Ventilation Conditions Research Articles

Evaluation of radiation dose associated with underground uranium mining activities in east Singhbhum, Jharkhand, India

Evaluation of radiation dose associated with underground uranium mining activities in east Singhbhum, Jharkhand, India

Numerical investigation of different building configurations for improving outdoor spatial ventilation conditions in strip-type residential neighbourhoods

Numerical investigation of different building configurations for improving outdoor spatial ventilation conditions in strip-type residential neighbourhoods

Does the Addition of Oral Sampling Improve Waveform Capnography When Compared to Traditional Nasal Sampling in Open-Airway Patients?

End-tidal carbon dioxide (EtCO2) is an invaluable anesthesia measure due to minimal delay in monitoring ventilation. Oral and Maxillofacial Surgery (OMS) presents special challenges because oral exhalations are not sampled effectively via nasal cannula normally used to avoid interfering with procedures. The purpose of the study was to compare EtCO2 waveforms obtained in subjects using nasal monitoring and combined nasal and oral monitoring under simulated ventilatory conditions. A single-blinded, randomized crossover controlled study was conducted at the University of Illinois Chicago with healthy volunteers, who were blinded to the monitoring system used. Inclusion criteria required subjects be≥18years of age, be consentable, and English-speaking. Exclusion criteria required no airway abnormalities, no edentulism, and no conditions that preclude undergoing an OMS procedure under sedation. The primary predictor variable was the EtCO2 monitoring system: nasal with a standard nasal cannula, and combined with a nasal cannula and oral device. The secondary predictor variable evaluated 3 ventilatory states (nasal breathing, oral breathing, and apnea) in each arm, standardizing by maintaining consistent breath counts across observation periods. The main outcome variable was the number of waveforms recorded over 30seconds for nasal and combined monitoring. Each recording was standardized by dividing it by the baseline waveforms and multiplying by 20. Higher values, closer to baseline, were considered more accurate depictions of ventilation. Covariates were body mass index (BMI), age, sex, Mallampati score, and breathing method. Analysis of variance, analysis of covariance, and multivariate analysis of variance were performed. P value < .05 was considered statistically significant. The sample included 25 subjects (18 male and 7 female) with mean age 29.9±7.98years and BMI 23.9±3.51kg/m2. Combined sampling detected more waveforms during nasal and oral breathing (P<.001). Higher BMI correlated with reduced waveform capture during nasal sampling in oral breathing (P=.013). Combined sampling detected more waveforms during nasal breathing (P=.005) in subjects with BMI < 23.5kg/m2. Mallampati score correlated with increased waveforms during nasal breathing. Oral EtCO2 sampling may improve accuracy of capnography waveform capture. Further clinical studies in sedated subjects undergoing OMS procedures are needed.

A new ventilation performance index considering relative changes in environmental parameters: A numerical study

A new ventilation performance index considering relative changes in environmental parameters: A numerical study

Feasibility assessment of a clean and efficient fire extinguishing system for pottery jar liquor warehouses

Clean fire extinguishing systems applicable to the pottery jar liquor warehouse are in demand. In this study, taking 53vol% liquor as the research subject, fire models of various clean fire extinguishing systems comprising water mist, liquid carbon dioxide (LCO2) and liquid nitrogen (LN2) were established using a fire dynamic simulator to determine their fire extinguishing effect. A feasibility assessment of systems was performed under different fire source types, fire source sizes, and ventilation conditions. The fire extinguishing efficiency was analyzed in terms of the fire extinguishing time, oxygen concentration, and space temperature. The results showed that the success rate of the LCO2 and LN2 fire extinguishing systems was 100%, whereas the success rate of the water mist fire extinguishing system was 95%. In terms of reducing the oxygen concentration at the bottom of the space and the temperature in the space, the LCO2 system exhibited the best performance, followed by the LN2 system, and lastly the water mist. Under different ventilation conditions and fire source types, the LCO2 fire extinguishing system was least affected, whereas the effectiveness of the water mist fire extinguishing system reduced under natural ventilation conditions, and the extinguishing efficiency of the LN2 fire extinguishing system was affected by the fire source type. Overall, the LCO2 system presented more advantages in extinguishing fires in pottery jar liquor warehouses and can provide a new idea for the development and application of clean and efficient fire extinguishing systems.

