Wicking geotextile(WG)is considered as a possible countermeasure to reduce water content in unsaturated soil.In this research,rainfall tests were carried out to verify the drainage performance of WG.And capillary rise...Wicking geotextile(WG)is considered as a possible countermeasure to reduce water content in unsaturated soil.In this research,rainfall tests were carried out to verify the drainage performance of WG.And capillary rise tests were conducted to study the effect of WG on the prevention of capillary rise.Test results indicated that WG with good drainage performance could drain gravitational and capillary water out of kaolinite soil.For kaolinite soil column with water content of 12%and compaction degree of 90%,the whole process of capillary rise in soil column with a layer of WG was a typical two-stage mode,and the maximum capillary height was about 380 mm,which provided that the WG could work as a barrier to prevent capillary rise effectively.In addition,the total vertical influential regions of WG in kaolinite soil above and below the WG layer were 400 and 100 mm,respectively.展开更多
The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vert...The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.展开更多
In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54&#...In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54×106. The calculations were performed by means of solving the 2-D Unsteady Reynolds-Averaged Navier-Stokes （URANS） equations with a k-ε turbulence model. The calculated results, produced flow structure drag and lift coefficients, as well as Strouhal numbers. The findings were in good agreement with previous published data, which also supplied us with a good understanding of the flow across cylinders of different high Reynolds numbers. Meanwhile, an effective measure was presented to control the lift force on a cylinder, which points the way to decrease the vortex induced vibration of marine structure in future.展开更多
AIM: To characterize the effects of age on the mechanisms underlying the common condition of esophageal dysphagia in older patients, using detailed manometric analysis. METHODS: A retrospective case-control audit was ...AIM: To characterize the effects of age on the mechanisms underlying the common condition of esophageal dysphagia in older patients, using detailed manometric analysis. METHODS: A retrospective case-control audit was performed on 19 patients aged ≥ 80 years (mean age 85 ± 0.7 year) who underwent a manometric study for dysphagia (2004-2009). Data were compared with 19 younger dysphagic patients (32 ± 1.7 years). Detailed manometric analysis performed prospectively included basal lower esophageal sphincter pressure (BLESP), pre-swallow and nadir LESP, esophageal body pressures and peristaltic duration, during water swallows (5 mL) in right lateral (RL) and upright (UR) postures and with solids. Data are mean ± SE; a P-value < 0.05 was considered significant. RESULTS: Elderly dysphagic patients had higher BLESP than younger patients (23.4 ± 3.8 vs 14.9 ± 1.2 mmHg; P < 0.05). Pre-swallow LESP was elevated in the elderly in both postures (RL: 1 and 4 s P = 0.019 and P = 0.05; UR: P < 0.05 and P = 0.05) and solids (P < 0.01). In older patients, LES nadir pressure was higher with liquids (RL: 2.3 ± 0.6 mmHg vs 0.7 ± 0.6 mmHg, P < 0.05; UR: 3.5 ± 0.9 mmHg vs 1.6 ± 0.5 mmHg, P = 0.01) with shorter relaxation after solids (7.9 ± 1.5 s vs 9.7 ± 0.4 s, P = 0.05). No age-related differences were seen in esophageal body pressures or peristalsis duration. CONCLUSION: Basal LES pressure is elevated and swallow-induced relaxation impaired in elderly dysphagic patients. Its contribution to dysphagia and the effects of healthy ageing require further investigation.展开更多
基金Projects(41872240,41672280)supported by the National Natural Science Foundation of ChinaProject(2016-1-16-2)supported by Science and Technology Project of Jilin Province Transportation,ChinaProject(SJCX18-0052)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘Wicking geotextile(WG)is considered as a possible countermeasure to reduce water content in unsaturated soil.In this research,rainfall tests were carried out to verify the drainage performance of WG.And capillary rise tests were conducted to study the effect of WG on the prevention of capillary rise.Test results indicated that WG with good drainage performance could drain gravitational and capillary water out of kaolinite soil.For kaolinite soil column with water content of 12%and compaction degree of 90%,the whole process of capillary rise in soil column with a layer of WG was a typical two-stage mode,and the maximum capillary height was about 380 mm,which provided that the WG could work as a barrier to prevent capillary rise effectively.In addition,the total vertical influential regions of WG in kaolinite soil above and below the WG layer were 400 and 100 mm,respectively.
文摘The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.
基金Foundation item： Supported by Supported by the National Natural Science Foundation of China （Grant No. 51009070）.
文摘In this paper, 2-D computational analyses were conducted for unsteady high Reynolds number flows around a smooth circular cylinder in the supercritical and upper-transition flow regimes, i.e. 8.21×104〈Re〈1.54×106. The calculations were performed by means of solving the 2-D Unsteady Reynolds-Averaged Navier-Stokes （URANS） equations with a k-ε turbulence model. The calculated results, produced flow structure drag and lift coefficients, as well as Strouhal numbers. The findings were in good agreement with previous published data, which also supplied us with a good understanding of the flow across cylinders of different high Reynolds numbers. Meanwhile, an effective measure was presented to control the lift force on a cylinder, which points the way to decrease the vortex induced vibration of marine structure in future.
文摘AIM: To characterize the effects of age on the mechanisms underlying the common condition of esophageal dysphagia in older patients, using detailed manometric analysis. METHODS: A retrospective case-control audit was performed on 19 patients aged ≥ 80 years (mean age 85 ± 0.7 year) who underwent a manometric study for dysphagia (2004-2009). Data were compared with 19 younger dysphagic patients (32 ± 1.7 years). Detailed manometric analysis performed prospectively included basal lower esophageal sphincter pressure (BLESP), pre-swallow and nadir LESP, esophageal body pressures and peristaltic duration, during water swallows (5 mL) in right lateral (RL) and upright (UR) postures and with solids. Data are mean ± SE; a P-value < 0.05 was considered significant. RESULTS: Elderly dysphagic patients had higher BLESP than younger patients (23.4 ± 3.8 vs 14.9 ± 1.2 mmHg; P < 0.05). Pre-swallow LESP was elevated in the elderly in both postures (RL: 1 and 4 s P = 0.019 and P = 0.05; UR: P < 0.05 and P = 0.05) and solids (P < 0.01). In older patients, LES nadir pressure was higher with liquids (RL: 2.3 ± 0.6 mmHg vs 0.7 ± 0.6 mmHg, P < 0.05; UR: 3.5 ± 0.9 mmHg vs 1.6 ± 0.5 mmHg, P = 0.01) with shorter relaxation after solids (7.9 ± 1.5 s vs 9.7 ± 0.4 s, P = 0.05). No age-related differences were seen in esophageal body pressures or peristalsis duration. CONCLUSION: Basal LES pressure is elevated and swallow-induced relaxation impaired in elderly dysphagic patients. Its contribution to dysphagia and the effects of healthy ageing require further investigation.
