The submersible pumping unit is a new type of pumping system for lifting formation fluids from onshore oil wells, and the identification of its working condition has an important influence on oil production. In this p...The submersible pumping unit is a new type of pumping system for lifting formation fluids from onshore oil wells, and the identification of its working condition has an important influence on oil production. In this paper we proposed a diagnostic method for identifying the working condition of the submersible pumping system. Based on analyzing the working principle of the pumping unit and the pump structure, different characteristics in loading and unloading processes of the submersible linear motor were obtained at different working conditions. The characteristic quantities were extracted from operation data of the submersible linear motor. A diagnostic model based on the support vector machine （SVM） method was proposed for identifying the working condition of the submersible pumping unit, where the inputs of the SVM classifier were the characteristic quantities. The performance and the misjudgment rate of this method were analyzed and validated by the data acquired from an experimental simulation platform. The model proposed had an excellent performance in failure diagnosis of the submersible pumping system. The SVM classifier had higher diagnostic accuracy than the learning vector quantization （LVQ） classifier.展开更多
A transient multiphase CFD （computational fluid dynamics） model was set up to investigate the main causes which lead to cavitation in PD （positive displacement） reciprocating pumps. Many authors agree on distingui...A transient multiphase CFD （computational fluid dynamics） model was set up to investigate the main causes which lead to cavitation in PD （positive displacement） reciprocating pumps. Many authors agree on distinguishing two different types of cavitation affecting PD pumps： flow induced cavitation and cavitation due to expansion. The flow induced cavitation affects the zones of high fluid velocity and consequent low static pressure e.g. the valve-seat volume gap while the cavitation due to expansion can be detected in zones where the decompression effects are important e.g. in the vicinity of the plunger. This second factor is a distinctive feature of PD pumps since other devices such as centrifugal pumps are only affected by the flow induced type. Unlike what has been published in the technical literature to date, where analysis of positive displacement pumps are based exclusively on experimental or analytic methods, the work presented in this paper is based entirely on a CFD approach, it discusses the appearance and the dynamics of these two phenomena throughout an entire pumping cycle pointing out the potential of CFD techniques in studying the causes of cavitation and assessing the consequent loss of performance in positive displacement pumps.展开更多
An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciproc...An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciprocating pumps discussed are the piston and plunger types. Rotary pumps addressed are gear( external and internal),vane,lobe,screw,and liquid ring pumps. To put the relative pump sizes in perspective,attention is fixed on the rotors or reciprocating elements of PD pumps,just as impellers indicate the sizes of rotodynamic pumps. The size of a PD pump is found from a dimensionless combination of displacement flow rate,rotative speed and diameter. The flow rate,head( or pressure rise) and power are related through the component efficiencies. The cavitation coefficient,often close to unity,connects the rotor tip speed or piston speed with the required NPSH,which can also be affected by the pressure rise of the pump due to leakage across the internal clearances. Operational effects due to cavitation,ingestion of gas or abrasives,and viscous and non-Newtonian fluids are discussed.展开更多
The use of non-steroidal anti-inflammatory drugs(NSAIDs) is widespread worldwide thanks to their analgesic, anti-inflammatory and antipyretic effects. However, even more attention is placed upon the recurrence of dige...The use of non-steroidal anti-inflammatory drugs(NSAIDs) is widespread worldwide thanks to their analgesic, anti-inflammatory and antipyretic effects. However, even more attention is placed upon the recurrence of digestive system complications in the course of their use. Recent data suggests that the complications of the lower gastro-intestinal tract may be as frequent and severe as those of the upper tract. NSAIDs enteropathy is due to enterohepatic recycling of the drugs resulting in a prolonged and repeated exposure of the intestinal mucosa to the compound and its metabolites. Thus leading to so-called topical effects, which, in turn, lead to an impairment of the intestinal barrier. This process determines bacterial translocation and toxic substances of intestinal origin in the portal circulation, leading to an endotoxaemia. This condition could determine a liver inflammatory response and might promote the development of nonalcoholic steatohepatitis, mostly in patients with risk factors such as obesity, metabolic syndrome and a high fat diet, which may induce a small intestinal bacterial overgrowth and dysbiosis. This alteration of gut microbiota may contribute to nonalcoholic fatty liver disease and its related disorders in two ways: firstly causing a malfunction of the tight junctions that play a critical role in the increase of intestinal permeability, and then secondly leading to the development of insulin resistance, body weight gain, lipogenesis, fibrogenesis and hepatic oxidative stress.展开更多