Factor analysis and GA-BP-ANN prediction of nitrogen diffusion behavior in underground laboratory under ventilation conditions

Nitrogen is widely used in various laboratories as a suppressive gas and a protective gas. Once nitrogen leaks and accumulates in a such confined space, it will bring serious threats to the experimental staff. Especially in underground tunnels or underground laboratories where there is no natural wind, the threat is more intense. In this work, the ventilation design factors and potential leakage factors are identified by taking the leakage and diffusion of a large liquid nitrogen tank in China Jinping Underground Laboratory (CJPL) as an example. Based on computational fluid dynamics (CFD) research, the effects of fresh air inlet position, fresh air velocity, exhaust outlet position, leakage hole position, leakage hole size, and leaked nitrogen mass flow rate on nitrogen diffusion behavior in specific environments are discussed in detail from the perspectives of nitrogen concentration field and nitrogen diffusion characteristics. The influencing factors are parameterized, and the Latin hypercube sampling (LHS) is used to uniformly sample within the specified range of each factor to obtain samples that can represent the whole sample space. The nitrogen concentration is measured by numerical value, and the nitrogen diffusion characteristics are measured by category. The GA-BP-ANN numerical regression and classification regression models for nitrogen concentration prediction and nitrogen diffusion characteristics prediction are established. By using various rating indicators to evaluate the performance of the trained model, it is found that models have high accuracy and recognition rate, indicating that it is effective in predicting and determining the concentration value and diffusion characteristics of nitrogen according to ventilation factors and potential leakage factors. The research results can provide a theoretical reference for the parametric design of the ventilation system.

Acceleration analysis and unsteady mathematical prediction of flame spread over thermal insulation layer in u-shaped building façade fires

Acceleration analysis and unsteady mathematical prediction of flame spread over thermal insulation layer in u-shaped building façade fires

Performance-based fire assessment of a fully automated multi-storey steel parking structure: A computational approach

Performance-based fire assessment of a fully automated multi-storey steel parking structure: A computational approach

Impact of air supply cessation time on thermal characteristics in coal mine dead-end roadway fires: An experimental study

Impact of air supply cessation time on thermal characteristics in coal mine dead-end roadway fires: An experimental study

The Impact of Different Ventilation Conditions on Electric Bus Fires

Once a fire breaks out in an electric bus, it can easily lead to mass casualties and severe injuries, resulting in significant property damage and social impact. The high-temperature smoke and toxic gases in an electric bus fire are key factors that cause a large number of casualties, both of which are closely related to ventilation conditions. In view of this, this study utilized the Fire Dynamics Simulator (FDS 6) software to establish a three-dimensional experimental model of an electric bus. Numerical simulations of the fire combustion process in the electric bus under different ventilation conditions were conducted. Multiple fire scenes were established based on varying ventilation areas, different wind speeds, and diverse window opening positions. This study specifically analyzed the temperature and CO concentration variations under different fire scenes. By comparing the simulation results under different ventilation conditions, it can be concluded that when an electric bus catches fire, opening 100% of the windows, the wind speed is 8 m/s, and opening the rear window of the electric bus first can minimize the fire risk. Through the numerical simulation of electric bus fires under various conditions, this study analyzed the impact of different ventilation conditions on electric bus fires, providing a theoretical basis for firefighting and rescue efforts as well as personnel evacuation in electric bus fire incidents, with the ultimate goal of maximizing public safety.

Airborne Influenza Virus in Daycare Centers.

In this study, we investigated the concentration of airborne influenza virus in daycare centers and influencing factors, such as common cold prevalence, air pollutants, and meteorological factors. A total of 209 air samples were collected from daycare centers in Kaohsiung and the influenza virus was analyzed using real-time quantitative polymerase chain reaction. Air pollutants and metrological factors were measured using real-time monitoring equipment. Winter had the highest positive rates of airborne influenza virus and the highest prevalence of the common cold, followed by summer and autumn. The concentration of CO was significantly positively correlated with airborne influenza virus. Daycare center A, with natural ventilation and air condition systems, had a higher concentration of airborne influenza A virus, airborne fungi, and airborne bacteria, as well as a higher prevalence of the common cold, than daycare center B, with a mechanical ventilation system and air purifiers, while the concentrations of CO2, CO, and UFPs in daycare center A were lower than those in daycare center B. We successfully detected airborne influenza virus in daycare centers, demonstrating that aerosol sampling for influenza can provide novel epidemiological insights and inform the management of influenza in daycare centers.

