propagation to be a function of both flow velocity and strain rate propagation. Thus flow propagation is not a simple index of diastolic function in delayed relaxation

Classification of primary and incisional abdominal wall hernias

A classification for primary and incisional abdominal wall hernias is needed to allow comparison of publications and future studies on these hernias. It is important to know whether the populations described in different studies are comparable.Comparative StudyConsensus Development ConferenceJournal ArticleReviewSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Early Belgian experience with the Kugel patch inguinal hernia repair

The Kugel hernia repair is an open but minimally invasive, tension free repair, offering the advantages of a preperitoneal repair without the need for general anaesthesia. We report our initial experience with this technique in 25 inguinal hernia repairs. Operating time averaged 40 16 min, and one complication, a bladder tear, occurred intraoperatively. Patients were discharged after a median of 2 days and were then seen after 3 weeks and after at least one year. Three weeks postoperatively, there were two superficial skin inflammations and one haematoma. One year postoperatively no recurrences occurred but two patients complained of persistent inguinodynia. The Kugel hernia repair is a relatively new technique with a short operating time and minimal postoperative pain, but a learning curve, comparable to that of TEP has to be overcome in order to reproduce the results of its inventor

Fluid structure interaction modeling of pulsations in the fetal umbilical cord

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PREVENTION OF INCISIONAL HERNIA AFTER MIDLINE LAPAROTOMY FOR ABDOMINAL AORTIC ANEURYSM TREATMENT: A RANDOMIZED CONTROLLED TRIAL

Background: The incidence of incisional hernias (IH) after open abdominal aortic aneurysm (AAA) repair is high. Prophylactic mesh augmentation (PMA) during laparotomy closure has been proposed in high-risk patients. Methods: A multicenter prospective randomized controlled study was conducted on patients undergoing elective repair of AAA through midline laparotomy (Clinical.Trials.gov: NCT00757133). In the study group a retro-muscular PMA was performed with a large-pore polypropylene mesh (Ultrapro™, width 7.5 cm). The primary endpoint was the incidence of IH at 24 months. Results: Between February 2009 and January 2013, 120 patients were recruited at 8 Belgian centers. Patients' characteristics at baseline were similar between the groups. Operative and postoperative characteristics showed no difference in morbidity or mortality. A highly significant reduction of IH incidence was found after PMA compared to conventional closure, respectively 0% (CI: 0 % - 5.5%) versus 27.6% (CI: 16.7% - 40.9%) (P<0.0001; Fisher's exact test). The estimated "freedom of IH" curves (Kaplan-Meier estimate) were significantly different across study arms (X2=18.93, P<0.0001; Mantel-Cox test). No adverse effects were observed, apart from an increased mean (SD) time to close the abdominal wall for PMA: 46.2 min (18.6) versus 29.6 min (18.5) (P<0.001; Mann-Whitney U test). Conclusion: Prophylactic retro-muscular mesh augmentation of a midline laparotomy in AAA patients is safe and effectively prevents the development of IH, with an extra time investment of 17 minutes

CFD analysis and optimization of a liquid lead-bismuth loop target for ISOL facilities

In the context of the forthcoming next generation of Radioactive Ion Beams (RIBs) facilities based on an Isotope Separation On Line (ISOL) method, the development of production targets capable of dissipating the high power deposited by the primary beam is a major challenge. The concept of a high-power target based on a liquid Pb–Bi loop incorporating a heat-exchanger and a diffusion chamber was proposed within EURISOL DS and is being developed within the LIEBE1 project. Due to the non-static character of the target, specific hydrodynamics issues are of concern. In this paper, these issues are studied mostly based on three-dimensional (3D) Computational Fluid Dynamics analysis of the flow of the Lead Bismuth Eutectic (LBE) target, resulting in optimized designs. The concept and hydrodynamic challenges of generating RIBs from a liquid-metal-loop target irradiated with a high-power primary beam are presented. The optimization of the target design has been conducted keeping in mind the need for a fast and efficient release of short-lived isotopes. This study shows that approximately 100 ms after the proton pulse the irradiated liquid-metal is entirely and uniformly evacuated from the irradiation volume and spread in a shower of small droplets (100-μm radii), in order to reduce the diffusion length of isotopes. Solutions to deal with the typical cavitation risk due to the presence of low-pressure zones in the liquid have also been found and simulated