A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters;roughness of the airways and the friction factor. The...A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters;roughness of the airways and the friction factor. The 32 branch points (<em>i.e.</em> a-ag) that stand for ventilation circuit have been selected. Data collected includes, length and width of airways, air velocity;air density, and roughness of the airways which were used to determine coefficient of frictions, friction factors and airway resistances. A ventilation model was developed. In order to improve the current ventilation model, airways resistance of the mine was determined and simulated in a modified model using VentSim<sup>TM</sup> software. An average total airways resistance of 0.32027 Ns<sup>2</sup>/m<sup>8</sup> has been achieved for Rosh Pinah mine. It should be pointed out that, as the mine advances its production faces deeper, this value would increases suddenly. Simulation revealed that as much as 34.4 m<sup>3</sup>/s of air can be received at the production faces, compared to the measured received amount of 19.3 m<sup>3</sup>/s. Therefore, volumetric efficiency of the mine was improved from 29.3% to 68.3%. It was also noticed that after importing the resistance values into the model together with other parameters, the model was greatly improved and no cause for concern.展开更多
A computational fluid dynamics （CFD） approach is used to study the respiratory airflow dynamics within a human upper airway. The airway model which consists of the airway from nasal cavity, pharynx, larynx and trach...A computational fluid dynamics （CFD） approach is used to study the respiratory airflow dynamics within a human upper airway. The airway model which consists of the airway from nasal cavity, pharynx, larynx and trachea to triple bifurcation is built based on the CT images of a healthy volunteer and the Weibel model. The flow character- istics of the whole upper airway are quantitatively described at any time level of respiratory cycle. Simulation results of respiratory flow show good agreement with the clinical mea- sures, experimental and computational results in the litera- ture. The air mainly passes through the floor of the nasal cavity in the common, middle and inferior nasal meatus. The higher airway resistance and wall shear stresses are distrib- uted on the posterior nasal valve. Although the airways of pharynx, larynx and bronchi experience low shear stresses, it is notable that relatively high shear stresses are distrib- uted on the wall of epiglottis and bronchial bifurcations. Besides, two-dimensional fluid-structure interaction models of normal and abnormal airways are built to discuss the flow-induced deformation in various anatomy models. The result shows that the wall deformation in normal airway is relatively small.展开更多
OBJECTIVE: To investigate bronchial responsiveness to acetylcholine in allergic airway inflammation of SD rats. METHODS: SD rats were immunized and challenged by chicken ovalbumin (OVA). Airway responsiveness, acetylc...OBJECTIVE: To investigate bronchial responsiveness to acetylcholine in allergic airway inflammation of SD rats. METHODS: SD rats were immunized and challenged by chicken ovalbumin (OVA). Airway responsiveness, acetylcholine (Ach) provocation concentration needed to increase baseline airway resistance by 200% (PC(200)) were measured. RESULTS: The value of baseline airway resistance in asthma group was significantly higher than that in control group (2.282 +/- 0.128 vs 3.193 +/- 0.239; P展开更多
文摘A quantitative technique was conducted at Rosh Pinah Zinc mine, Namibia with its main purpose to determine airways resistance which is a function of the parameters;roughness of the airways and the friction factor. The 32 branch points (<em>i.e.</em> a-ag) that stand for ventilation circuit have been selected. Data collected includes, length and width of airways, air velocity;air density, and roughness of the airways which were used to determine coefficient of frictions, friction factors and airway resistances. A ventilation model was developed. In order to improve the current ventilation model, airways resistance of the mine was determined and simulated in a modified model using VentSim<sup>TM</sup> software. An average total airways resistance of 0.32027 Ns<sup>2</sup>/m<sup>8</sup> has been achieved for Rosh Pinah mine. It should be pointed out that, as the mine advances its production faces deeper, this value would increases suddenly. Simulation revealed that as much as 34.4 m<sup>3</sup>/s of air can be received at the production faces, compared to the measured received amount of 19.3 m<sup>3</sup>/s. Therefore, volumetric efficiency of the mine was improved from 29.3% to 68.3%. It was also noticed that after importing the resistance values into the model together with other parameters, the model was greatly improved and no cause for concern.
基金supported by the National Natural Science Foundation of China (10472025 10672036+1 种基金 10872043)Natural Science Foundation of Liaoning Province, China (20032109).
文摘A computational fluid dynamics （CFD） approach is used to study the respiratory airflow dynamics within a human upper airway. The airway model which consists of the airway from nasal cavity, pharynx, larynx and trachea to triple bifurcation is built based on the CT images of a healthy volunteer and the Weibel model. The flow character- istics of the whole upper airway are quantitatively described at any time level of respiratory cycle. Simulation results of respiratory flow show good agreement with the clinical mea- sures, experimental and computational results in the litera- ture. The air mainly passes through the floor of the nasal cavity in the common, middle and inferior nasal meatus. The higher airway resistance and wall shear stresses are distrib- uted on the posterior nasal valve. Although the airways of pharynx, larynx and bronchi experience low shear stresses, it is notable that relatively high shear stresses are distrib- uted on the wall of epiglottis and bronchial bifurcations. Besides, two-dimensional fluid-structure interaction models of normal and abnormal airways are built to discuss the flow-induced deformation in various anatomy models. The result shows that the wall deformation in normal airway is relatively small.
文摘OBJECTIVE: To investigate bronchial responsiveness to acetylcholine in allergic airway inflammation of SD rats. METHODS: SD rats were immunized and challenged by chicken ovalbumin (OVA). Airway responsiveness, acetylcholine (Ach) provocation concentration needed to increase baseline airway resistance by 200% (PC(200)) were measured. RESULTS: The value of baseline airway resistance in asthma group was significantly higher than that in control group (2.282 +/- 0.128 vs 3.193 +/- 0.239; P
