Application of deep learning method to Reynolds stress models of channel flow based on reduced-order modeling of DNS data

Recently,the methodology of deep learning is used to improve the calculation accuracy of the Reynolds-averaged Navier-Stokes (RANS) model.In this paper,a neural network is designed to predict the Reynolds stress of a channel flow of different Reynolds numbers.The rationality and the high efficiency of the neural network is validated by comparing with the results of the direct numerical simulation (DNS),the large eddy simulation (LES),and the deep neural network (DNN) of other studies.To further enhance the prediction accuracy,three methods are developed by using several algorithms and simplified models in the neural network.In the method 1.the regularization is introduced and it is found that the oscillation and the overfitting of the results are eflectively prevented.In the method 2,y^+ is embedded in the input variable while the combination of the invariants is simplified in the method 3.From the predicted results,it can be seen that by using the first two methods,the errors are reduced.Moreover,the method 3 shows considerable advantages in the DNS trend and the smoothness of a curve.Consequently,it is concluded that the DNNs can predict effectively the anisotropic Reynolds stress and is a promising technique of the computational fluid dynamics.

Controversial protamine in dealing with acute cardiac tamponade during radiofrequency ablation

To the Editor:During radiofrequency catheter ablation(RFCA),acute cardiac tamponade is a common but life-threatening occurrence in which rapid blood accumulation in the pericardium cavity compresses the heart and causes the systemic circulation to deteriorate.Emergency percutaneous pericardiocentesis and immediate autologous blood transfusion are necessary.The administration of protamine for incessant bleeding is controversial,for pericardial blood clots may form spontaneously despite the neutralizing effects of heparin and may even necessitate thoracotomy.Our aim is to discuss the necessity and optimum time of protamine administration and to explore the means to prevent blood clot formation.

Flexible Subclavian Artery Closure for an Inadvertent Injury to the Internal Mammary Artery During Internal Jugular Vein Catheterization

Central vein catheter （CVC） placement, which is widely utilized in clinical departments, is also highly important in preoperative preparations for radiofrequency catheter ablation （RFCA）. The internal jugular vein or subclavian vein is the routine target. Arterial injury is not uncommon during the procedure but is potentially devastating in spite of the safety and advantages of the Seldinger technique. Compressing of the airway by a hematoma, as well as hemothorax, pseudoaneurysm, arteriovenous fistula, stroke, and even death, has been well-described.

Intramural Hematoma versus Thrombus： Radiation-induced Heart Disease Results in Mass Formation after Radiofrequency Ablation

Radiofrequency catheter ablation （RFCA）,albeit an effective therapy for drug-refractory atrial fibrillation （AF）,can be associated with complications in 3.9-22.0% of cases, of which cerebrovascular embolization,cardiac tamponade,and pulmonary vein stenosis are more common,and atrial hematoma is more rare.Here,we presented a case describing an elderly woman diagnosed with an intramural left atrial hematoma after AF ablation.

Successful Ablation of Moderator Band-Originated Ventricular Tachycardia at Its Ventricle Insertion Sites

To the Editor： Moderator band （MB） is a part of the septomarginal trabeculation, which not only supports the anterior papillary muscle （APM） of the tricuspid valve but also connects it to the flee wall. Nevertheless, with the advent of intracardiac echocardiography （ICE）, electrophysiologists are now aware of the arrhythmogenic role of MB besides its mechanical function. MB-originated ventricular tachycardia or ventricular fibrillation （VT/VF） is a kind of idiopathic malignant arrhythmia in the absence of structural heart disease, which is frequently triggered by a premature ventricular contraction （PVC） from the same site.