During the operation and installation of offshore pipelines, high axial forces and pressures are experienced, and their effects cannot be neglected. In this article, the effect of internal flow velocity and functional...During the operation and installation of offshore pipelines, high axial forces and pressures are experienced, and their effects cannot be neglected. In this article, the effect of internal flow velocity and functional loads on vortex-induced vibration （VIV） response is investigated. On the basis of the Hamilton principle, a differential equation was derived to describe the motion of a pinned-pinned tensioned spanning pipeline conveying fluid. The VIV response was calculated according to DNV-RP-F105 under different functional loads. The results showed that functional loads influence free spanning pipeline VIV response by changing the natural frequency. Internal flow velocity was found less important for VIV response than other functional load factors, such as effective axial force, because the speed in reality is not high enough to be significant. The research may provide a reference for sensitivity studies of the effect of functional loads on allowable free span lengths.展开更多
Gastrointestinal (GI) bleeding refers to any hemorrhage ascribed to the pathologies of the gastrointestinal tract,extending from the mouth to the anal canal.Despite the recent improvements in the endoscopic,hemostatic...Gastrointestinal (GI) bleeding refers to any hemorrhage ascribed to the pathologies of the gastrointestinal tract,extending from the mouth to the anal canal.Despite the recent improvements in the endoscopic,hemostatic and adjuvant pharmacologic techniques,the reported mortality is still around 5%-10% for peptic ulcer bleeding and about 15%-20% for variceal hemorrhages.Although endoscopic management reduces the rates of re-bleeding,surgery,and mortality in active bleeding;early recurrence ratios still occur in around 20% of the cases even with effective initial hemostatic measures.In this quest for an alternative pro-hemostatic agent for the management of GI bleedings,Ankaferd blood stopper (ABS) offers a successful candidate,specifically for "difficult-to-manage" situations as evidenced by data presented in several studies.ABS is a standardized mixture of the plants Thymus vulgaris,Glycyrrhiza glabra,Vitis vinifera,Alpinia officinarum,and Urtica dioica.It is effective in both bleeding individuals with normal hemostatic parameters and in patients with deficient primary and/or secondary hemostasis.ABS also modulates the cellular apoptotic responses to hemorrhagic stress,as well as hemostatic hemodynamic activity.Through its effects on the endothelium,blood cells,angiogenesis,cellular proliferation,vascular dynamics,and wound healing,ABS is now becoming an effective alternative hemostatic medicine for gastrointestinal bleedings that are resistant to conventional anti-hemorrhagic measurements.The aim of this review is to outline current literature experience suggesting the place of ABS in the management of GI bleeding,and potential future controlled trials in this complicated field.展开更多
Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may p...Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may pro- duce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical si- mulations are carried out on the swirl meter. Using RNG k-e turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A coun- ter-swift flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.展开更多
Objective： To analyze reflux parameters by means of combined multichannel intraluminal impedance and pH （MII-pH） monitoring in patients with gastroesophageal reflux disease （GERD） symptoms off medication, and to ...Objective： To analyze reflux parameters by means of combined multichannel intraluminal impedance and pH （MII-pH） monitoring in patients with gastroesophageal reflux disease （GERD） symptoms off medication, and to find the reflux characteristics of Chinese GERD patients and the influences of gender, age, body posture, and body mass index （BMI） on gastroesophageal reflux （GER）. Methods： Between Dec. 2008 and May 2014, 125 patients with typical GERD symptoms were subjected to 24-h MII-pH monitoring. Twelve patients with normal MII-pH profiles were not considered for analysis. The reflux parameters of 113 GERD patients with abnormal Mll-pH results were analyzed. Results： （1） DeMeester scores were above the normal range in 46.90% （53/113） of GERD patients. Weakly acidic refluxes were prevalent in GERD patients, and the frequency of abnormal weakly acidic reflux was 75.22% （85/113）. The frequencies of abnormal symptom index （SI） and symptom association probability （SAP） were 19.47% （22/113） and 14.16% （16/113）, respectively. （2） The frequencies of DeMeester scores, the %time at pH〈4, and the numbers of reflux episodes and of long reflux episodes 〉5 min were significantly higher in male patients than in female patients. （3） The %time at pH〈4 was much higher during upright periods than during supine periods. During supine periods, 31.86% （36/113） of GERD patients had delayed bolus clearance time, compared with 19.47% （22/113） during upright periods. （4） The number of abnormal DeMeester scores, %time at pH〈4, and the number of acid refluxes during upright periods were significantly higher in obese GERD patients than in GERD patients with a normal BMI. Over- weight GERD patients also had many more acid refluxes during upright periods than GERD patients with a normal BMI Conclusions： Weakly acidic refluxes were prevalent in Chinese GERD patients. The factors male, gender, upright position, obesity （BMI〉25）, but not age, may increase the frequency and severity of GER.展开更多
基金Supported by the National Natural Science Foundation of China (No. 50879013)China National 111 Project (No.B07019)
文摘During the operation and installation of offshore pipelines, high axial forces and pressures are experienced, and their effects cannot be neglected. In this article, the effect of internal flow velocity and functional loads on vortex-induced vibration （VIV） response is investigated. On the basis of the Hamilton principle, a differential equation was derived to describe the motion of a pinned-pinned tensioned spanning pipeline conveying fluid. The VIV response was calculated according to DNV-RP-F105 under different functional loads. The results showed that functional loads influence free spanning pipeline VIV response by changing the natural frequency. Internal flow velocity was found less important for VIV response than other functional load factors, such as effective axial force, because the speed in reality is not high enough to be significant. The research may provide a reference for sensitivity studies of the effect of functional loads on allowable free span lengths.
