In order to solve the problem of spontaneous combustion in goaf, it is necessary to control the air leakage in the goaf to keep the internal and external pressure balance. Taking a specific project as an example, this...In order to solve the problem of spontaneous combustion in goaf, it is necessary to control the air leakage in the goaf to keep the internal and external pressure balance. Taking a specific project as an example, this paper briefly analyzes the factors affecting air leakage, discusses the working principle of pressure equalizing fire prevention, sorts out the technical innovation points of this project, and analyzes the actual benefits.展开更多
In this paper, a high stiffness rectangular floatation cushion with a variable-section pressure equalizing groove of an elastic membrane for a pneumato-static slideway is presented and designed in order to increase st...In this paper, a high stiffness rectangular floatation cushion with a variable-section pressure equalizing groove of an elastic membrane for a pneumato-static slideway is presented and designed in order to increase stiffness of the floatation cushion. Gas film pressure distribution and carrying capacity of the floatation cushion are studied through theoretical analysis and by using the overlapping stitching technique. The carrying capacity and stiffness were obtained by using the coupling procedure of the gas lubrication governing equation and elastic deformation of the membrane governing equation. The results of theoretical calculations can obtain a conclusion that the effect of the gas pressure makes the annular elastic membrane elastically deform that brings about changes of throttling area and pressure groove depth of the floatation cushion. It makes carrying capacity and stiffness of the new style floata- tion cushion markedly improve over the conventional flotation cushion. The new floatation cushion has a wider ap- plication and popularization of space. Key words： floatation cushion; variable-section pressure equalizing groove;stiffness展开更多
Chronic obstructive pulmonary disease(COPD)is a leading cause of disability and death of adults in the USA and worldwide.While environmental factors such as smoking and air pollution are major contributors to COPD,ped...Chronic obstructive pulmonary disease(COPD)is a leading cause of disability and death of adults in the USA and worldwide.While environmental factors such as smoking and air pollution are major contributors to COPD,pediatric respiratory disease and more specifically early childhood wheezing are frequent predisposing factors.It is therefore possible that aggressive prevention and treatment of childhood respiratory illness may modify adult COPD risk.This article reviews some of the physiological factors that may explain the pediatric origins of childhood lung disease.One such factor is the"tracking"of normal lung function which occurs with growth.The maximal expiratory flow volume(MEFV)curve is an ideally suited tool to monitor tracking of airway function over the lifespan,as its relative effort independence makes it highly reliable.Study of the MEFV curve has demonstrated that individuals with similar lung volumes can have large differences in maximal flows,reflecting a disconnection between airway and lung growth("dysanapsis").Less than average airway size due to dysanaptic airway growth or airway remodeling may be independent risk factors for the development of COPD and the asthma/COPD overlap syndrome in adult life.There are intriguing early data suggesting that perhaps at least some of this risk is modifiable by improving asthma control with inhaled corticosteroids and minimizing asthma exacerbations.展开更多
文摘In order to solve the problem of spontaneous combustion in goaf, it is necessary to control the air leakage in the goaf to keep the internal and external pressure balance. Taking a specific project as an example, this paper briefly analyzes the factors affecting air leakage, discusses the working principle of pressure equalizing fire prevention, sorts out the technical innovation points of this project, and analyzes the actual benefits.
文摘In this paper, a high stiffness rectangular floatation cushion with a variable-section pressure equalizing groove of an elastic membrane for a pneumato-static slideway is presented and designed in order to increase stiffness of the floatation cushion. Gas film pressure distribution and carrying capacity of the floatation cushion are studied through theoretical analysis and by using the overlapping stitching technique. The carrying capacity and stiffness were obtained by using the coupling procedure of the gas lubrication governing equation and elastic deformation of the membrane governing equation. The results of theoretical calculations can obtain a conclusion that the effect of the gas pressure makes the annular elastic membrane elastically deform that brings about changes of throttling area and pressure groove depth of the floatation cushion. It makes carrying capacity and stiffness of the new style floata- tion cushion markedly improve over the conventional flotation cushion. The new floatation cushion has a wider ap- plication and popularization of space. Key words： floatation cushion; variable-section pressure equalizing groove;stiffness
文摘Chronic obstructive pulmonary disease(COPD)is a leading cause of disability and death of adults in the USA and worldwide.While environmental factors such as smoking and air pollution are major contributors to COPD,pediatric respiratory disease and more specifically early childhood wheezing are frequent predisposing factors.It is therefore possible that aggressive prevention and treatment of childhood respiratory illness may modify adult COPD risk.This article reviews some of the physiological factors that may explain the pediatric origins of childhood lung disease.One such factor is the"tracking"of normal lung function which occurs with growth.The maximal expiratory flow volume(MEFV)curve is an ideally suited tool to monitor tracking of airway function over the lifespan,as its relative effort independence makes it highly reliable.Study of the MEFV curve has demonstrated that individuals with similar lung volumes can have large differences in maximal flows,reflecting a disconnection between airway and lung growth("dysanapsis").Less than average airway size due to dysanaptic airway growth or airway remodeling may be independent risk factors for the development of COPD and the asthma/COPD overlap syndrome in adult life.There are intriguing early data suggesting that perhaps at least some of this risk is modifiable by improving asthma control with inhaled corticosteroids and minimizing asthma exacerbations.
