Influence Of Atmospheric Pressure Research Articles

Influence of atmospheric pressure on the aging mechanism of LiCoO2/graphite cells

With the application of lithium-ion battery (LIB) in the field of electric aircraft, the aging behavior and mechanism of LIB under low-pressure environment have become an important topic. In this paper, the aging characteristics of LiCoO2/graphite cells under low pressure are investigated. The results show that the decrease of pressure leads to the degradation of cell capacity. With the pressure decreases from 96 kPa to 30 kPa, the capacity loss rate of the cell increases from 0.5 % to 17.4 %. Coulomb efficiency and differential voltage analysis indicate that low pressure accelerates the loss of lithium inventory. The X-ray computed tomography shows that the cell cycled under low pressure exhibits more significant deformation. The disassembly photos demonstrate that the side reactions of the cell are more obvious under low pressure. The scanning electron microscopy and elemental analysis results confirm that the thickness of solid electrolyte interface film increases with the decrease of pressure. These phenomena indicate that the intensification of battery deformation and internal side reactions under low pressure leads to a decrease in the electrochemical kinetics and long-term cycling ability of the battery.

The Influence of Atmospheric Pressure and Organic Loading on the Sustainability of Simultaneous Nitrification and Denitrification

In high-altitude regions, a diminished atmospheric oxygen content significantly impairs the aeration efficiency of municipal wastewater, posing a challenge to sustainable wastewater management. Consequently, conventional biological wastewater treatment methods necessitate elevated energy consumption in high-altitude areas, rendering them economically and environmentally unsustainable. The simultaneous nitrification and denitrification (SND) process, owing to its minimal oxygen requirements, emerges as a promising and sustainable solution in low-pressure environments. Additionally, owing to the unique lifestyle and natural conditions in plateau regions, the organic loading in municipal wastewater is often low. To comprehensively assess the impact of low pressure and organic loading on the SND process, three laboratory-scale reactors were implemented. This study revealed that low pressure and the introduction of organic matter enhanced both nitrogen removal performance and SND efficiency. The sludge volume index decreased by 93.5%, indicating a substantial improvement in the microbial aggregation ability and the formation of a more favorable SND sludge structure. 16S rRNA sequencing results demonstrated alterations in the microbial community structure due to low pressure and the addition of organic matter, leading to a substantial increase in the abundance of nitrifying and denitrifying bacteria. Furthermore, the prediction results of functional genes indicated the upregulation of genes related to the nitrification and denitrification processes with decreasing pressure and the addition of organic matter. This enhancement underlines the improved microbial nitrogen removal function. This study underscores the positive influence of low pressure and organic loading on the SND system, thereby substantially enhancing the economic and environmental sustainability of the SND process in plateau regions.

Growth of YBa2Cu3O7-δ superconducting films under different atmospheres by pulsed laser deposition

This paper aims to explore the epitaxial growth process for high-temperature superconducting YBa2Cu3O7-δ (YBCO) thin films by pulsed laser deposition (PLD) under different deposition atmospheres. The possibility of depositing YBCO superconducting thin films, under an oxygen-free environment, that was different from the oxygen atmosphere for most deposition processes of YBCO superconducting thin films was studied. Three different atmospheres, with oxygen, nitrous oxide, and nitrogen, were used in the experiment. The influence of atmospheric pressure on the formation and superconductivity of the YBCO phase were studied in detail. The characterization of structure and electrical properties of the thin films showed that YBCO thin films showed highly preferentially growth along the c-axis, had good superconductivity, and could be prepared under all three atmospheres. The formation of the YBCO phase at high temperatures did not need oxygen, and subsequent low-pressure oxygen-annealing process was only required at low temperatures of about 350 ℃. Our findings are of great significance for the preparation and application of YBCO thin films on substrates that were easy to oxidize at high temperatures, such as nickel strips or some electronic printed circuit boards.

