Error Analysis of A New Higher Order Boundary Element Method for A Uniform Flow Passing Cylinders

A higher order boundary element method(HOBEM)is presented for inviscid flow passing cylinders in bounded or unbounded domain.The traditional boundary integral equation is established with respect to the velocity potential and its normal derivative.In present work,a new integral equation is derived for the tangential velocity.The boundary is discretized into higher order elements to ensure the continuity of slope at the element nodes.The velocity potential is also expanded with higher order shape functions,in which the unknown coefficients involve the tangential velocity.The expansion then ensures the continuities of the velocity and the slope of the boundary at element nodes.Through extensive comparison of the results for the analytical solution of cylinders,it is shown that the present HOBEM is much more accurate than the conventional BEM.

Numerical analysis of submarine landslides using a smoothed particle hydrodynamics depth integral model

Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Currently, commercial calculation programs such as BING have limitations in simulating underwater soil movements. All of these processes can be consistently simulated through a smoothed particle hydrodynamics（SPH） depth integrated model. The basis of the model is a control equation that was developed to take into account the effects of soil consolidation and erosion. In this work, the frictional rheological mode has been used to perform a simulation study of submarine landslides. Time-history curves of the sliding body＇s velocity, height,and length under various conditions of water depth, slope gradient, contact friction coefficient, and erosion rate are compared; the maximum sliding distance and velocity are calculated; and patterns of variation are discussed.The findings of this study can provide a reference for disaster warnings and pipeline route selection.

Veno-Venous Extra-Corporeal Membrane Oxygenation (ECMO) in a Child with Hemoptysis and Fontan Circulation

Background: Extracorporeal membrane oxygenation is a rescue life support technique used in life threatening conditions of refractory respiratory and/or cardiac distress. Indication for extracorporeal life support in children depends on age and varies from pulmonary to cardiac pathologies. In some cases, it may be used as a bridge to a therapeutic procedure. We described here the management of respiratory failure due to hemoptysis in a child with a Fontan circulation and veno-venous extracorporeal membrane oxygenation which served as a bridge to angio-embolization. Hemoptysis can be a life threatening condition which can lead to hypovolemic shock and impaired alveolar gas exchange. The latter can result in respiratory failure and consequent asphyxia. When hemoptysis occurs in a patient with a univentricular heart and a Fontan circulation, management of this clinical situation can be challenging due to the particular physiology of the latter. Total cavopulmonary connection is a palliative surgical repair which constitutes Fontan circulation as a definitive treatment in patients with a univentricular heart. Methods: Case report description of a 16 year-old boy with a univentricular heart and a Fontan circulation who presented hemoptysis managed with a veno-venous extracorporeal membrane oxygenation (ECMO) as a bridge to angio-embolization. Results: Hemoptysis due to diffuse intra-alveolar hemorrhage from collateral circulation was successfully treated in this young patient with pulmonary vascular embolization. This allowed to wean the patient from extra-corporeal membrane oxygenation. Conclusion: Veno-venous ECMO can be life-saving as a bridge to angio-embolization for severe hemoptysis in patients with Fontan circulation. The reported case allows to underline that our multidisciplinary approach in this complex pediatric patient surely participated to improve outcome.

A prospective study to evaluate the efficacy of an intracardiac electrogram-based atrioventricular and interventricular intervals optimization method in cardiac resynchronization therapy

Background Cardiac resynchronization therapy （CRT） with biventricular pacing improves cardiac function,functional capacity and quality of life in selected patients with heart failure.The current study aimed to evaluate the efficacy of the intracardiac electrogram （IEGM）-based optimization method,QuickOptTM,in Chinese patients treated with CRT.Methods Aortic time velocity integrals （AVTI） achieved at the sensed atrioventricular （AV）,paced AV and interventricular （VV） interval settings recommended by both QuickOptTM and standard echocardiographic optimization were measured in 101 patients.Consistency and the strength of the relationship between the two timing cycle optimization methods were assessed by intra-class correlation coefficient （ICC）.Results The ICC showed good agreement and correlation with what the AVTI achieved at the optimal sensed AV （ICC=0.9683 （0.9535-0.9785））,paced AV （ICC=0.9642 （0.9475-0.9757）） and VV （ICC=0.9730 （0.9602-0.9817）） interval settings determined by the two optimization methods.The average time required by echocardiographic optimization and by QuickOptTM were （78.32±32.40） minutes and （1.98±1.64） minutes respectively （P 〈0.0001）.Conclusion The QuickOptTM algorithm provides a quicker,simpler and reliable alternative to the standard method for timing cycle optimization.（ClinicaITrial.gov Reference Number：NCT00918294）