Heat Recovery Ventilators(HRVs)are essential for improving indoor air quality(IAQ)and reducing energy consumption in residential buildings situated in cold climates.This study considers the efficiency and performance ...Heat Recovery Ventilators(HRVs)are essential for improving indoor air quality(IAQ)and reducing energy consumption in residential buildings situated in cold climates.This study considers the efficiency and performance optimization of HRVs under cold climatic conditions,where conventional ventilation systems increase heat loss.A comprehensive numerical model was developed using COMSOL Multiphysics,integrating fluid dynamics,heat transfer,and solid mechanics to evaluate the thermal efficiency and structural integrity of an HRV system.The methodology employed a detailed geometry with tetrahedral elements,temperature-dependent material properties,and coupled governing equations solved under Tehran-specific boundary conditions.A multi-objective optimization was implemented in the framework of the Nelder-Mead simplex algorithm,targeting the maximization of the average outlet temperature and minimization of the maximum von Mises thermal stress,with inlet flow velocity as the design variable(range:0.5–1.2m/s).Results indicate an optimal velocity of 0.51563 m/s,achieving an average outlet temperature of 289.44 K and maximum von Mises stress of 221 MPa,validated through mesh independence and detailed contour analyses of temperature,velocity,and stress distributions.展开更多
Hard coal is an important source of energy worldwide.Owing to the imperfections of excavation technology,most run-of-mine coals must be processed before they can be utilised as fuel.In this study,tests on the dry sepa...Hard coal is an important source of energy worldwide.Owing to the imperfections of excavation technology,most run-of-mine coals must be processed before they can be utilised as fuel.In this study,tests on the dry separation process were performed with numerous different raw hard coal and coal waste material samples,using a newly designed and constructed negative-pressure pneumatic separator(NPPS).The experiments revealed the effects of the feed-material properties and material processing conditions.These experiments were preceded by additional tests for evaluating the influence of each device operating parameter on the process,to determine the optimal method of supplying the feed material.The calorific value of the processed materials was improved by 5%–40%,while a minimal output yield of products(60%–70%)was maintained.The trials indicated that in coal material processing,the developed NPPS can be used for not only raw coal enrichment but also coal recovery from materials stored at coal-waste dumps.The main advantages of the device are its mobility,low material processing cost,and lack of water consumption during operation.展开更多
Considering four different climate zones in China, an investigation on the choice of heat recovery ventilator for the buildings with little moisture emissions is carried out. The annual composition of energy consumpti...Considering four different climate zones in China, an investigation on the choice of heat recovery ventilator for the buildings with little moisture emissions is carried out. The annual composition of energy consumption of air intake for per unitary air ventilation flow rate is evaluated by employing the testing data of climatic parameters in eight selected cities. The analysis shows that the total heat recovery is suitable in a controlled ventilation system with air humidity controlled during heating period of all the climates. For the building without air humidity controlled in winter, the sensible heat recovery ventilators can be used in severe cold and cold regions, and total heat recovery systems are more suitable for energy saving in hot summer and cold winter and hot summer and warm winter regions.展开更多
A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source ...A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source was found to be the dynamic noise at the outlet of the diffuser. The frequency of its peak value was 250 Hz. A special brick with a resonant frequency of 250 Hz was designed to eliminate this noise. The diffusion of a lower frequency noise has been successfully controlled by the installation of a noise-eliminating tower above the diffuser outlet. The detection results show that the noise in the nearby residential area has been lowered to an average 55.3dB(A) in the daytime from 69.8dB(A) and to 48.4dB(A) at night from 65.8dB(A).展开更多
Safflower is one of the most important oil crops worldwide.To improve the efficiency and quality of harvesting soft safflower filaments,minimize filament damage by the blade,and ensure the integrity of the filaments,a...Safflower is one of the most important oil crops worldwide.To improve the efficiency and quality of harvesting soft safflower filaments,minimize filament damage by the blade,and ensure the integrity of the filaments,an end-effector with a rotary push-cut-type negative-pressure airflow was designed.The design of the rotary blade edge curve was based on Archimedean and logarithmic spirals.The effect of the Archimedean spiral on the pushing of the scattered filaments was investigated.The rotary-cutting force and speed of the logarithmic helix on the soft filaments were analyzed.The sliding cut angle and feed speed of the blade are the key factors governing filament removal and damage.A simulation model of the cutting chamber flow field was established for the change in airflow with the position and speed rotation of the blade,allowing analysis of the parameters of the negative-pressure airflow.Single-factor and Box-Behnken tests were performed with the sliding cut angle,blade feed speed,and negative-pressure airflow speed as influencing factors and filament removal,damage,and drop rate as indices.The response surface clarified the effects of various factors on these indices.Optimal parameters were a sliding cut angle of 32.20°,a blade feeding speed of 0.031 m/s,and a negative-pressure airflow speed of 4.57 m/s.The corresponding filament removal,damage,and drop rates were 93.47%,6.94%,and 4.33%,respectively.Optimization results showed that filament removal,damage,and drop rates were 93.50%,7.02%,and 4.43%,respectively.The harvesting process met the requirements of high efficiency and low damage.展开更多