Ventilation improvement for effective protection of healthcare workers in negative pressure airborne infectious isolation room from viral aerosols

Ventilation improvement for effective protection of healthcare workers in negative pressure airborne infectious isolation room from viral aerosols

Study on the influence of branch slope on smoke movement mechanism in bifurcated tunnel fire under natural ventilation

Study on the influence of branch slope on smoke movement mechanism in bifurcated tunnel fire under natural ventilation

Optimizing air inlet designs for enhanced natural ventilation in indoor substations: A numerical modelling and CFD simulation study

Optimizing air inlet designs for enhanced natural ventilation in indoor substations: A numerical modelling and CFD simulation study

Hubungan Karakteristik Individu dan Sanitasi Lingkungan Terhadap Keberhasilan Pengobatan Tuberculosis di RSUD Bengkalis

Mycobacterium tuberculosis is a pathogenic bacterium that is the causative agent of tuberculosis. The treatment of tuberculosis is a lengthy process that may induce boredom and lead to the cessation of medication in patients, which can result in the development of bacterial resistance to multiple anti-tuberculosis drugs. Many factors affected the success of tuberculosis treatment include individual characteristics such as age, education, occupation, and environmental conditions such as occupancy density, ventilation, lighting and floor condition. The objective of the study was to know correlation between individual characteristic and home environment with the success of tuberculosis treatment. The observational retrospective and analytics design were applied, which the research population were 30 individual tuberculosis patients who have been regularly without stop taking antibiotics for 6 months or more at the Bengkalis District Hospital. The results demonstrated that all participant have taken tuberculosis antibiotics drugs for more than 6 months and GeneXpert results confirmed 2 patients (6,7%) exhibited positive results for Mycobacterium tuberculosis, and 28 patients (93,3%) exhibited negative results. The individual characteristic such as education level, occupation and enveromental sanitation related to unsuccessful tuberculosis treatment. The findings of this study indicate a need for further examination of the presence of Mycobacterium tuberculosis in patients who have completed treatment, with the objective of ensuring the absence of Mycobacterium tuberculosis in the patient's body.

Investigating the Impact of Green Space Ratio and Layout on Bioaerosol Concentrations in Urban High-Density Areas: A Simulation Study in Beijing, China

The COVID-19 pandemic significantly impacted global development. Through bioaerosols emitted by human respiration, respiratory infectious diseases, including COVID-19, are transmitted. The bioaerosol concentrations can be affected by the urban climate and morphology. However, the effects of urban green spaces on bioaerosol concentrations remain unclear. Focusing on the dormitory area of Beijing Forestry University, this study first investigated the influence of different green space ratios on the average bioaerosol concentrations using the ENVI-met software. Moreover, both overall and local green space layouts were analyzed for their impact on bioaerosol concentrations. The results indicated that ventilation conditions were the primary factor influencing bioaerosol concentrations. During peak congestion, a 10% increase in the green space ratio resulted in a 2% rise in the average bioaerosol concentration. Furthermore, a distributed layout resulted in a 1.3% higher average bioaerosol concentration than a concentrated layout with an equivalent green space ratio. Enacting strategies such as Roadside Green Spaces Retreat, Road Spaces Expansion, and Intersection Green Spaces Chamfering led to reductions in local bioaerosol concentrations by up to 17.7%, 18.44%, and 12.69%, respectively. This study highlights the importance of adjusting green space layouts in urban high-density areas after the pandemic, reducing the risk of population exposure to bioaerosol concentrations.

