An electrohydrodynamic （EHD） method, which is based on glow discharge plasma, is presented for flow control in an S-shaped duct. The research subject is an expanding channel with a constant width and a rectangular c...An electrohydrodynamic （EHD） method, which is based on glow discharge plasma, is presented for flow control in an S-shaped duct. The research subject is an expanding channel with a constant width and a rectangular cross section. An equivalent divergence angle and basic function are introduced to build the three-dimensional model. Subsequently, the plasma physical models are simplified as the effects of electrical body force and work （done by the force） on the fluid near the wall. With the aid of FLUENT software, the source terms of momentum and energy are added to the Navier-Stokes equation. Finally, the original performance of three models （A, B and C） is studied, in which model A demonstrates better performance. Then EHD control based on model A is discussed. The results show that the EHD method is an effective way of reducing flow loss and improving uniformity at the duct exit. The innovation in this study is the assessment of the EHD control effect on the flow in an S-shaped duct. Both the parametric modeling of the S-shaped duct and the simplified models of plasma provide valuable information for future research on aircraft inlet ducts.展开更多
BACKGROUND: Acute pancreatitis is an acute inflammatory process of the pancreas that frequently involves peripancreatic tissues and at times remote organ systems. For a long time, the etiology and pathogenesis of acut...BACKGROUND: Acute pancreatitis is an acute inflammatory process of the pancreas that frequently involves peripancreatic tissues and at times remote organ systems. For a long time, the etiology and pathogenesis of acute pancreatitis has been intensively investigated worldwide, but the pathogenetic theories are controversial. The integrity of the pancreatic duct-acinar system might play an important role in the pathogenesis of this disease. DATA SOURCES: Web of Science and PubMed databases were searched for published studies (between January 1966 and June 2009) to identify relevant articles using the keywords 'acinar hyperstimulation', 'pathogenesis', 'acute pancreatitis', 'pancreatic duct-acinar system', and 'pancreatic duct pressure'. Most of the relevant articles were reviewed. RESULTS: From critical reading of the relevant articles, we found that the underlying mechanisms involved in the pathogenesis of acute pancreatitis are still under debate and ill-understood. On the basis of the relevant studies, we propose a hypothesis for the pathogenesis of acute pancreatitis, in which the integrity of the pancreatic duct-acinar system plays an essential role in the onset and progression of various forms of the disease. CONCLUSIONS: In our hypothesis, pancreatic duct obstruction and hyperstimulation of the exocrine pancreas are preconditions for the onset of acute pancreatitis; under the common conditions of pancreatic duct obstruction and acinar hyperstimulation, acute pancreatitis arises and develops. This may be an important common pathophysiological mechanism causing various forms of acute pancreatitis. (Hepntobiliary Pancreat Dis Int 2010; 9: 242-247)展开更多
The fine structure of resin secreting cells of the conical resin ducts in stem of Pinus sylvestris Carr.was studied with the help of high pressure freezing and freeze-substitution techniques. An unprecedented modeof r...The fine structure of resin secreting cells of the conical resin ducts in stem of Pinus sylvestris Carr.was studied with the help of high pressure freezing and freeze-substitution techniques. An unprecedented modeof resin elimination was observed. It seems that the hydrolase-contained Golgi vesicles take part in the dissolution of plasmalemma, and a passage is formed, through which resin material may quickly pass outside of theprotoplast. Then, the ruptured plasmalemma was repaired by some vesicles, possibly derived from Golgi bodies.展开更多
The duct static pressure reset (DSPR) control method is a popular modern control method widely applied to variable air volume (VAV) systems of commercial buildings. In this paper, a VAV system simulation program was u...The duct static pressure reset (DSPR) control method is a popular modern control method widely applied to variable air volume (VAV) systems of commercial buildings. In this paper, a VAV system simulation program was used to predict the system performance and zone air temperature of two kinds of layouts that were applied to a typical floor of an existing building office in Hong Kong. The position where the static pressure sensor was placed should affect the zones temperature and energy consumption. The comparison of predictions of the two kinds of layouts indicates that with the same DSPR control method the layout of the air duct might influence the fan control result and energy savings.展开更多
In order to cut down excessive experiments, acoustic response of the different fan ducted discharge (equipment) was studied based on numerical method. The sound pressure level(SPL) in each component of a duct-plenum-r...In order to cut down excessive experiments, acoustic response of the different fan ducted discharge (equipment) was studied based on numerical method. The sound pressure level(SPL) in each component of a duct-plenum-reverberant room model was drawn and SPL deviation was analyzed. The trends of the curves were explained by the diffracti on and end reflection at the duct discharge. Models with different room dimensions, duct lengths, duct cross sections, duct locations and duct elbow were constructed, and their response was analyzed and compared. The results show that the SPL curves are smooth in the duct discharge cross section, but seriously fluctuant in the reverberant room; SPL in the duct discharge is only sensitive to duct dimensions, while that of the reverberant room is regularly influenced by all the dimension and arrangement factors. Small room and short duct help to increase room SPL. Elbow has an indistinct influence on all the components’ sound field. Finally, suggestion to reduce the deviation of experiment results was proposed.展开更多
文摘An electrohydrodynamic （EHD） method, which is based on glow discharge plasma, is presented for flow control in an S-shaped duct. The research subject is an expanding channel with a constant width and a rectangular cross section. An equivalent divergence angle and basic function are introduced to build the three-dimensional model. Subsequently, the plasma physical models are simplified as the effects of electrical body force and work （done by the force） on the fluid near the wall. With the aid of FLUENT software, the source terms of momentum and energy are added to the Navier-Stokes equation. Finally, the original performance of three models （A, B and C） is studied, in which model A demonstrates better performance. Then EHD control based on model A is discussed. The results show that the EHD method is an effective way of reducing flow loss and improving uniformity at the duct exit. The innovation in this study is the assessment of the EHD control effect on the flow in an S-shaped duct. Both the parametric modeling of the S-shaped duct and the simplified models of plasma provide valuable information for future research on aircraft inlet ducts.