Objective:To investigate the application effect of intelligent empowerment standardized airway management process in patients receiving mechanical ventilation.Methods:A retrospective analysis was conducted on the clin...Objective:To investigate the application effect of intelligent empowerment standardized airway management process in patients receiving mechanical ventilation.Methods:A retrospective analysis was conducted on the clinical data of 79 EICU inpatients who underwent tracheal intubation and mechanical ventilation treatment at our hospital from January 2023 to May 2025.The patients were divided into a control group(conventional airway management process,n=40)and a study group(intelligent empowerment standardized airway management process,n=39)based on the intervention protocols they received.Oral health scores,dental plaque index,oral odor,serum inflammatory markers[C-reactive protein(CRP),procalcitonin(PCT)],clinical pulmonary infection score(CPIS),as well as the incidence of ventilator-associated pneumonia(VAP),duration of mechanical ventilation,and length of stay in the EICU were assessed before and after treatment.Results:The baseline values of all indicators were consistent between the two groups before intervention(p>0.05).After corresponding interventions,both groups showed significant improvements in Beck oral health scores,dental plaque index,and oral odor,with more pronounced improvements observed in the study group(p<0.05).After the intervention,the research group showed a significant decrease in serum CRP and PCT levels,as well as CPIS scores(p<0.05).In contrast,the control group experienced an increase in these three indicators to a certain extent(p<0.05).Moreover,the incidence of ventilator-associated pneumonia(VAP),duration of mechanical ventilation,and length of stay in the EICU were all lower in the research group compared to the control group,while the nurse’s compliance rate with the protocol was higher in the research group(p<0.05).Conclusion:The standardized airway management protocol empowered by intelligent technology can significantly improve nursing compliance,benefit oral health status,reduce the risk of pulmonary infection and systemic inflammation levels,and promote rapid patient recovery,demonstrating considerable potential for widespread adoption.展开更多
Phrenic nerve stimulation(PNS)may preserve diaphragm activation and mitigate multiorgan injury during mechanical ventilation(MV);however,a minimal invasive rat model integrating PNS with MV is lacking.We established a...Phrenic nerve stimulation(PNS)may preserve diaphragm activation and mitigate multiorgan injury during mechanical ventilation(MV);however,a minimal invasive rat model integrating PNS with MV is lacking.We established an omohyoid muscle-based PNS rat model combined with MV.Bilateral nerves were exposed within 20±2 min by transection at the intermediate tendon of omohyoid muscle,minimizing trauma and bleeding.Threshold stimulation(0.6±0.2 mA)correlated with body weight.Ventilator-synchronized stimulation increased compound muscle action potentials by~30%,whereas histology confirmed intact nerve.Physiological parameters remained stable throughout ventilation.This model provides a safe and scalable platform for mechanistic and preclinical studies on PNS-mediated protection against MV-induced organ injury.展开更多
Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is sig...Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is significant controversy regarding its concurrent use with ACS owing to concerns of increased risk of intra-abdominal pressure(IAP).[1]We present a case of successful PPV application without adverse eff ects.展开更多
A recent study on the rapid imaging of pulmonary ventilation using hyperpolarized ^(129)Xe MRI has demonstrated the ability to achieve isotropic 3D ventilation imaging with a spatial resolution of 3×3×3mm^(3...A recent study on the rapid imaging of pulmonary ventilation using hyperpolarized ^(129)Xe MRI has demonstrated the ability to achieve isotropic 3D ventilation imaging with a spatial resolution of 3×3×3mm^(3) in humans,within an acquisition time of just 3.5 seconds(https://doi.org/10.1002/mrm.30120).展开更多
Prediction of weaning success from invasive mechanical ventilation remains a challenge in everyday clinical practice.Several prediction scores have been developed to guide success during spontaneous breathing trials t...Prediction of weaning success from invasive mechanical ventilation remains a challenge in everyday clinical practice.Several prediction scores have been developed to guide success during spontaneous breathing trials to help with weaning decisions.These scores aim to provide a structured framework to support clinical judgment.However,their effectiveness varies across patient populations,and their predictive accuracy remains inconsistent.In this review,we aim to identify the strengths and limitations of commonly used clinical prediction tools in assessing readiness for ventilator liberation.While scores such as the Rapid Shallow Breathing Index and the Integrative Weaning Index are widely adopted,their sensitivity and specificity often fall short in complex clinical settings.Factors such as underlying disease pathophysiology,patient characteristics,and clinician subjectivity impact score performance and reliability.Moreover,disparities in validation across diverse populations limit generalizability.With growing interest in artificial intelligence(AI)and machine learning,there is potential for enhanced prediction models that integrate multidimensional data and adapt to individual patient profiles.However,current AI approaches face challenges related to interpretability,bias,and ethical implementation.This paper underscores the need for more robust,individualized,and transparent prediction systems and advocates for careful integration of emerging technologies into clinical workflows to optimize weaning success and patient outcomes.展开更多
During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped wit...During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air ducts.In this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment simulation.In addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle tests.The results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other train.During train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching 3.2.The average mass flow falls below the rated mass flow for the converter.Compared to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,respectively.Compared to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,respectively.These findings provide valuable insights into the design and operation of high-speed trains.展开更多
BACKGROUND:In this study,we aimed to evaluate the impact of mechanical ventilator(MV)utilizaton during cardiopulmonary resuscitation(CPR)on out-of-hospital cardiac arrest(OHCA)patient clinical outcomes in the emergenc...BACKGROUND:In this study,we aimed to evaluate the impact of mechanical ventilator(MV)utilizaton during cardiopulmonary resuscitation(CPR)on out-of-hospital cardiac arrest(OHCA)patient clinical outcomes in the emergency department.METHODS:This single-centered,retrospective,case-control study analyzed electronic medical records.Patients aged>18 years with non-traumatic OHCA who were treated at an emergency medical center between January 2019 and December 2023 were included.These patients were accessed according to the ventilatory method used:MV ventilation(volume control,tidal volume 6-8 mL/kg,frequency 10 beat per minute,inspiratory time 1 s)and manual resuscitator bag valve(BV)ventilation.The primary outcome was the return of spontaneous circulation(ROSC).After 1:1 propensity score matching,the clinical outcomes were analyzed.RESULTS:A total of 649 patients were enrolled in this study.Before matching,the clinical outcomes and pneumothorax incidence did not differ between the MV and BV groups.After 1:1 matching between the two groups using propensity scores,522 patients(261 MV and 261 BV)were analyzed.Propensity score matching yielded an adequate balance(standardized mean difference<0.10)for all covariates.The estimated odds ratio(OR)for ROSC was 1.23(95%confidence interval[CI]:0.85-1.77;P=0.267),for survival at hospital admission was 1.02(95%CI:0.68-1.53;P=0.918),for survival at hospital discharge was 2.31(95%CI:1.10-5.20;P=0.033),and for good neurologic outcome was 2.56(95%CI:0.84-9.43;P=0.116).CONCLUSION:In patients with OHCA admitted to the emergency department,MV ventilation during CPR showed clinical outcomes similar to those of BV ventilation in most measures.However,survival at hospital discharge was significantly higher in the MV group,suggesting potential benefits of MV use in selected patients.展开更多
