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In order to study the effect of different types of fibers on the bending properties of geopolymer concrete (GPC), a series of fiber‐reinforced geopolymer concrete (FRGPC) samples were prepared, and their flexural properties were evaluated by four point bending test and bending toughness evaluation index. Then, based on the fiber characteristic value (λ), a new bending strength prediction model and a three‐dimensional (3D) curved surface prediction model of the bending toughness of FRGPC are proposed and fitted. Finally, a new method for the selection of fibers in GPC is designed by calculating the derivative of the quadratic relationship between fiber reinforcement factor (S) and λ. The results show that all types of fibers have a certain effect on improving the bending strength of GPC samples, and the lifting rate is end‐hook steel fiber (SF), basalt fiber (BF), and short polyethylene polypropylene fiber (SPPF), from high to low. Mixing the above types of fibers with long polypropylene fibers (LPPF) will produce better performance. Among them, the hybrid fiber‐containing SF has the best performance. The bending performance prediction model deduced in this paper has a good correlation coefficient, which can be used to predict the bending performance of FRGPC. By making dS/dλ = 0 can calculate the optimal λ, and this λ can maximize the parameter S and guide the selection of optical fibers. [ABSTRACT FROM AUTHOR]

The fluid dynamics of the multiphase flow induced by water entry of high speed projectiles with various heads are different. Numerical simulation for modeling the high-speed water entry problem of projectiles with different heads at an initial impact velocity was performed. Finite Volume Method was introduced to solve the Reynolds Averaged Navier-Stokes equations, and the motion of the projectiles and cavity formation were obtained. The results showed that the cavity radius was related to the angle and the drag coefficient of the cone heads. The distribution of pressure coefficient on the cone and velocity around the shoulder of the projectiles were also obtained. During the initial stage of the water entry, there will be an extremely high pressure load. When the angle of the cone head is larger, the pressure gets higher, the pressure coefficient is larger, and the velocity of the water which is arranged by the projectile is higher. [ABSTRACT FROM AUTHOR]

AbstractMiniaturization and integration of electronic equipment in aircraft have resulted in a substantial increase in thermal load. However, aircraft often experience acceleration maneuvering flights in supergravity environments, which makes comprehensive research on thermal management under supergravity conditions necessary. The influence of gravity on the thermal storage properties of composite phase change materials doped with graphene nanoparticles (GNP-PCM) was investigated in this study by simulation. Under 2g, 4g, 6g, 8g, and 10g gravity conditions, the melting time is reduced by 14.86%, 27.05%, 33.31%, 37.00%, and 39.79%, respectively, compared with normal gravity conditions. Moreover, the integration of the PCM with a thermoelectric power system facilitated waste heat utilization. Incorporating GNPs markedly enhances power generation efficiency under 10g supergravity conditions. With an open-circuit voltage of 0.8 V and a maximum output power of 0.11 W, the power generation reached 81.62 J, which is 53.91% higher than that of pure PCM. This enhancement can be attributed to the improved natural convection and accelerated melting rate facilitated by the GNPs. This study elucidates the underlying physical mechanisms affecting the melting rate of PCM under increased gravity conditions. Furthermore, coupling PCM with a thermal power generation system provides a rational approach for the reuse of waste heat. [ABSTRACT FROM AUTHOR]

Objective: To investigate the clinical efficacy of continuous irrigation combined with closed thoracic drainage for esophagojejunal anastomotic fistula (EJAF) complicated with mediastinal, thoracic and abdominal infection after total gastrectomy., Methods: Clinical data of 22 EJAF patients complicated with mediastinal, thoracic and abdominal infection after radical gastrectomy at Department of General Surgery of the 901th Hospital of PLA from June 2012 to May 2018 were retrospectively analyzed. Case inclusion criteria:(1) gastric adenocarcinoma confirmed by preoperative endoscopic pathology undergoing radical total gastrectomy without severe organ dysfunction;(2)EJAF complicated with mediastinal, thoracic and abdominal infections diagnosed by postoperative radiography, the presence of pleural effusion confirmed by CT and ultrasound. Among them, 10 cases were treated with simple thoracic closed drainage (single drainage group); 12 cases received same closed thoracic drainage, and a rubber catheter was placed next to the closed thoracic drainage tube in the same sinus. A 0.9% sodium chloride solution was applied in continuous drip irrigation with drip velocity at 50 to 100 ml/h(continuous flushing plus drainage group). Infection indicators, anastomotic fistula healing time and related clinical indicators were compared between the two groups., Results: In the simple drainage group, 5 cases were males, age was (61.9±10.7) years old, 4 cases received laparoscopic surgery, 6 cases received open surgery, 6 cases were EJAF grade III, 4 cases were EJAF IV. In continuous flushing and drainage group, 6 cases were males, age was (61.7±11.0) years old, 7 cases received laparoscopic surgery, 5 cases received open surgery, 6 cases were EJAF grade III, and 6 cases were EJAF grade IV. Baseline data including gender, age, underlying diseases, preoperative hematological examination indexes, surgical methods, tumor TNM stage and EJAF grade were not significantly different between the two groups (all P>0.05). When postoperative EJAF was complicated with mediastinal, thoracic and abdominal infection, biochemical parameters including white blood cell, procalcitonin, C-reactive protein were not significantly different between two groups (all P>0.05). All patients of both groups achieved clinical cure without death. Compared with the simple drainage group after closed thoracic drainage, the continuous irrigation plus drainage group had significantly shorter duration of infection parameters returning to normal levels [white blood cell count: (6.8 ± 2.0) days vs.(10.5±3.0) days, t=4.062, P<0.001; procalcitonin: (7.5±1.0) days vs. (9.2±1.9) days, t=3.236, P=0.040; C-reactive protein: (8.8±1.0) days vs. (11.2±1.5) days, t=5.177, P<0.001], meanwhile time in surgical ICU [(4.9±2.5) days vs. (9.9±6.7) days, t=2.935, P=0.006], healing time of fistula [(42.9±12.5) days vs. (101.8±53.2) days, t=4.187, P=0.001] and total postoperative hospital stay [(62.3±15.8) days vs. (119.7 ±59.4) days, t=3.634, P=0.002] were significantly shorter, and total hospitalization cost was significantly lower (median 86 000 yuan vs. 124 000 yuan, Z=2.063, P=0.040) in the continuous irrigation plus drainage group., Conclusion: The continuous closed thoracic drainage with 0.9% sodium chloride solution can accelerate infection control and remission of EJAF patients complicated with mediastinal, thoracic and abdominal infections, and shorten the healing time of anastomotic fistula.