基金supported by a grant from the National Natural Science Foundation of China(No.30830100)
文摘BACKGROUND: Acute pancreatitis is an acute inflammatory process of the pancreas that frequently involves peripancreatic tissues and at times remote organ systems. For a long time, the etiology and pathogenesis of acute pancreatitis has been intensively investigated worldwide, but the pathogenetic theories are controversial. The integrity of the pancreatic duct-acinar system might play an important role in the pathogenesis of this disease. DATA SOURCES: Web of Science and PubMed databases were searched for published studies (between January 1966 and June 2009) to identify relevant articles using the keywords 'acinar hyperstimulation', 'pathogenesis', 'acute pancreatitis', 'pancreatic duct-acinar system', and 'pancreatic duct pressure'. Most of the relevant articles were reviewed. RESULTS: From critical reading of the relevant articles, we found that the underlying mechanisms involved in the pathogenesis of acute pancreatitis are still under debate and ill-understood. On the basis of the relevant studies, we propose a hypothesis for the pathogenesis of acute pancreatitis, in which the integrity of the pancreatic duct-acinar system plays an essential role in the onset and progression of various forms of the disease. CONCLUSIONS: In our hypothesis, pancreatic duct obstruction and hyperstimulation of the exocrine pancreas are preconditions for the onset of acute pancreatitis; under the common conditions of pancreatic duct obstruction and acinar hyperstimulation, acute pancreatitis arises and develops. This may be an important common pathophysiological mechanism causing various forms of acute pancreatitis. (Hepntobiliary Pancreat Dis Int 2010; 9: 242-247)
文摘The fine structure of resin secreting cells of the conical resin ducts in stem of Pinus sylvestris Carr.was studied with the help of high pressure freezing and freeze-substitution techniques. An unprecedented modeof resin elimination was observed. It seems that the hydrolase-contained Golgi vesicles take part in the dissolution of plasmalemma, and a passage is formed, through which resin material may quickly pass outside of theprotoplast. Then, the ruptured plasmalemma was repaired by some vesicles, possibly derived from Golgi bodies.
文摘The duct static pressure reset (DSPR) control method is a popular modern control method widely applied to variable air volume (VAV) systems of commercial buildings. In this paper, a VAV system simulation program was used to predict the system performance and zone air temperature of two kinds of layouts that were applied to a typical floor of an existing building office in Hong Kong. The position where the static pressure sensor was placed should affect the zones temperature and energy consumption. The comparison of predictions of the two kinds of layouts indicates that with the same DSPR control method the layout of the air duct might influence the fan control result and energy savings.
文摘In order to cut down excessive experiments, acoustic response of the different fan ducted discharge (equipment) was studied based on numerical method. The sound pressure level(SPL) in each component of a duct-plenum-reverberant room model was drawn and SPL deviation was analyzed. The trends of the curves were explained by the diffracti on and end reflection at the duct discharge. Models with different room dimensions, duct lengths, duct cross sections, duct locations and duct elbow were constructed, and their response was analyzed and compared. The results show that the SPL curves are smooth in the duct discharge cross section, but seriously fluctuant in the reverberant room; SPL in the duct discharge is only sensitive to duct dimensions, while that of the reverberant room is regularly influenced by all the dimension and arrangement factors. Small room and short duct help to increase room SPL. Elbow has an indistinct influence on all the components’ sound field. Finally, suggestion to reduce the deviation of experiment results was proposed.