BACKGROUND There has been a growing interest in noninvasive ventilation(NIV)in comparison to invasive mechanical ventilation(IMV)as a standard of care for acute respiratory failure(ARF),especially in the post-covid er...BACKGROUND There has been a growing interest in noninvasive ventilation(NIV)in comparison to invasive mechanical ventilation(IMV)as a standard of care for acute respiratory failure(ARF),especially in the post-covid era,but direct head-to-head cost comparisons between the two modalities are not available in literature.AIM To compare the cost along with the clinical effectiveness of NIV in comparison to IMV in ARF.METHODS A prospective observational single-center case control study including adult patients with ARF(PaO2/FiO2 ratio<300)admitted from January 1,2024 to December 31,2024 in medical intensive care unit(ICU)of a tertiary care hospital requiring either NIV or invasive ventilation.NIV and IMV groups were compared based on average length of ICU and hospital stay,mortality,net cost of ICU treatment,need for intubation and tracheostomy.RESULTS A total of 319 patients were included in the study(197 in NIV,122 in IMV group).Statistically significant difference in length of ICU stay(NIV group:5±3.25 days,IMV group:9±2.6 days;P<0.05)and mortality rate was seen(11%NIV vs 34%IMV;P<0.01).On multivariate analyses,mortality showed a stronger association with IMV[odds ratio(OR)=7.73;95%CI:3.12-19.18]as compared to ICU stay(OR=2.73;95%CI:2.15-3.48).A total of 33 patients(17%)in NIV group required intubation of which 3 were tracheostomized,while 14 patients(11%)in IMV group needed tracheostomy.The net average cost of ICU stay was₹83902 in NIV group while in IMV group,the net ICU cost was₹476216.The average cost of ICU stay was five times higher with IMV.CONCLUSION NIV has potential economic and clinical benefits as compared to invasive ventilation in ARF.展开更多
Mechanical ventilation is a specialized oxygen therapy and life support technology with significant importance for critically ill patients. In fact, 40%–66% of patients in the intensive care unit(ICU) require mechani...Mechanical ventilation is a specialized oxygen therapy and life support technology with significant importance for critically ill patients. In fact, 40%–66% of patients in the intensive care unit(ICU) require mechanical ventilation.^([1,2]) However, the mechanical ventilation can lead to ventilatorassociated lung injury(VALI),^([3]) ultimately resulting in difficulties in weaning from mechanical ventilation,prolonged hospital stays, and even increased mortality.展开更多
Variable air volume systems are widely used in trains as they provide effective energy savings for air conditioning.However,the design phase is usually carried out at a certain fixed airflow,resulting in a difference ...Variable air volume systems are widely used in trains as they provide effective energy savings for air conditioning.However,the design phase is usually carried out at a certain fixed airflow,resulting in a difference between the expected and actual flow fields.In this study,we first analyzed the flow field characteristics at variable airflow rates under isothermal conditions,and subsequently established a correlation equation between the airflow and the flow field parameters.The results show that the airflow just entering the compartment conforms to the characteristics of an attached jet,and then,after converging in the middle,conforms to the characteristics of a free jet.The flow field characteristics are significantly correlated with the Reynolds number(Re)and are limited by the small space inside the vehicle.When Re≥2650,the axial velocities all conform to the classical u_(m)/u_(0)−(x/b)^(r) or u_(m)/u_(0)−(y/b)^(r) law,the sectional velocities conform to the exponential and Gaussian distributions,and the characteristic thicknesses of the jets conform to a linear distribution.Derivation shows that the entrainment suction flow rate is related mainly to the initial flow rate and the air opening width.The results of this study will inform the design of ventilation systems for high-speed trains.展开更多
With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ...With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ventilation pipes of different structures are investigated by experiments and numerical simulations.Furthermore,for the same structure,the effects of peak pressure and positive pressure time on the attenuation rate are discussed.It is found that the attenuation rate increases with the incident shock wave pressure,and the shock wave attenuation rate tends to reach its limiting value k for the same structure and reasonably short positive pressure time.Under the same conditions,the attenuation rate is calculated using the pressure of the shock wave as follows:diffusion chamber pipe,branch pipe and selfconsumption pipe;the attenuation rate per unit volume is calculated as follows:self-consumption pipe,branch pipe and diffusion chamber pipe.In addition,an easy method is provided to calculate the attenuation rate of the shock wave in single and multi-stage ventilation pipes.Corresponding parameters are provided for various structures,and the margin of error between the formulae and experimental results is within 10%,which is significant for engineering applications.展开更多
BACKGROUND Gastroesophageal reflux disease(GERD)is common among neonates,particularly those requiring mechanical ventilation.Pepsin,a reliable marker of gastric aspi-ration,may help detect GER episodes in ventilated n...BACKGROUND Gastroesophageal reflux disease(GERD)is common among neonates,particularly those requiring mechanical ventilation.Pepsin,a reliable marker of gastric aspi-ration,may help detect GER episodes in ventilated neonates and assess associated clinical outcomes.AIM To determine the incidence of GERD,associated risk factors,and morbidities among full-term mechanically ventilated neonates by detecting pepsin in endo-tracheal aspirates(ETA).METHODS This study included 97 full-term neonates admitted to the neonatal intensive care unit at Cairo University Hospitals from April 2023 to March 2024.ETA samples were collected at three intervals:Immediately post-intubation(Sample A),48 hours after intubation(Sample B),and just before extubation(Sample C).Pepsin concentration was measured using enzyme-linked immunosorbent assay.Clinical data,including hospital stay duration and feeding parameters,were correlated with pepsin levels.RESULTS Pepsin was detected in 76(78.4%)of Sample A,78(81.3%)of Sample B,and 47(68.1%)of Sample C.A significant positive correlation was found between pepsin levels and FiO_(2) in Sample B(r=0.203,P=0.047).Prolonged hospital stay was also associated with pepsin detection in Samples B and C(P<0.05).A negative correlation was observed between feeding amount and pepsin levels across all samples(P<0.05).CONCLUSION The incidence of GERD in full-term mechanically ventilated neonates is high,correlating with pepsin levels,FiO_(2),feeding intolerance,and hospital stay,highlighting the importance of early detection.展开更多