文摘Gastrointestinal (GI) bleeding refers to any hemorrhage ascribed to the pathologies of the gastrointestinal tract,extending from the mouth to the anal canal.Despite the recent improvements in the endoscopic,hemostatic and adjuvant pharmacologic techniques,the reported mortality is still around 5%-10% for peptic ulcer bleeding and about 15%-20% for variceal hemorrhages.Although endoscopic management reduces the rates of re-bleeding,surgery,and mortality in active bleeding;early recurrence ratios still occur in around 20% of the cases even with effective initial hemostatic measures.In this quest for an alternative pro-hemostatic agent for the management of GI bleedings,Ankaferd blood stopper (ABS) offers a successful candidate,specifically for "difficult-to-manage" situations as evidenced by data presented in several studies.ABS is a standardized mixture of the plants Thymus vulgaris,Glycyrrhiza glabra,Vitis vinifera,Alpinia officinarum,and Urtica dioica.It is effective in both bleeding individuals with normal hemostatic parameters and in patients with deficient primary and/or secondary hemostasis.ABS also modulates the cellular apoptotic responses to hemorrhagic stress,as well as hemostatic hemodynamic activity.Through its effects on the endothelium,blood cells,angiogenesis,cellular proliferation,vascular dynamics,and wound healing,ABS is now becoming an effective alternative hemostatic medicine for gastrointestinal bleedings that are resistant to conventional anti-hemorrhagic measurements.The aim of this review is to outline current literature experience suggesting the place of ABS in the management of GI bleeding,and potential future controlled trials in this complicated field.
基金supported by the National Natural Science Foundation of China(51579225)
文摘Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may pro- duce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical si- mulations are carried out on the swirl meter. Using RNG k-e turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A coun- ter-swift flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.
文摘Objective： To analyze reflux parameters by means of combined multichannel intraluminal impedance and pH （MII-pH） monitoring in patients with gastroesophageal reflux disease （GERD） symptoms off medication, and to find the reflux characteristics of Chinese GERD patients and the influences of gender, age, body posture, and body mass index （BMI） on gastroesophageal reflux （GER）. Methods： Between Dec. 2008 and May 2014, 125 patients with typical GERD symptoms were subjected to 24-h MII-pH monitoring. Twelve patients with normal MII-pH profiles were not considered for analysis. The reflux parameters of 113 GERD patients with abnormal Mll-pH results were analyzed. Results： （1） DeMeester scores were above the normal range in 46.90% （53/113） of GERD patients. Weakly acidic refluxes were prevalent in GERD patients, and the frequency of abnormal weakly acidic reflux was 75.22% （85/113）. The frequencies of abnormal symptom index （SI） and symptom association probability （SAP） were 19.47% （22/113） and 14.16% （16/113）, respectively. （2） The frequencies of DeMeester scores, the %time at pH〈4, and the numbers of reflux episodes and of long reflux episodes 〉5 min were significantly higher in male patients than in female patients. （3） The %time at pH〈4 was much higher during upright periods than during supine periods. During supine periods, 31.86% （36/113） of GERD patients had delayed bolus clearance time, compared with 19.47% （22/113） during upright periods. （4） The number of abnormal DeMeester scores, %time at pH〈4, and the number of acid refluxes during upright periods were significantly higher in obese GERD patients than in GERD patients with a normal BMI. Over- weight GERD patients also had many more acid refluxes during upright periods than GERD patients with a normal BMI Conclusions： Weakly acidic refluxes were prevalent in Chinese GERD patients. The factors male, gender, upright position, obesity （BMI〉25）, but not age, may increase the frequency and severity of GER.
