The practice of ventilation is continually evolving with new technological advances developed in the mining industry.In recent years the advances in diesel engine technologies,ventilation modeling software,and ventila...The practice of ventilation is continually evolving with new technological advances developed in the mining industry.In recent years the advances in diesel engine technologies,ventilation modeling software,and ventilation management capacities have redefined the historical methods used to evaluate systems.The advances re-evaluate previous methods used to calculate the airflow requirements for the dilution of diesel exhaust fumes.Modeling software has become an integral part of planning and developing ventilation systems in partnership with graphical mine design software packages to generate realistic representations of the mine.Significant advances in ventilation control strategies through remote sensors and monitoring capabilities have been developed to results in cost savings.Though there has been much advancement in mine ventilation technology,the practices and basic ventilation principals enacted through the ventilation engineer cannot be placated with technological advances only.展开更多
In large mines,single fan is usually not enough to ventilate all the working areas.Single mine-fan approach cannot be directly applied to multiple-fan networks because the present of multiple pressures and air quantit...In large mines,single fan is usually not enough to ventilate all the working areas.Single mine-fan approach cannot be directly applied to multiple-fan networks because the present of multiple pressures and air quantities associated with each fan in the network.Accordingly,each fan in a multiple-fan system has its own mine characteristic curve,or a subsystem curve.Under some consideration,the conventional concept of a mine characteristic curve of a single-fan system can be directly extended to that of a particular fan within a multiple-fan system.In this paper the mutual effect of the fans on each other and their effect on the stability of the ventilation network were investigated by Hardy Cross algorithm combined with a switching-parameters technique.To show the validity and reliability of this algorithm,the stability of the ventilation system of Abu-Tartur Mine(one of the largest underground mine in Egypt)has been studied.展开更多
To compare effect of high-frequency oscillation ventilation (HFOV) and conventional mandatory ventilation (CMV) on lung injury development in rabbit with acute respiratory distress syndrome ( ARDS). Methods Anim...To compare effect of high-frequency oscillation ventilation (HFOV) and conventional mandatory ventilation (CMV) on lung injury development in rabbit with acute respiratory distress syndrome ( ARDS). Methods Animals that underwent saline lung lavage to produce lung injury were randomized to one of the two treatment groups ( HFOV or CMV, n =6). PaCO2 was maintained between 35 -45mmHg and arterial oxygen saturation ( SaO2 ) was maintain 〉 88% by adjusting corresponding ventilator parameters. Ventilation period was 6h. Lung fluids were aspirated before and at the end of ventilation for cell analysis. Then the animals were euthanized, lung tissue was removed for wet/dry weight measurement, light and electron microscopic examination. Besults The difference of artery blood gas analyses(pH, PaO2, PaCO2 ) between HFOV and CMV was insignificant. The difference between HFOV and CMV in cytological examination of lung fluids, wet/dry weight measurement was also insignificant. But compared with CMV, HFOV not only reduced the area of lung injury, but also reduced lung injury score in light and electron microscopic examination. Conclusion When same artery blood gas analysis was obtained, HFOV significantly reduced lung injury development in ARDS animal than CMV. As a lung protection strategy, HFOV can be used in the treatment of ARDS.展开更多
The effectiveness of line brattice(LB) ventilation system depends on the associated system variables.However, the effect of these variables on the air flow rates close to the face of the heading is not extensively stu...The effectiveness of line brattice(LB) ventilation system depends on the associated system variables.However, the effect of these variables on the air flow rates close to the face of the heading is not extensively studied. In this paper, the effect of the LB length in relation to the LB-wall distance on the air flow rate reaching the face is analysed. Scenarios were developed using four LB lengths, two LB-wall distances and two heading depths. These scenarios were simulated with a validated CFD model. The air flow rates and patterns at various locations inside the heading were analysed. This helped to find the minimum LB-face distance that should be maintained for each LB-wall distance to maximise the air flow rate at the face. The minimum length when used will improve ventilation and reduce energy cost.展开更多
Background Early withdraw from invasive mechanical ventilation (MV) followed by noninvasive MV is a new strategy for changing modes of treatment. This study was conducted to estimate the feasibility and the efficacy...Background Early withdraw from invasive mechanical ventilation (MV) followed by noninvasive MV is a new strategy for changing modes of treatment. This study was conducted to estimate the feasibility and the efficacy of early extubation and sequential noninvasive MV commenced at beginning of pulmonary infection control window in patients with exacerbated hypercapnic respiratory failure caused by chronic obstructive pulmonary diseases ( C OPD ). Methods A prospective, randomized controlled study was conducted in eleven teaching hospitals' respiratory or medical intensive care units in China. Ninety intubated COPD patients with severe hypercapnic respiratory failure triggered by pulmonary infection (pneumonia or purulent bronchitis) were involved in the study. When the pulmonary infection had been controlled by antibiotics and comprehensive therapy, the “pulmonary infection control window (PIC window)” has been reached. Each case was randomly assigned to study group (extubation and noninvasive MV via facial mask immediately) or control group ( invasive MV was received continuously after PIC window by using conventional weaning technique). Results Study group (n = 47 ) and control group (n = 43 ) had similar clinical characteristics initially and at the time of PIC window. Compared with control group, study group had shorter duration of invasive MV [ (6. 4±4. 4) days vs ( 11.3±6. 2) days, P =0. 0001, lower rate of ventilator associated pneumonia (VAP) (3/47 vs 12/43, P=0.014), fewer days in ICU [(12 +8) days vs 16 + 11) days, P =0.047] and lower hospital mortality ( 1/47 vs 7/43, P =0. 025). Conclusions In COPD patients requiring intubation and lnvasive MV for hypercapnic respiratory failure, which is exacerbated by pulmonary infection, early extubation followed by noninvasive MV initiated at the start of PIC window may decrease significantly the duration of invasive MV, the risk of VAP and hospital mortality.展开更多
文摘The practice of ventilation is continually evolving with new technological advances developed in the mining industry.In recent years the advances in diesel engine technologies,ventilation modeling software,and ventilation management capacities have redefined the historical methods used to evaluate systems.The advances re-evaluate previous methods used to calculate the airflow requirements for the dilution of diesel exhaust fumes.Modeling software has become an integral part of planning and developing ventilation systems in partnership with graphical mine design software packages to generate realistic representations of the mine.Significant advances in ventilation control strategies through remote sensors and monitoring capabilities have been developed to results in cost savings.Though there has been much advancement in mine ventilation technology,the practices and basic ventilation principals enacted through the ventilation engineer cannot be placated with technological advances only.