The reported study examines the diurnal and seasonal variations of tropospheric ozone and its precursors in Bangalore,India,from January to December 2020,and explores the impact of meteorological parameters and the ve...The reported study examines the diurnal and seasonal variations of tropospheric ozone and its precursors in Bangalore,India,from January to December 2020,and explores the impact of meteorological parameters and the ventilation coefficient(VC)on ozone levels.Tropospheric ozone,a significant secondary pollutant,poses a major environmental and health challenge in urban areas.The study focuses on ozone,nitrogen oxides(NO and NO2),Sulphur dioxide(SO2),and carbon monoxide(CO),revealing that ozone peaks in the early afternoon due to solar radiation,while precursor pollutants show morning and evening peaks linked to traffic emissions.Higher ozone levels occur in winter(due to reduced boundary layer height)and summer(due to increased photochemical activity),while the monsoon period shows the lowest levels due to the washout effect.The VC values are generally higher during the day(587 m^(2)/s)compared to night(246 m^(2)/s),with the highest recorded in summer(1,935 m^(2)/s)and the lowest in the post-monsoon season(209 m^(2)/s).Higher VC enhances pollutant dispersion,while lower VC leads to accumulation.However,surface ozone concentrations increase with higher VC due to photochemical processes.The findings highlight the complex interplay of meteorology,emissions,and boundary layer dynamics,informing strategies for urban air quality management.展开更多
The longitudinal ventilation strategy is commonly used for road tunnels in urban environment in Sweden.This is partly due to how tunnels in urban environment was planned and designed before the EU Directive[1](2004/54...The longitudinal ventilation strategy is commonly used for road tunnels in urban environment in Sweden.This is partly due to how tunnels in urban environment was planned and designed before the EU Directive[1](2004/54/EC)came in place.Even in new tunnels both to practical and economic reasons the use of longitudinal ventilation has been an outspoken demand from the Swedish road authority,SRA.Swedish law[2]requires that a risk analysis is carried out to demonstrate that an acceptable level of risk is achieved in the tunnels with longitudinal ventilation if there is a risk of queues.Otherwise transverse or semi-transverse ventilation strategy shall be used.During recent development,or a late awakening,it is clear that dense populated areas in Sweden will experience queues.This threatens the foundation of the Swedish modern tunnel safety concept which calls for enhancement.This paper presents the risk-reducing effect of three alternative strategies,enhancements package,focusing on evacuation safety for road users.It is a combination of traffic management,fixed firefighting systems,reduced distance between escape routes and regulation of traffic with dangerous goods.In addition,it provides a comprehensive review of safety system details,combined with a longitudinal ventilation concept.展开更多
BACKGROUND Lung ultrasonography is being increasingly used in mechanically ventilated patients to evaluate the lung aeration during incremental positive end expiratory pressure(PEEP)adjustments and to evaluate the wea...BACKGROUND Lung ultrasonography is being increasingly used in mechanically ventilated patients to evaluate the lung aeration during incremental positive end expiratory pressure(PEEP)adjustments and to evaluate the weaning process from mechanical ventilation.The effects of PEEP may vary across different lung pathologies and may not consistently correlate with changes in lung aeration as assessed by lung ultrasound scores(LUSs).AIM To assess the role of lung ultrasonography in evaluating lung aeration during the application of PEEP in mechanically ventilated patients with various lung pathologies.METHODS An observational study was conducted over 18 months in a tertiary care hospital.Patients of both genders,aged between 18-75 years,who had been admitted to the intensive care unit,and required mechanical ventilation,were studied.A standard ventilatory strategy was used and incremental levels of PEEP[5,10,and 15 cm water(H_(2)O)]were applied.Baseline characteristics,including oxygen saturation(SpO2),LUS,mean arterial pressure(MAP),heart rate(HR),and their changes with incremental PEEP levels,were recorded and analyzed.RESULTS In this study,45.9%of patients required a PEEP of 5 cm H_(2)O to achieve the endpoint of lung aeration(LUS of 0).In addition,86.5% and 13.5% of patients reached the endpoint of lung aeration at PEEP levels of 10 and 15 cm H_(2)O,respectively.The proportion of patients with higher lung scores decreased significantly with increasing PEEP levels(P<0.001 for 5 and 10 cm H_(2)O and P=0.032 for 15 cm H_(2)O).SpO2 increased significantly with higher PEEP levels(P<0.001),confirming the effectiveness of PEEP in improving oxygenation.The results also revealed a significant increase in HR and a decrease in MAP following the application of higher PEEP levels.CONCLUSION Increasing PEEP levels in mechanically ventilated patients improves lung aeration,which can be effectively assessed using bedside lung ultrasonography.展开更多
文摘Heat Recovery Ventilators(HRVs)are essential for improving indoor air quality(IAQ)and reducing energy consumption in residential buildings situated in cold climates.This study considers the efficiency and performance optimization of HRVs under cold climatic conditions,where conventional ventilation systems increase heat loss.A comprehensive numerical model was developed using COMSOL Multiphysics,integrating fluid dynamics,heat transfer,and solid mechanics to evaluate the thermal efficiency and structural integrity of an HRV system.The methodology employed a detailed geometry with tetrahedral elements,temperature-dependent material properties,and coupled governing equations solved under Tehran-specific boundary conditions.A multi-objective optimization was implemented in the framework of the Nelder-Mead simplex algorithm,targeting the maximization of the average outlet temperature and minimization of the maximum von Mises thermal stress,with inlet flow velocity as the design variable(range:0.5–1.2m/s).Results indicate an optimal velocity of 0.51563 m/s,achieving an average outlet temperature of 289.44 K and maximum von Mises stress of 221 MPa,validated through mesh independence and detailed contour analyses of temperature,velocity,and stress distributions.
