Shock tube study of n-decane ignition at low pressures

Ignition delay times for n-decane/O2/Ar mixtures were measured behind reflected shock waves using endwall pressure and CH＊ emission measurements in a heated shock tube. The initial postshock conditions cover pressures of 0.09-0.26 MPa, temperatures of 1 227-1 536 K, and oxygen mole fractions of 3.9%-20.7% with an equivalence ratio of 1.0. The correlation formula of ignition delay dependence on pressure, temperature, and oxygen mole fraction was obtained. The current data are in good agreement with available low-pressure experimental data, and they are then compared with the prediction of a kinetic mechanism. The current measurements extend the kinetic modeling targets for the n-decane combustion at low pressures.

ANALYTICAL SOLUTION OF FILLING AND EXHAUSTING PROCESS IN PNEUMATIC SYSTEM

The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.

Effect of time bin size on accuracy of streak tube imaging lidar

Streak tube imaging lidar （STIL） is an active imaging system that has a high range accuracy with tile use of a pulsed lapser transmitter and streak tube receiver to produce 3D range inlages. This work investigates the effect of tile time bin size oil the range accuracy of STIL systems based on the peak detection algorithm. The nunlerical simulation indicates that the time bin size has a significant effect on the range aceuracy, resulting in a modified analytical estimate of the range error. An indoor experilnent with a planar target is carried out to validate the theory that shows the linear relationship between tile range error and the time bin size. Finer 3D depth iinages of a fist model are acquired by using a smaller time bin size and the best range error of 0.003 In is achieved with the optimal time bin size of 0.07 ns.

Nasogastric or nasojejunal feeding in pediatric acute pancreatitis: a randomized controlled trial

Background The aim of this study was to compare nasogastric(NG)feeding with nasojejunal(NJ)feeding when treating pediatric patients with acute pancreatitis(AP)..Methods We performed a single-center,prospective,randomized,active-controlled trial involving 77 pediatric patients with AP from April 2014 to December 2017.The patients were randomized into two groups:the NG tube feeding group(34 patients)and the NJ tube feeding group(33 patients).The primary outcome measures included the enteral nutrition intoler-ance,the length of tube feeding time,the recurrent pain of pancreatitis and complications.Results A total of 62 patients with AP(31 patients for each group)came into the final analysis.No differences were found in baseline characteristics,pediatric AP score and computed tomography severity score between the lwo groups.Three(9.7%)patients in the NG group and one(3.2%)patient in the NJ group developed intolerance(relative risk=3.00,95%confidence interval 0.33-27.29,P=0.612).The tube feeding time and length of hospital stay of the NG group were significantly shorter than those of the NJ group(P=0.016 and 0.027,respectively).No patient died in the trial.No significant differences were found in recurrent pain,complications,nutrition delivery efficacy,and side effects between the two groups.Conclusions NG tube feeding appears to be effective and safe for acute pediatric pancreatitis compared with NJ tube feeding.In addition,high qualifed,large sample sized,randomized controlled trials in pediatric population are needed.