Comparing the Regression Analysis and Artificial Neural Network in Modeling the Submerged Arc Welding (SAW) Process

Abstract: 6 T Complexities of6 T 6 T submerged arc6 T 6 T welding6 T 6 T variables6 T on the one hand and its widespread use in producing the sensitive and expensive parts on the other hand have doubled the importance of precise control of its adjusting parameters. In general, in order to create high-quality joints in welding processes it is necessary to control three parameters of welding 6 T current6 T , voltage and speed precisely from various variables. On this basis, the mentioned variables have been considered as the criteria for quality of the weld joints in this study as the adjusting parameters and weld bead geometry, which include the bead height, width and penetration. Thus, the accurate equations have been proposed for estimating the weld bead height, width and penetration based on the input parameters by the regression analysis and neural network. Based on the results, the designed neural network is markedly more accurate than the regression equations, but both models have high capabilities for optimizing the parameters of submerged arc welding and also predicting the weld bead geometry for a set of input values

The Effect of Low Tidal Volume Ventilation during Cardiopulmonary Bypass on Postoperative Pulmonary Function

Background: Postoperative pulmonary dysfunction is one of the most frequent complications after cardiac surgery and it is believed to result from the use of cardiopulmonary bypass (CPB). In this study, we investigated the effect of low tidal volume ventilation during CPB on postoperative gas exchange and lung mechanics.Methods: This prospective randomized study included 100 patients undergoing elective coronary artery bypass grafting. In 50 patients, low tidal volume ventilation [tidal volume (TV) = 3 ml/kg, respiratory rate (RR) = 12/min, fraction of inspiratory oxygen (FIO2)= 1.0, positive end expiratory pressure (PEEP) = 5 cmH2O] was applied during CPB (group I); and in the other 50 patients (group II), the lungs were open to the atmosphere without ventilation. Measurements were taken preoperatively,after CPB, and before discharge.Results: Post-bypass PaO2 (just after CPB 85 versus75) was higher significantly in group I (P value < 0.05). Decrease in postoperative forced expiratory volume in 1 second (25% versus 30%) and forced vital capacity (32% versus 35%) was less significant in group I. Also, time to extubation (5 hrs versus 5.5 hrs) was shorter in group I.Conclusion: Continued low tidal volume ventilation during CPB improved post-bypass oxygenation and lung mechanics