Objective This study sought to quantify the learning curve for the blind bedside postpyloric placement of a spiral tube in critically ill patients. Methods We retrospectively analysed 127 consecutive experiences of three intensivists who performed comparable procedures of blind bedside postpyloric placement of a spiral tube subsequent to failed self-propelled transpyloric migration in a multicentre study. Each intensivist’s cases were divided chronologically into two groups for analysis. The assessment of the learning curve was based on efficiency and safety outcomes. Results All intensivists achieved postpyloric placement for over 80% of their patients. The junior intensivist showed major improvement in both efficiency and safety outcomes, and the learning curve for both outcomes was approximately 20 cases. The junior intensivist showed a significant increase in the success rate of proximal jejunum placement and demonstrated a substantial decrease in the major adverse tube-associated events rate. The time to insertion significantly decreased in each intensivist as case experience accumulated. Conclusions Blind bedside postpyloric placement of a spiral tube involves a significant learning curve, indicating that this technique could be readily acquired by intensivists with no previous experience using an adequate professional training programme.

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The added mass, drag and drag coefficient of a uniform and accelerated motion projectile in viscous incompressible fluid were calculated by numerical simulation and dynamic mesh method. The effect of velocity and acceleration on the added mass, drag and drag coefficient of the projectile in a launch tube was investigated. The results show that the variation rules of added mass, drag and drag coefficient are basically the same when the projectile moves at different speeds. The added mass, drag and drag coefficient become smaller and drag becomes bigger with the increase of speed. The variation rules of the added mass, drag and drag coefficient are the same as uniform motion when the projectile moves at different accelerations. The added mass and drag coefficient become smaller and drag becomes bigger with the increase of acceleration. These reveal that the motion region, velocity and acceleration have some effect on the added mass, drag and drag coefficient.

12 kinds of automotive radiator cell models were simulated at different air inlet velocities using CFD software Fluent. The distributed drag coefficients of each cell model were obtained by least squares method. Then the whole radiator model whose fins region was replaced by the porous media was simulated. The numerical results were validated by experiments which indicate that the porous media method is reliable. The study shows that the radiator heat dissipation is significantly influenced by fin structure and the model with a fin space of 1.4mm and a louver angle of 23o has the best cooling effect.