基金The research presented in this paper was performed as a part of the Project AMSEP“Novel dry sorter for coal processing and coal recovery from mine originating wastes”,which was conducted with a financial grant from the European Institute of Innovation and Technology in frame of InnoEnergy S.E.,with Central Mining Institute as the Project coordinator.It was also financially supported by Statutory Research No.11325018-173.
文摘Hard coal is an important source of energy worldwide.Owing to the imperfections of excavation technology,most run-of-mine coals must be processed before they can be utilised as fuel.In this study,tests on the dry separation process were performed with numerous different raw hard coal and coal waste material samples,using a newly designed and constructed negative-pressure pneumatic separator(NPPS).The experiments revealed the effects of the feed-material properties and material processing conditions.These experiments were preceded by additional tests for evaluating the influence of each device operating parameter on the process,to determine the optimal method of supplying the feed material.The calorific value of the processed materials was improved by 5%–40%,while a minimal output yield of products(60%–70%)was maintained.The trials indicated that in coal material processing,the developed NPPS can be used for not only raw coal enrichment but also coal recovery from materials stored at coal-waste dumps.The main advantages of the device are its mobility,low material processing cost,and lack of water consumption during operation.
基金National Natural Science Foundation of China(Grant No50578034)Shanghai Educational Development Foundationtitled"Shuguang Project"(Grant NO03SG30)
文摘Considering four different climate zones in China, an investigation on the choice of heat recovery ventilator for the buildings with little moisture emissions is carried out. The annual composition of energy consumption of air intake for per unitary air ventilation flow rate is evaluated by employing the testing data of climatic parameters in eight selected cities. The analysis shows that the total heat recovery is suitable in a controlled ventilation system with air humidity controlled during heating period of all the climates. For the building without air humidity controlled in winter, the sensible heat recovery ventilators can be used in severe cold and cold regions, and total heat recovery systems are more suitable for energy saving in hot summer and cold winter and hot summer and warm winter regions.
文摘A study was carried out to control the noise produced by the ventilators at the Luling coalmine, which had caused serious noise pollution to the residents living around the mine for a long time. The main noise source was found to be the dynamic noise at the outlet of the diffuser. The frequency of its peak value was 250 Hz. A special brick with a resonant frequency of 250 Hz was designed to eliminate this noise. The diffusion of a lower frequency noise has been successfully controlled by the installation of a noise-eliminating tower above the diffuser outlet. The detection results show that the noise in the nearby residential area has been lowered to an average 55.3dB(A) in the daytime from 69.8dB(A) and to 48.4dB(A) at night from 65.8dB(A).
基金funded by Central Guidance for Local Science and Technology Development Funding Projects under Grant,China(Grant No.ZYYD2025ZY11)the National Natural Science Foundation of China(Grant Nos.32460449 and 52265041)+1 种基金the Key Laboratory of Modern Agricultural Equipment and Technology(Jiangsu University),Ministry of Education,China(Grant No.MAET202305)the Graduate School-level Research and Innovation Program of Xinjiang Agricultural University,China(Grant No.XJAUGRI2023021).
文摘Safflower is one of the most important oil crops worldwide.To improve the efficiency and quality of harvesting soft safflower filaments,minimize filament damage by the blade,and ensure the integrity of the filaments,an end-effector with a rotary push-cut-type negative-pressure airflow was designed.The design of the rotary blade edge curve was based on Archimedean and logarithmic spirals.The effect of the Archimedean spiral on the pushing of the scattered filaments was investigated.The rotary-cutting force and speed of the logarithmic helix on the soft filaments were analyzed.The sliding cut angle and feed speed of the blade are the key factors governing filament removal and damage.A simulation model of the cutting chamber flow field was established for the change in airflow with the position and speed rotation of the blade,allowing analysis of the parameters of the negative-pressure airflow.Single-factor and Box-Behnken tests were performed with the sliding cut angle,blade feed speed,and negative-pressure airflow speed as influencing factors and filament removal,damage,and drop rate as indices.The response surface clarified the effects of various factors on these indices.Optimal parameters were a sliding cut angle of 32.20°,a blade feeding speed of 0.031 m/s,and a negative-pressure airflow speed of 4.57 m/s.The corresponding filament removal,damage,and drop rates were 93.47%,6.94%,and 4.33%,respectively.Optimization results showed that filament removal,damage,and drop rates were 93.50%,7.02%,and 4.43%,respectively.The harvesting process met the requirements of high efficiency and low damage.