Pre‐storage hypobaric treatment reduces microbial spoilage and maintains eating quality of strawberry fruits during low temperature conditions

Strawberry fruits are highly perishable and susceptible to microbial decay. In this study, influence of atmospheric pressure, postharvest delay in hypobaric treatment, and combined effect of pressure and exposure duration on storage quality of strawberries were evaluated. Treatment at 40 kPa for 4 h without postharvest delay inhibited fungal decay and retained visual quality which contributed to 13% increase in marketable life of strawberries compared with control. Further study revealed that microbial control and storage quality of strawberries treated either at 20 kPa for 2 h or 40 kPa for 4 h were statistically comparable. After 12 days, strawberries treated at 20 kPa for 2 h had 14.3% higher radical scavenging activity, 13.9% higher phenolic contents and 17.7% higher ascorbic acid than control fruits. Thus, pre-storage treatment at 20 kPa for 2 h without postharvest delay effectively retained fruit quality and extended storage life of strawberries for 6 more days compared with control. Novelty impact statement Hypobaric treatment is a potential non-chemical technique used to disinfect and extend storage life of strawberries. Results showed that hypobaric treatment at 20 kPa for 2 h without any postharvest delay can be adopted to disinfect strawberries from microbial infection and to extend marketable life. These findings may help in developing commercial hypobaric technology for perishable and decay-susceptible fruits and vegetables.

Compact Thermal Modeling of Power Semiconductor Devices with the Influence of Atmospheric Pressure

The efficiency of the heat dissipation process generated in semiconductor devices depends on many factors, related both to the parameters of the cooling system and environmental factors. Regarding the latter factors, ambient temperature and volume in which the device operates are typically indicated as the most important. However, in the case of the operation of semiconductor devices in non-standard conditions, e.g., in stratospheric airships, the thermal parameters of the device are significantly affected by a low value of atmospheric pressure. This paper presents a compact thermal model of a semiconductor device, considering the effects of reduced atmospheric pressure along with its experimental verification under various cooling conditions, thus obtaining high compliance for computation and measurement results. The formulated model is dedicated to circuit-level simulations, and it enables computations of the junction temperature of the semiconductor device in a short time. It is also shown that lowering atmospheric pressure can double the value of the junction-ambient thermal resistance.

The influence of atmospheric pressure on methane drainage from mines in the Upper Silesian Coal Basin

The influence of atmospheric pressure on methane drainage from mines in the Upper Silesian Coal Basin

Simulation Analysis of Pumping Characteristics for High-Altitude Concrete

AbstractTo investigate the characteristics of high-altitude concrete, the influences of atmospheric pressure on the air content, bubble stability, and pore structure of air-entrained concrete were ...

Methodology for calculating an atmospheric pressure-sensitive thermal comfort index PMVaps

Several software tools have been created to calculate the indices Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) by following Fanger’s method, which is valid only for atmospheric pressures close to 1 atm.The main objective of this work is to propose a formulation named PMV-PS for predicting an atmospheric pressure-sensitive thermal comfort index (PMVaps). The effort conducted by the authors was focused on the identification of the variables and expressions used in the calculation of thermal comfort index that may be affected by the change of the atmospheric pressure. The best known formulations for each individual aspect were introduced in the new model. It has been calibrated with data at sea level and tested for a set of cases considering different values of metabolic activity rate, thermal resistance of clothing and environmental parameters. At sea level there are negligible differences between PMV and PMVaps. However, when atmospheric pressure deviates from 1 atm, large differences between PMV and PMVaps are observed. PMV-PS model is a good starting point for further investigations into the influence of atmospheric pressure on thermal comfort perception and assessment, under real conditions, or using hypobaric chambers. Moreover, due to the subsisting doubts resulting from the analysis of published studies, it is crucial to perform further experimental work with high statistical significance i) to test the validity of the adopted correlations for the relationship between metabolic rate and atmospheric pressure and ii) to investigate in deep thermal comfort sensation of individuals used to live at altitude and of individuals with short-term exposure to an environment different from what they are used to live.Based upon the main findings of the present work, not considering the atmospheric pressure effect in PMV index may lead to significant errors.