The application of electrical impedance tomography and surgical outcomes of thoracoscope-assisted surgical stabilization of rib fractures in severe chest trauma

Serious blunt chest trauma usually induces hemothorax, pneumothorax, and rib fractures. More studies have claimed that early video-assisted thoracoscopic surgery with surgical stabilization of rib fractures (SSRF) results in a good prognosis in patients with major trauma. This study aimed to verify the outcomes in patients with chest trauma whether SSRF was performed. Consecutive patients who were treated in a medical center in Taiwan, for traumatic events between January 2015 and June 2020, were retrospectively reviewed. This study focused on patients with major trauma and thoracic injuries, and they were divided into groups based on whether they received SSRF. We used electrical impedance tomography (EIT) to evaluate the change of ventilation conditions. Different scores used for the evaluation of trauma severity were also compared in this study. Among the 8396 patients who were included, 1529 (18.21%) had major trauma with injury severity score > 16 and were admitted to the intensive care unit initially. A total of 596 patients with chest trauma were admitted, of whom 519 (87%) survived. Younger age and a lower trauma score (including injury severity scale, new injury severity score, trauma and injury severity score, and revised trauma score) account for better survival rates. Moreover, 74 patients received SSRF. They had a shorter intensive care unit (ICU) stay (5.24, p = 0.045) and better performance in electrical impedance tomography (23.46, p < 0.001). In patients with major thoracic injury, older age and higher injury survival scale account for higher mortality rate. Effective surgical stabilization of rib fractures shortened the ICU stay and helped achieve better performance in EIT. Thoracoscope-assisted rib fixation is suggested in severe trauma cases.

Effectiveness of biological drying for citric acid dewatered sludge: Evaluating the impact of energy-efficient ventilation strategies

The effectiveness of dehydration and utilization processes for citric acid dewatered sludge is hampered by its high concentrations of polysaccharides, proteins, and water-binding properties of microbial extracellular polymers (EPS). This research explores the efficacy and mechanisms involved in extracting water from this type of sludge using biological drying technology, with varying rates of ventilation. Especially pertinent was the use of low ventilation rates as control variables. Our results suggest that a scheduled intermittent ventilation at lower rates allows for the most efficient removal of water, achieving a rate of 41.71% within eight days, according to the zero-order kinetic model. Remarkably, the peak temperature registered was 60°C, reaching this threshold in just 0.1days and maintaining high temperatures for approximately 5.9days. Component analysis of organic matter illustrated a preferential degradation process for lipids under these ventilation conditions which is pivotal for releasing and transforming bound water for efficient extraction, as well as facilitating the breakdown of easily hydrolysable materials. Further, polysaccharide/protein (EPS) decomposition contributed to water removal, though less significantly. The periodic ventilation strategy allowed for the maximum cumulative temperature to be sustained, demonstrating superior efficiency in harnessing bio-generated heat (82.77% for water evaporation), resulting in dry sludge suitable for self-sustained combustion at relatively low cost ($26.61/t). Highlighted by this study is the considerable potential of energy-efficient ventilation methods in the biological drying treatment of citric acid fermented sludge and similar industrial waste materials.

Simulation-based suggestions for lockdown rules in dense urban areas considering indoor-outdoor droplet transmission under natural ventilation conditions

Simulation-based suggestions for lockdown rules in dense urban areas considering indoor-outdoor droplet transmission under natural ventilation conditions

Effects of adenoid hypertrophy on nasopharyngeal airway ventilation: A computational fluid dynamics study

Adenoid hypertrophy causes impaired nasopharyngeal airways (NA) ventilation. However, it is difficult to evaluate the ventilatory conditions of NA. Therefore, this study aimed to analyze the nasopharyngeal airway resistance (NARES) based on computational fluid dynamics simulations and the nasopharyngeal airway depth (NAD) and adenoid hypertrophy grade measured on cephalometric cone-beam computed tomography images and determine the relationship between NAD and grade and NARES to ultimately assess using cephalometric measurements whether NA has airway obstruction defects. Cephalogram images were generated from cone-beam computed tomography data of 102 children (41 boys; mean age: 9.14±1.43 years) who received orthodontic examinations at an orthodontic clinic from September 2012 to March 2023, and NAD and adenoid grade and NARES values were measured based on computational fluid dynamics analyses using a 3D NA model. Nonlinear regression analyses were used to evaluate the relationship between NARES and NAD and correlation coefficients to evaluate the relationship between grade and NARES. NARES was inversely proportional to the cube of NAD (R2=0.786, P<0.001), indicating a significant relationship between these variables. The resistance NARES increased substantially when the distance NAD was less than 5mm. However, adenoid Grade 4 (75% hypertrophy) was widely distributed. These study findings demonstrate that the ventilatory conditions of NA can be determined based on a simple evaluation of cephalogram images. An NAD of less than 5mm on cephalometric images results in NA obstruction with substantially increased airflow resistance.