文摘Objective:To investigate the application effect of intelligent empowerment standardized airway management process in patients receiving mechanical ventilation.Methods:A retrospective analysis was conducted on the clinical data of 79 EICU inpatients who underwent tracheal intubation and mechanical ventilation treatment at our hospital from January 2023 to May 2025.The patients were divided into a control group(conventional airway management process,n=40)and a study group(intelligent empowerment standardized airway management process,n=39)based on the intervention protocols they received.Oral health scores,dental plaque index,oral odor,serum inflammatory markers[C-reactive protein(CRP),procalcitonin(PCT)],clinical pulmonary infection score(CPIS),as well as the incidence of ventilator-associated pneumonia(VAP),duration of mechanical ventilation,and length of stay in the EICU were assessed before and after treatment.Results:The baseline values of all indicators were consistent between the two groups before intervention(p>0.05).After corresponding interventions,both groups showed significant improvements in Beck oral health scores,dental plaque index,and oral odor,with more pronounced improvements observed in the study group(p<0.05).After the intervention,the research group showed a significant decrease in serum CRP and PCT levels,as well as CPIS scores(p<0.05).In contrast,the control group experienced an increase in these three indicators to a certain extent(p<0.05).Moreover,the incidence of ventilator-associated pneumonia(VAP),duration of mechanical ventilation,and length of stay in the EICU were all lower in the research group compared to the control group,while the nurse’s compliance rate with the protocol was higher in the research group(p<0.05).Conclusion:The standardized airway management protocol empowered by intelligent technology can significantly improve nursing compliance,benefit oral health status,reduce the risk of pulmonary infection and systemic inflammation levels,and promote rapid patient recovery,demonstrating considerable potential for widespread adoption.
基金Outstanding Young Investigator Program of Capital Medical University,Grant/Award Number:A2308。
文摘Phrenic nerve stimulation(PNS)may preserve diaphragm activation and mitigate multiorgan injury during mechanical ventilation(MV);however,a minimal invasive rat model integrating PNS with MV is lacking.We established an omohyoid muscle-based PNS rat model combined with MV.Bilateral nerves were exposed within 20±2 min by transection at the intermediate tendon of omohyoid muscle,minimizing trauma and bleeding.Threshold stimulation(0.6±0.2 mA)correlated with body weight.Ventilator-synchronized stimulation increased compound muscle action potentials by~30%,whereas histology confirmed intact nerve.Physiological parameters remained stable throughout ventilation.This model provides a safe and scalable platform for mechanistic and preclinical studies on PNS-mediated protection against MV-induced organ injury.
文摘Severe acute pancreatitis(SAP)can induce acute respiratory distress syndrome(ARDS)and abdominal compartment syndrome(ACS).Although prone position ventilation(PPV)can improve outcomes in patients with ARDS,there is significant controversy regarding its concurrent use with ACS owing to concerns of increased risk of intra-abdominal pressure(IAP).[1]We present a case of successful PPV application without adverse eff ects.
基金supported by the National Natural Science Foundation of China(81930049 and 82171926).
文摘A recent study on the rapid imaging of pulmonary ventilation using hyperpolarized ^(129)Xe MRI has demonstrated the ability to achieve isotropic 3D ventilation imaging with a spatial resolution of 3×3×3mm^(3) in humans,within an acquisition time of just 3.5 seconds(https://doi.org/10.1002/mrm.30120).
文摘Prediction of weaning success from invasive mechanical ventilation remains a challenge in everyday clinical practice.Several prediction scores have been developed to guide success during spontaneous breathing trials to help with weaning decisions.These scores aim to provide a structured framework to support clinical judgment.However,their effectiveness varies across patient populations,and their predictive accuracy remains inconsistent.In this review,we aim to identify the strengths and limitations of commonly used clinical prediction tools in assessing readiness for ventilator liberation.While scores such as the Rapid Shallow Breathing Index and the Integrative Weaning Index are widely adopted,their sensitivity and specificity often fall short in complex clinical settings.Factors such as underlying disease pathophysiology,patient characteristics,and clinician subjectivity impact score performance and reliability.Moreover,disparities in validation across diverse populations limit generalizability.With growing interest in artificial intelligence(AI)and machine learning,there is potential for enhanced prediction models that integrate multidimensional data and adapt to individual patient profiles.However,current AI approaches face challenges related to interpretability,bias,and ethical implementation.This paper underscores the need for more robust,individualized,and transparent prediction systems and advocates for careful integration of emerging technologies into clinical workflows to optimize weaning success and patient outcomes.
基金support by Technology R&D Program of China State Railway Group Co.,Ltd(Grant number N2022J013)the Hunan Provincial Innovation Foundation for Postgraduate(Grant number CX20220279)+1 种基金the Fundamental Research Funds for the Central Universities of Central South University(Grant number 2022ZZTS0193)China Scholarship Council(202106370112)。
文摘During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air ducts.In this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment simulation.In addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle tests.The results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other train.During train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching 3.2.The average mass flow falls below the rated mass flow for the converter.Compared to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,respectively.Compared to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,respectively.These findings provide valuable insights into the design and operation of high-speed trains.