The influence of atmospheric pressure on methane drainage from mines in the Upper Silesian Coal Basin

The influence of atmospheric pressure on methane drainage from mines in the Upper Silesian Coal Basin

Influence of atmospheric pressure and ambient temperature on the sub-floor of the San Ildefonso micro-basin Trujillo, Peru

En marzo del 2017 la Quebrada San Ildefonso, Trujillo, Peru, se activo como consecuencia de las precipitaciones pluviales generadas por el evento climatico denominado El Nino Costero 2017 impactando la infraestructura urbana en la trayectoria de su cauce. El presente estudio tuvo como objetivo demostrar la relacion existente entre los factores ambientales: presion atmosferica y temperatura ambiental en la fluctuacion del nivel freatico de la quebrada San Ildefonso determinando que la variacion de unos pocos hectopascales (hPa) de presion, asi como el incremento de la temperatura influyen en la fluctuacion del nivel freatico expuesto bajo la superficie del terreno. La metodologia consistio en la medicion de los parametros ambientales durante los anos 2018 y nivel de la napa freatica de un pozo artesiano en desuso ubicado en el cauce de la quebrada durante los meses de enero a julio 2019. Los datos fueron tomados desde la superficie del terreno hasta el nivel de agua dentro del pozo cada seis horas, acorde a la oscilacion maxima y minima de la marea barometrica; simultaneamente se registraron la temperatura de aire, del agua y suelo. Se concluye que la presion atmosferica y temperatura influyen en el ascenso y descenso diario del nivel del agua subterranea de la quebrada de San Ildefonso.

Spatiotemporal Relationships between Air Quality and Multiple Meteorological Parameters in 221 Chinese Cities

Air quality in China is characterized by significant spatial and temporal differences, which are directly related to local meteorological conditions. This study used air quality monitoring data, namely, the air pollution index (API) and air quality index (AQI) between 2005 and 2018, together with meteorological data and identified key meteorological factors that affected the spatial and temporal variation of air quality using a random forest algorithm. The spatial and temporal differences in the threshold values of different meteorological factors affecting the concentrations of PM2.5, PM10, SO2, CO, NO2, and O3 were identified. The AQI has the advantages of facilitating higher index values than the API. The air quality showed an improvement from 2005 to 2018. Wind direction and precipitation were the most important meteorological factors affecting the air quality in northern and southern China, respectively, which to some extent reflected the causes and degradation mechanisms of air pollution in the two regions. There were significant spatial and temporal differences in the effects of meteorological factors on the concentrations of different pollutants. The influence of atmospheric pressure on pollutant concentration differed between the east and west. Precipitation and relative humidity in most cities had significant impacts on PM2.5 and PM10. The influence of relative humidity was most significant for SO2 and it also had a great influence on O3, while wind speed had a great influence on NO2. The results of the study confirm the meteorological sensitivity of air quality and provide support for the implementation of regional air pollution prevention and control initiatives.

First Observations of Cosmic Ray Neutrons by a Mini Neutron Monitor at Riyadh, Saudi Arabia

In April 2017, a mini neutron monitor (NM) was installed at King Abdulaziz City for Science and Technology (KACST) central Saudi Arabia (Riyadh; cut-off rigidity, Rc = 14.4 Gv) for continuous observation of the cosmic ray (CR) neutrons. The detector was built as a major aspect of the international scientific joint effort between the Centre of Space Research (North-West University, Potchefstroom, South Africa) and KACST. The recorded data correspond to low energy neutrons that primarily have energies lower than 20 GeV. In this paper, a brief description about the mini NM detector will be given. The influence of atmospheric pressure on the recorded CR neutrons was studied and the barometric coefficient was calculated and used to eliminate the pressure effects from the measured data. The obtained coefficient was consistent with those previously obtained by several investigators. The daily variation of the CR neutron was studied and characterized. Short-term CR periodicities, such as the 27-day period, and its two harmonics, were identified. The obtained periodicities are in agreement with those reported by different researchers. The obtained results from this detector have been compared to the existing 1 m2 scintillator detector showing comparable results. Long-term data from this detector will be of incredible significance to the research community to investigate several types of CR variations resulting from solar activity at such high cut off rigidity site.