文摘In large mines,single fan is usually not enough to ventilate all the working areas.Single mine-fan approach cannot be directly applied to multiple-fan networks because the present of multiple pressures and air quantities associated with each fan in the network.Accordingly,each fan in a multiple-fan system has its own mine characteristic curve,or a subsystem curve.Under some consideration,the conventional concept of a mine characteristic curve of a single-fan system can be directly extended to that of a particular fan within a multiple-fan system.In this paper the mutual effect of the fans on each other and their effect on the stability of the ventilation network were investigated by Hardy Cross algorithm combined with a switching-parameters technique.To show the validity and reliability of this algorithm,the stability of the ventilation system of Abu-Tartur Mine(one of the largest underground mine in Egypt)has been studied.
文摘To compare effect of high-frequency oscillation ventilation (HFOV) and conventional mandatory ventilation (CMV) on lung injury development in rabbit with acute respiratory distress syndrome ( ARDS). Methods Animals that underwent saline lung lavage to produce lung injury were randomized to one of the two treatment groups ( HFOV or CMV, n =6). PaCO2 was maintained between 35 -45mmHg and arterial oxygen saturation ( SaO2 ) was maintain 〉 88% by adjusting corresponding ventilator parameters. Ventilation period was 6h. Lung fluids were aspirated before and at the end of ventilation for cell analysis. Then the animals were euthanized, lung tissue was removed for wet/dry weight measurement, light and electron microscopic examination. Besults The difference of artery blood gas analyses(pH, PaO2, PaCO2 ) between HFOV and CMV was insignificant. The difference between HFOV and CMV in cytological examination of lung fluids, wet/dry weight measurement was also insignificant. But compared with CMV, HFOV not only reduced the area of lung injury, but also reduced lung injury score in light and electron microscopic examination. Conclusion When same artery blood gas analysis was obtained, HFOV significantly reduced lung injury development in ARDS animal than CMV. As a lung protection strategy, HFOV can be used in the treatment of ARDS.
基金the financial assistance required to purchase the high performance PC and the CFD software
文摘The effectiveness of line brattice(LB) ventilation system depends on the associated system variables.However, the effect of these variables on the air flow rates close to the face of the heading is not extensively studied. In this paper, the effect of the LB length in relation to the LB-wall distance on the air flow rate reaching the face is analysed. Scenarios were developed using four LB lengths, two LB-wall distances and two heading depths. These scenarios were simulated with a validated CFD model. The air flow rates and patterns at various locations inside the heading were analysed. This helped to find the minimum LB-face distance that should be maintained for each LB-wall distance to maximise the air flow rate at the face. The minimum length when used will improve ventilation and reduce energy cost.
文摘Background Early withdraw from invasive mechanical ventilation (MV) followed by noninvasive MV is a new strategy for changing modes of treatment. This study was conducted to estimate the feasibility and the efficacy of early extubation and sequential noninvasive MV commenced at beginning of pulmonary infection control window in patients with exacerbated hypercapnic respiratory failure caused by chronic obstructive pulmonary diseases ( C OPD ). Methods A prospective, randomized controlled study was conducted in eleven teaching hospitals' respiratory or medical intensive care units in China. Ninety intubated COPD patients with severe hypercapnic respiratory failure triggered by pulmonary infection (pneumonia or purulent bronchitis) were involved in the study. When the pulmonary infection had been controlled by antibiotics and comprehensive therapy, the “pulmonary infection control window (PIC window)” has been reached. Each case was randomly assigned to study group (extubation and noninvasive MV via facial mask immediately) or control group ( invasive MV was received continuously after PIC window by using conventional weaning technique). Results Study group (n = 47 ) and control group (n = 43 ) had similar clinical characteristics initially and at the time of PIC window. Compared with control group, study group had shorter duration of invasive MV [ (6. 4±4. 4) days vs ( 11.3±6. 2) days, P =0. 0001, lower rate of ventilator associated pneumonia (VAP) (3/47 vs 12/43, P=0.014), fewer days in ICU [(12 +8) days vs 16 + 11) days, P =0.047] and lower hospital mortality ( 1/47 vs 7/43, P =0. 025). Conclusions In COPD patients requiring intubation and lnvasive MV for hypercapnic respiratory failure, which is exacerbated by pulmonary infection, early extubation followed by noninvasive MV initiated at the start of PIC window may decrease significantly the duration of invasive MV, the risk of VAP and hospital mortality.