文摘BACKGROUND:In this study,we aimed to evaluate the impact of mechanical ventilator(MV)utilizaton during cardiopulmonary resuscitation(CPR)on out-of-hospital cardiac arrest(OHCA)patient clinical outcomes in the emergency department.METHODS:This single-centered,retrospective,case-control study analyzed electronic medical records.Patients aged>18 years with non-traumatic OHCA who were treated at an emergency medical center between January 2019 and December 2023 were included.These patients were accessed according to the ventilatory method used:MV ventilation(volume control,tidal volume 6-8 mL/kg,frequency 10 beat per minute,inspiratory time 1 s)and manual resuscitator bag valve(BV)ventilation.The primary outcome was the return of spontaneous circulation(ROSC).After 1:1 propensity score matching,the clinical outcomes were analyzed.RESULTS:A total of 649 patients were enrolled in this study.Before matching,the clinical outcomes and pneumothorax incidence did not differ between the MV and BV groups.After 1:1 matching between the two groups using propensity scores,522 patients(261 MV and 261 BV)were analyzed.Propensity score matching yielded an adequate balance(standardized mean difference<0.10)for all covariates.The estimated odds ratio(OR)for ROSC was 1.23(95%confidence interval[CI]:0.85-1.77;P=0.267),for survival at hospital admission was 1.02(95%CI:0.68-1.53;P=0.918),for survival at hospital discharge was 2.31(95%CI:1.10-5.20;P=0.033),and for good neurologic outcome was 2.56(95%CI:0.84-9.43;P=0.116).CONCLUSION:In patients with OHCA admitted to the emergency department,MV ventilation during CPR showed clinical outcomes similar to those of BV ventilation in most measures.However,survival at hospital discharge was significantly higher in the MV group,suggesting potential benefits of MV use in selected patients.
文摘BACKGROUND There has been a growing interest in noninvasive ventilation(NIV)in comparison to invasive mechanical ventilation(IMV)as a standard of care for acute respiratory failure(ARF),especially in the post-covid era,but direct head-to-head cost comparisons between the two modalities are not available in literature.AIM To compare the cost along with the clinical effectiveness of NIV in comparison to IMV in ARF.METHODS A prospective observational single-center case control study including adult patients with ARF(PaO2/FiO2 ratio<300)admitted from January 1,2024 to December 31,2024 in medical intensive care unit(ICU)of a tertiary care hospital requiring either NIV or invasive ventilation.NIV and IMV groups were compared based on average length of ICU and hospital stay,mortality,net cost of ICU treatment,need for intubation and tracheostomy.RESULTS A total of 319 patients were included in the study(197 in NIV,122 in IMV group).Statistically significant difference in length of ICU stay(NIV group:5±3.25 days,IMV group:9±2.6 days;P<0.05)and mortality rate was seen(11%NIV vs 34%IMV;P<0.01).On multivariate analyses,mortality showed a stronger association with IMV[odds ratio(OR)=7.73;95%CI:3.12-19.18]as compared to ICU stay(OR=2.73;95%CI:2.15-3.48).A total of 33 patients(17%)in NIV group required intubation of which 3 were tracheostomized,while 14 patients(11%)in IMV group needed tracheostomy.The net average cost of ICU stay was₹83902 in NIV group while in IMV group,the net ICU cost was₹476216.The average cost of ICU stay was five times higher with IMV.CONCLUSION NIV has potential economic and clinical benefits as compared to invasive ventilation in ARF.
文摘Mechanical ventilation is a specialized oxygen therapy and life support technology with significant importance for critically ill patients. In fact, 40%–66% of patients in the intensive care unit(ICU) require mechanical ventilation.^([1,2]) However, the mechanical ventilation can lead to ventilatorassociated lung injury(VALI),^([3]) ultimately resulting in difficulties in weaning from mechanical ventilation,prolonged hospital stays, and even increased mortality.
基金supported by the National Natural Science Foundation of China(No.12372049)the Independent Project of State Key Laboratory of Rail Transit Vehicle System(No.2025RVL-QY-T24),China.
文摘Variable air volume systems are widely used in trains as they provide effective energy savings for air conditioning.However,the design phase is usually carried out at a certain fixed airflow,resulting in a difference between the expected and actual flow fields.In this study,we first analyzed the flow field characteristics at variable airflow rates under isothermal conditions,and subsequently established a correlation equation between the airflow and the flow field parameters.The results show that the airflow just entering the compartment conforms to the characteristics of an attached jet,and then,after converging in the middle,conforms to the characteristics of a free jet.The flow field characteristics are significantly correlated with the Reynolds number(Re)and are limited by the small space inside the vehicle.When Re≥2650,the axial velocities all conform to the classical u_(m)/u_(0)−(x/b)^(r) or u_(m)/u_(0)−(y/b)^(r) law,the sectional velocities conform to the exponential and Gaussian distributions,and the characteristic thicknesses of the jets conform to a linear distribution.Derivation shows that the entrainment suction flow rate is related mainly to the initial flow rate and the air opening width.The results of this study will inform the design of ventilation systems for high-speed trains.
文摘With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ventilation pipes of different structures are investigated by experiments and numerical simulations.Furthermore,for the same structure,the effects of peak pressure and positive pressure time on the attenuation rate are discussed.It is found that the attenuation rate increases with the incident shock wave pressure,and the shock wave attenuation rate tends to reach its limiting value k for the same structure and reasonably short positive pressure time.Under the same conditions,the attenuation rate is calculated using the pressure of the shock wave as follows:diffusion chamber pipe,branch pipe and selfconsumption pipe;the attenuation rate per unit volume is calculated as follows:self-consumption pipe,branch pipe and diffusion chamber pipe.In addition,an easy method is provided to calculate the attenuation rate of the shock wave in single and multi-stage ventilation pipes.Corresponding parameters are provided for various structures,and the margin of error between the formulae and experimental results is within 10%,which is significant for engineering applications.