BaCe0.8Pr0.2O3-α ceramic was synthesized by high temperature solid-state reaction. The structural characteristics and the phase purity of the crystal were determined using powder X-ray diffraction analysis. By using ...BaCe0.8Pr0.2O3-α ceramic was synthesized by high temperature solid-state reaction. The structural characteristics and the phase purity of the crystal were determined using powder X-ray diffraction analysis. By using the methods of AC impedance spectroscopy, gas concentration cell and electrochemical pumping of hydrogen, the conductivity and ionic transport number of BaCe0.8Pr0.2O3-α were measured, and the electrical conduction behavior of the material was investigated in different gases in the temperature range of 500-900℃. The results indicate that the material was of a single perovskite-type orthorhombic phase. From 500℃ to 900 ℃, electronic-hole conduction was dominant in dry and wet oxygen, air or nitrogen, and the total conductivity of the material increased slightly with increasing oxygen partial pressure in the oxygen partial pressure range studied. Ionic conduction was dominant in wet hydrogen, and the total conductivity was about one or two orders of magnitude higher than that in hydrogen-free atmosphere （oxygen, air or nitrogen）展开更多
Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic da...Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic damage. So we use on pump beating heart technique to supplement off-pump CABG. Methods Based on 860 off-pump CABG cases between Aug 1998 to Aug 2000. From Aug 1999 to Aug 2000, 46 CABG cases were performed with on pump beating heart technique at Mani-pal Hospital Heart Foundation, Bangalore, India. All surgeries were performed through a median sternotomy. Exposure techniques were tailored to individual vessels and cardiac regions and local immobilization was performed with octopus. Vascular control was achieved with occluders and shunts. Total cardiopulmonary bypass (CPB) was established before or during CABG and normolthemia was used. Results Among 46 on -pump beating heart CABG patients, 26 patients used CPB before or during OP - CABG because of unstable hemodynamics and electric instability , 7 had very deep intramyocardial left anterior descending arteries, 5 patients had poor LV function (LVEF < 30 % ), 8 patients had cardiomegaly. The average number of grafts was 3.5. No operative mortality. Three patients had postoperative myocardial infarction. Anesthetic time 4. 5±1. 2 hours, extubation time 10±2. 5 hours, blood lost 680±230 mL, blood requirement 540±150 mL, preoperative LVEF 50. 3±13 % , postoperative LVEF 64. 1±14 %, ICU stay 1. 5±0. 5 days, hospi- tal stay 9.2±1.8 days. Conclusion Complete coronary revascularization with on pump beating heart is a supplement for off - pump CABG when it is not feasible. It eliminates intraoperative globe myocardial ischemia and avoids transient myocardial injury during cardioplegic arrest and myocardial reperfusion.展开更多
文摘The submersible pumping unit is a new type of pumping system for lifting formation fluids from onshore oil wells, and the identification of its working condition has an important influence on oil production. In this paper we proposed a diagnostic method for identifying the working condition of the submersible pumping system. Based on analyzing the working principle of the pumping unit and the pump structure, different characteristics in loading and unloading processes of the submersible linear motor were obtained at different working conditions. The characteristic quantities were extracted from operation data of the submersible linear motor. A diagnostic model based on the support vector machine （SVM） method was proposed for identifying the working condition of the submersible pumping unit, where the inputs of the SVM classifier were the characteristic quantities. The performance and the misjudgment rate of this method were analyzed and validated by the data acquired from an experimental simulation platform. The model proposed had an excellent performance in failure diagnosis of the submersible pumping system. The SVM classifier had higher diagnostic accuracy than the learning vector quantization （LVQ） classifier.
文摘A transient multiphase CFD （computational fluid dynamics） model was set up to investigate the main causes which lead to cavitation in PD （positive displacement） reciprocating pumps. Many authors agree on distinguishing two different types of cavitation affecting PD pumps： flow induced cavitation and cavitation due to expansion. The flow induced cavitation affects the zones of high fluid velocity and consequent low static pressure e.g. the valve-seat volume gap while the cavitation due to expansion can be detected in zones where the decompression effects are important e.g. in the vicinity of the plunger. This second factor is a distinctive feature of PD pumps since other devices such as centrifugal pumps are only affected by the flow induced type. Unlike what has been published in the technical literature to date, where analysis of positive displacement pumps are based exclusively on experimental or analytic methods, the work presented in this paper is based entirely on a CFD approach, it discusses the appearance and the dynamics of these two phenomena throughout an entire pumping cycle pointing out the potential of CFD techniques in studying the causes of cavitation and assessing the consequent loss of performance in positive displacement pumps.