The Influence of Atmospheric Pressure on Air Content and Pore Structure of Air-entrained Concrete

To study the effect of atmospheric pressure on the properties of fresh and hardened air-entrained concrete, three kinds of air entraining agents were used for preparing air-entrained concrete in the plateaus (Lhasa, 61 kPa) and the plains (Beijing, 101 kPa). Air content, slump, compressive strength and pore structure of the three air-entrained concretes were tested in these two places. It is found that the air content of concrete under low atmospheric pressure (LAP) is 4%-36% lower than that of concrete under normal atmospheric pressure (NAP), which explaines the decrease of slump for air-entrained concrete under LAP. Pore number of hardened concrete under LAP is reduced by 48%-69%. While, the proportion of big pores (pore diameter >1 200 μm) and air void spacing factor are increased by 1.5%-7.3% and 51%-92%, respectively. The deterioration of pore structure results in a 3%-9% reduction in the compressive strength of concrete. From the results we have obtained, it can be concluded that the increase of critical nucleation energy of air bubbles and the decrease of volumetric compressibility coefficient of air in the concrete are responsible for the variation of air content and pore structure of concrete under LAP.

Study on the Properties of Aerodynamic Reference Sound Sources

Towards the establishment of traceability in sound power in airborne sound, the present study focuses on the dissemination procedure. Aerodynamic reference sound sources were studied as potential transfer standards. Initially, the sources were examined in the up-to-present requirements. The core of the study is the correction required for the transition from calibration to in situ conditions. The influence of atmospheric pressure, ambient temperature and fan rotation speed was investigated and the corresponding correction was determined. A comparison to an existing correction was also performed. Near field effects were another part of the study. The related uncertainty was estimated in a transparent approach. The dependency of the uncertainty on the in situ and calibration condition values is also presented.

Modeling the Splice Loss of Single-Mode Optical Fibers Affected by Altitude

Splicing loss of optical fibers has always been the focus of attention in engineering. With the construction of communication networks in high altitude areas, more attention has been paid to the fusion of optical fibers in high altitude areas. A mathematical model of single-mode optical fibers splice loss affected by altitude is established in this paper. The model takes the splice loss caused by the mismatch in mode field diameters (MFD), angular misalignment and lateral misalignment into account, as well as the influence of atmospheric pressure on splicing angular misalignment. Fiber fusion experiments are carried out at different altitudes. The proposed model is validated by the experimental results and can be used as a reference to future research on the splice loss of single-mode fibers in plateau areas.

Seasonal incidence of ruptured abdominal aortic aneurysm and the influence of atmospheric pressure: a systematic review and meta-analysis.

Ruptured abdominal aortic aneurysm (rAAA) is a life-threatening condition with a high mortality rate. Seasonal variations in the incidence of rAAA and the influence of atmospheric pressure have been studied throughout decades; however, the conclusions are contradictory. Therefore, we aimed to conduct a meta-analysis and systematic review of literature on seasonal variations in rAAA incidence and the influence of atmospheric pressure. Studies investigating seasonal variations in rAAA incidence and influence of atmospheric pressure were retrieved. For dichotomous data, we generated risk ratios (RRs) and 95% confidence intervals (CIs) for rAAA incidence compared among seasons. The studies were subdivided according to latitude, elevation, and climatic types, for subgroup comparisons. Studies reporting monthly incidence and seasonal mortality were further investigated. For continuous data, standardized mean differences (SMDs) and 95% CIs were generated for atmospheric pressure comparisons. Twenty-four eligible studies were included, comprising a total of 38,506 patients with rAAA. Pooled rAAA incidence was 25% in spring, 23% in summer, 26% in autumn, and 26% in winter. Pooled analysis demonstrated a statistically significant higher rAAA incidence in winter than in summer (RR 1.10, P = 0.04) and in autumn than in summer (RR 1.11, P < 0.00001). However, there was no statistically significant difference among other seasons. In the study of the influence of atmospheric pressure, no statistically significant difference was observed. In conclusion, our study revealed a higher incidence of rAAA in autumn and winter than in summer; however, atmospheric pressure was found to exert no influence.