文摘BACKGROUND Gastroesophageal reflux disease(GERD)is common among neonates,particularly those requiring mechanical ventilation.Pepsin,a reliable marker of gastric aspi-ration,may help detect GER episodes in ventilated neonates and assess associated clinical outcomes.AIM To determine the incidence of GERD,associated risk factors,and morbidities among full-term mechanically ventilated neonates by detecting pepsin in endo-tracheal aspirates(ETA).METHODS This study included 97 full-term neonates admitted to the neonatal intensive care unit at Cairo University Hospitals from April 2023 to March 2024.ETA samples were collected at three intervals:Immediately post-intubation(Sample A),48 hours after intubation(Sample B),and just before extubation(Sample C).Pepsin concentration was measured using enzyme-linked immunosorbent assay.Clinical data,including hospital stay duration and feeding parameters,were correlated with pepsin levels.RESULTS Pepsin was detected in 76(78.4%)of Sample A,78(81.3%)of Sample B,and 47(68.1%)of Sample C.A significant positive correlation was found between pepsin levels and FiO_(2) in Sample B(r=0.203,P=0.047).Prolonged hospital stay was also associated with pepsin detection in Samples B and C(P<0.05).A negative correlation was observed between feeding amount and pepsin levels across all samples(P<0.05).CONCLUSION The incidence of GERD in full-term mechanically ventilated neonates is high,correlating with pepsin levels,FiO_(2),feeding intolerance,and hospital stay,highlighting the importance of early detection.
文摘The reported study examines the diurnal and seasonal variations of tropospheric ozone and its precursors in Bangalore,India,from January to December 2020,and explores the impact of meteorological parameters and the ventilation coefficient(VC)on ozone levels.Tropospheric ozone,a significant secondary pollutant,poses a major environmental and health challenge in urban areas.The study focuses on ozone,nitrogen oxides(NO and NO2),Sulphur dioxide(SO2),and carbon monoxide(CO),revealing that ozone peaks in the early afternoon due to solar radiation,while precursor pollutants show morning and evening peaks linked to traffic emissions.Higher ozone levels occur in winter(due to reduced boundary layer height)and summer(due to increased photochemical activity),while the monsoon period shows the lowest levels due to the washout effect.The VC values are generally higher during the day(587 m^(2)/s)compared to night(246 m^(2)/s),with the highest recorded in summer(1,935 m^(2)/s)and the lowest in the post-monsoon season(209 m^(2)/s).Higher VC enhances pollutant dispersion,while lower VC leads to accumulation.However,surface ozone concentrations increase with higher VC due to photochemical processes.The findings highlight the complex interplay of meteorology,emissions,and boundary layer dynamics,informing strategies for urban air quality management.
文摘The longitudinal ventilation strategy is commonly used for road tunnels in urban environment in Sweden.This is partly due to how tunnels in urban environment was planned and designed before the EU Directive[1](2004/54/EC)came in place.Even in new tunnels both to practical and economic reasons the use of longitudinal ventilation has been an outspoken demand from the Swedish road authority,SRA.Swedish law[2]requires that a risk analysis is carried out to demonstrate that an acceptable level of risk is achieved in the tunnels with longitudinal ventilation if there is a risk of queues.Otherwise transverse or semi-transverse ventilation strategy shall be used.During recent development,or a late awakening,it is clear that dense populated areas in Sweden will experience queues.This threatens the foundation of the Swedish modern tunnel safety concept which calls for enhancement.This paper presents the risk-reducing effect of three alternative strategies,enhancements package,focusing on evacuation safety for road users.It is a combination of traffic management,fixed firefighting systems,reduced distance between escape routes and regulation of traffic with dangerous goods.In addition,it provides a comprehensive review of safety system details,combined with a longitudinal ventilation concept.
文摘BACKGROUND Lung ultrasonography is being increasingly used in mechanically ventilated patients to evaluate the lung aeration during incremental positive end expiratory pressure(PEEP)adjustments and to evaluate the weaning process from mechanical ventilation.The effects of PEEP may vary across different lung pathologies and may not consistently correlate with changes in lung aeration as assessed by lung ultrasound scores(LUSs).AIM To assess the role of lung ultrasonography in evaluating lung aeration during the application of PEEP in mechanically ventilated patients with various lung pathologies.METHODS An observational study was conducted over 18 months in a tertiary care hospital.Patients of both genders,aged between 18-75 years,who had been admitted to the intensive care unit,and required mechanical ventilation,were studied.A standard ventilatory strategy was used and incremental levels of PEEP[5,10,and 15 cm water(H_(2)O)]were applied.Baseline characteristics,including oxygen saturation(SpO2),LUS,mean arterial pressure(MAP),heart rate(HR),and their changes with incremental PEEP levels,were recorded and analyzed.RESULTS In this study,45.9%of patients required a PEEP of 5 cm H_(2)O to achieve the endpoint of lung aeration(LUS of 0).In addition,86.5% and 13.5% of patients reached the endpoint of lung aeration at PEEP levels of 10 and 15 cm H_(2)O,respectively.The proportion of patients with higher lung scores decreased significantly with increasing PEEP levels(P<0.001 for 5 and 10 cm H_(2)O and P=0.032 for 15 cm H_(2)O).SpO2 increased significantly with higher PEEP levels(P<0.001),confirming the effectiveness of PEEP in improving oxygenation.The results also revealed a significant increase in HR and a decrease in MAP following the application of higher PEEP levels.CONCLUSION Increasing PEEP levels in mechanically ventilated patients improves lung aeration,which can be effectively assessed using bedside lung ultrasonography.