文摘An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciprocating pumps discussed are the piston and plunger types. Rotary pumps addressed are gear( external and internal),vane,lobe,screw,and liquid ring pumps. To put the relative pump sizes in perspective,attention is fixed on the rotors or reciprocating elements of PD pumps,just as impellers indicate the sizes of rotodynamic pumps. The size of a PD pump is found from a dimensionless combination of displacement flow rate,rotative speed and diameter. The flow rate,head( or pressure rise) and power are related through the component efficiencies. The cavitation coefficient,often close to unity,connects the rotor tip speed or piston speed with the required NPSH,which can also be affected by the pressure rise of the pump due to leakage across the internal clearances. Operational effects due to cavitation,ingestion of gas or abrasives,and viscous and non-Newtonian fluids are discussed.
文摘The use of non-steroidal anti-inflammatory drugs(NSAIDs) is widespread worldwide thanks to their analgesic, anti-inflammatory and antipyretic effects. However, even more attention is placed upon the recurrence of digestive system complications in the course of their use. Recent data suggests that the complications of the lower gastro-intestinal tract may be as frequent and severe as those of the upper tract. NSAIDs enteropathy is due to enterohepatic recycling of the drugs resulting in a prolonged and repeated exposure of the intestinal mucosa to the compound and its metabolites. Thus leading to so-called topical effects, which, in turn, lead to an impairment of the intestinal barrier. This process determines bacterial translocation and toxic substances of intestinal origin in the portal circulation, leading to an endotoxaemia. This condition could determine a liver inflammatory response and might promote the development of nonalcoholic steatohepatitis, mostly in patients with risk factors such as obesity, metabolic syndrome and a high fat diet, which may induce a small intestinal bacterial overgrowth and dysbiosis. This alteration of gut microbiota may contribute to nonalcoholic fatty liver disease and its related disorders in two ways: firstly causing a malfunction of the tight junctions that play a critical role in the increase of intestinal permeability, and then secondly leading to the development of insulin resistance, body weight gain, lipogenesis, fibrogenesis and hepatic oxidative stress.
基金This work was supported by the National Natural Science Foundation of China （No.20771079） and the Natural Science Foundation of Education Department of Jiangsu Province （No.07KJB150126）.
文摘BaCe0.8Pr0.2O3-α ceramic was synthesized by high temperature solid-state reaction. The structural characteristics and the phase purity of the crystal were determined using powder X-ray diffraction analysis. By using the methods of AC impedance spectroscopy, gas concentration cell and electrochemical pumping of hydrogen, the conductivity and ionic transport number of BaCe0.8Pr0.2O3-α were measured, and the electrical conduction behavior of the material was investigated in different gases in the temperature range of 500-900℃. The results indicate that the material was of a single perovskite-type orthorhombic phase. From 500℃ to 900 ℃, electronic-hole conduction was dominant in dry and wet oxygen, air or nitrogen, and the total conductivity of the material increased slightly with increasing oxygen partial pressure in the oxygen partial pressure range studied. Ionic conduction was dominant in wet hydrogen, and the total conductivity was about one or two orders of magnitude higher than that in hydrogen-free atmosphere （oxygen, air or nitrogen）
文摘Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic damage. So we use on pump beating heart technique to supplement off-pump CABG. Methods Based on 860 off-pump CABG cases between Aug 1998 to Aug 2000. From Aug 1999 to Aug 2000, 46 CABG cases were performed with on pump beating heart technique at Mani-pal Hospital Heart Foundation, Bangalore, India. All surgeries were performed through a median sternotomy. Exposure techniques were tailored to individual vessels and cardiac regions and local immobilization was performed with octopus. Vascular control was achieved with occluders and shunts. Total cardiopulmonary bypass (CPB) was established before or during CABG and normolthemia was used. Results Among 46 on -pump beating heart CABG patients, 26 patients used CPB before or during OP - CABG because of unstable hemodynamics and electric instability , 7 had very deep intramyocardial left anterior descending arteries, 5 patients had poor LV function (LVEF < 30 % ), 8 patients had cardiomegaly. The average number of grafts was 3.5. No operative mortality. Three patients had postoperative myocardial infarction. Anesthetic time 4. 5±1. 2 hours, extubation time 10±2. 5 hours, blood lost 680±230 mL, blood requirement 540±150 mL, preoperative LVEF 50. 3±13 % , postoperative LVEF 64. 1±14 %, ICU stay 1. 5±0. 5 days, hospi- tal stay 9.2±1.8 days. Conclusion Complete coronary revascularization with on pump beating heart is a supplement for off - pump CABG when it is not feasible. It eliminates intraoperative globe myocardial ischemia and avoids transient myocardial injury during cardioplegic arrest and myocardial reperfusion.