Circulation flow rate and decarburization in the RH degasser under low atmospheric pressure

The pressure difference between the atmosphere and vacuum vessel is the driving force to make the molten steel to be suctioned into the RH vacuum vessel where decarburization occurs. The circulation flow rate of molten steel has a decisive influence on the decarburization efficiency. In this work, a VOF–DPM coupled model has been developed to investigate the multiphase flow in the RH degasser, and a decarburization model has been built to predict the variation of [C] in molten steel during degassing. Based on the created models, the influence of atmospheric pressure and snorkel immersed depth on circulation flow rate and decarburization has been clarified. The calculated circulation flow rate and decarburization rate agree well with the measured results. The result indicates that the decarburization of the RH degasser under low atmospheric pressure at high altitude will be significantly weakened due to that the drop of atmospheric pressure will remarkably decrease the circulation flow rate of molten steel. The snorkel immersed depth is suggested to be increased from 0.5 to 0.75 m to increase the circulation flow rate from 90.5 to 120.9 ton/min and thereby decrease the [C] in molten steel after degassing from 0.002–0.0023 wt% to 0.0014–0.0017 wt%.

The influence of atmospheric pressure on aortic aneurysm rupture--is the diameter of the aneurysm important?

The rate of aortic aneurysm rupture correlates with the aneurysm's diameter, and a higher rate of rupture is observed in patients with larger aneurysms. According to the literature, contradictory results concerning the relationship between atmospheric pressure and aneurysm size have been reported. In this paper, we assessed the influence of changes in atmospheric pressure on abdominal aneurysm ruptures in relationship to the aneurysm's size. The records of 223 patients with ruptured abdominal aneurysms were evaluated. All of the patients had been admitted to the department in the period 1997-2007 from the Silesia region. The atmospheric pressures on the day of the rupture and on the days both before the rupture and between the rupture events were compared. The size of the aneurysm was also considered in the analysis. There were no statistically significant differences in pressure between the days of rupture and the remainder of the days within an analysed period. The highest frequency of the admission of patients with a ruptured aortic aneurysm was observed during periods of winter and spring, when the highest mean values of atmospheric pressure were observed; however, this observation was not statistically confirmed. A statistically non-significant trend towards the higher rupture of large aneurysms (> 7 cm) was observed in the cases where the pressure increased between the day before the rupture and the day of the rupture. This trend was particularly pronounced in patients suffering from hypertension (p = 0.1). The results of this study do not support the hypothesis that there is a direct link between atmospheric pressure values and abdominal aortic aneurysm ruptures.

Influence of Atmospheric Pressure Guided Streamers (Plasma Bullets) on the Working Gas Pattern in Air

This paper is devoted to the study of gas flow fields related to helium atmospheric pressure guided streamer (plasma bullet) propagation in the air. For very weak up to moderate helium flows, the modification induced to the gas flow field by the plasma ignition is demonstrated; it is shown that the turbulent flow region is expanded and two conditions must be fulfilled regarding the working gas profile in the air for streamer propagation, i.e., laminar flow and high concentration in this laminar flow region. © 2014 IEEE.

Influence of Atmospheric Pressure on the Incidence of Spontaneous Pneumothorax

BackgroundThis study analyses the relationship between the incidence of idiopathic spontaneous pneumothorax (ISP) and atmospheric pressure (AP). MethodsA total of 288 cases of ISP were included, 229 men and 59 women. The AP of the day of diagnosis, of the 3 prior days and the monthly average were registered. The association between the incidence of ISP and AP was analyzed by calculating standardized incidence ratio (SIR) and Poisson regression. ResultsThe AP on the day of admission (mean±standard deviation) (1017.9±7 hectopascals [hPa]) was higher than the monthly average AP (1016.9±4.1hPa) (P=.005). There was a monthly distribution pattern of ISP with the highest incidence in the months of January, February and September and the lowest in April. When AP was less than 1014hPa, there were fewer cases registered than what would statistically have been expected (58/72 cases). In contrast, when the pressure was higher than 1019hPa, the registered cases were more than expected (109/82 cases) (SIR=1.25; 95% CI: 1.04–1.51). The risk of ISP increased 1.15 times (95% CI: 1.05–1.25, P=.001) for each hPa of AP, regardless of gender, age and monthly average AP. A dose–response relationship was observed, with progressive increases in risk (IRR=1.06 when the AP was 1014–1016hPa; 1.17hPa when the AP was 1016–1019hPa and 1.69 when the AP was superior to 1019hPa) (P for trend=.089). ConclusionAP is a risk factor for the onset of idiopathic spontaneous pneumothorax.