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Values of laminar burning velocity obtained by the constant volume method suffer from the inaccuracies introduced by the semi-analytical burned gas mass fraction model and flame stretch. A cylindrical combustion chamber with full optical access was developed in the present study, enabling the photography of the flame until the flame touches the inner wall of the combustion chamber. This enables direct visualization of the flame, thus eliminating the dependency on burned gas mass fraction models. The values of laminar burning velocity obtained by simultaneous measurement of flame radius and pressure-time data using the constant volume method are not stretch-free. This paper also develops a methodology for stretch correction based on the determined laminar burning velocity. Experiments were performed on mixtures of methane and air at initial pressures (0.8–1.05 bar), initial temperatures (293–320 K) and equivalence ratios (0.8–1.2). Stretch-corrected laminar burning velocity for lean, stoichiometric, and rich methane-air flames has been obtained in the present study, and the results obtained are validated against available experimental data and 1-D flame computations. It is expected that the proposed method significantly reduces the inaccuracies in laminar burning velocity obtained by the constant volume method. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effects of supraglottic airway tools such as classical laryngeal mask (cLMA) and I-gel, which can be used without the need for muscle relaxation in the airway management of general anesthesia patients, on the otolaryngeal system. Methods: This prospective randomised study was conducted at Karadeniz Technical University Hospital, Faculty of Medicine, Trabzon, Turkey, during November 2020 to December 2021. Eighty-nine patients in the American Society of Anesthesiologists (ASA) grade I-II group, who would undergo elective surgery under general anesthesia, were randomized into two groups, namely Group cLMA and Group I-gel. cLMA and I-gel were used for airway management of the patients. After anesthesia induction, tympanometric measurements were taken at regular intervals for middle ear pressures of both ears. Results: While air way pressures, SpO2 and EtCO2 values were within normal limits, there were no differences in terms of complications. In tympanometric measurements, middle ear pressure increase was statistically higher in the cLMA group than in the I-gel group (p <0.001). Conclusions: We think that I-gel may be a more advantageous supra glottic airway device in terms of otolaryngeal effecs and middle ear pressure in theair way management during short surgical procedures. [ABSTRACT FROM AUTHOR]

This study aims to study the changes in surface friction of flexible cavities produced by 3D printing under different internal pressures. An inflatable flexible air cavity fabricated using 3D printing technology and made of Tough-PLA and TPU95A materials was used as the experimental object. This study conducts low-speed friction tests on flexible surfaces under two conditions: different load pressure and different internal pressure. The experimental results show that under the same load conditions, the average sliding friction force between the contact surfaces with a contact area of only 16 cm2 increases by approximately 1 N as the air pressure increases, while the maximum static friction force increases by approximately 2–6 N. The inflatable cavity changes the friction of the contact surfaces under the influence of different internal air pressures. Through roughness measurements and microphotographs of the contact surfaces under different internal air pressures, it was found that the main reason is that the internal air pressure changes the surface roughness of the contact surface, thereby changing the friction between the contact surfaces. This study demonstrates a novel way to control the friction between flexible material contact surfaces. It has broad prospects and great significance for the future application of 3D printing flexible materials in the contact friction control of robot grippers and flexible joints and the lightweight of brakes. [ABSTRACT FROM AUTHOR]

Biodiesel has been chosen as a decent alternative to diesel in the context of establishing environmentally pleasant conditions and saving petroleum‐based resources for future generations. It is well‐established that biodiesel‐powered diesel engines may achieve outcomes equivalent to those of diesel engines. The current investigation was conducted to study the effect of injection pressure (190, 210, and 230 bar) and exhaust gas recirculation (EGR) (5%, 10%, and 15%) on a single‐cylinder variable compression ratio (VCR) diesel engine running using a B20 (20% MB + 80% PD) blend of microalgae biodiesel (MABD). This experiment was conducted in two stages. During the first stage of experimentation, the efficiency and emission characteristics of a diesel engine with a B20 blend of MABD at various fuel injection pressures and fresh air were investigated. During the second phase, fresh air was mixed with 5%, 10%, and 15% exhaust gases, and the experiment was conducted. It was discovered that increasing injection pressure to 230 bar provided considerable improvements. Brake thermal efficiency increased by 2.35%, brake‐specific fuel consumption decreased by 3.57% and pollutants such as carbon monoxide (CO), hydrocarbon, and smoke were reduced by more than 50% compared to conventional diesel. These reductions were similarly significant (over 22%) as compared to the B20 blend at lower injection pressure (210 bar). However, there was a slight trade‐off: nitrogen oxide (NOx) emissions increased partially (3.14%), while exhaust gas temperature (EGT) increased by 1.72% at a higher pressure. The study then investigated the influence of EGR (5%, 10%, and 15%) at various injection pressures. The optimal value seems to be 10% EGR at 230 bar injection pressure. This combination substantially reduced NOx emissions (by over 41% compared to the normal B20 blend) and EGT (by more than 8%), while having no notable effect on other performance or emission variables. Overall, the results show that employing a B20 MABD blend with high injection pressure (230 bar) and moderate EGR (10%) improves engine performance while reducing hazardous emissions. [ABSTRACT FROM AUTHOR]

Due to their exceptional impact resistance, ceramics are extensively used in various fields. However, unavoidable pores, microcracks, and inherent defects can degrade the performance of ceramic materials. A damage model of SiC ceramics under passive confining pressure was constructed based on the Lemaitre strain equivalence principle and the Weibull distribution function. This paper presented a dynamic damage model for SiC ceramics subjected to passive confinement pressure based on the principles of damage mechanics. Additionally, the split Hopkinson pressure bar device was employed to investigate the compressive strength and damage evolution of SiC ceramics at various shock pressures and confinement degrees. The experimental results indicate that constraints can reduce the damage to ceramics. The metal sleeve increased stiffness when compressing the ceramic material, allowing the specimen to convert from brittle–plastic–brittle. When sufficient constraints can be provided, the peak strain decreases gradually with the increase of the impact air pressure. Experimental data showing good agreement with the proposed model validated and analyzed the established model. Thinner boundary constraints cannot maintain the stability of ceramic structures, thicker boundaries do not significantly improve performance, and thicker boundaries can cause more weak areas. This paper provides guidance for the design of encapsulated ceramic composite armor by quantitatively studying the constraint thickness. [ABSTRACT FROM AUTHOR]

Flexible contact gasket is a significant component affecting the sealing performance of the refrigerator. However, few studies were conducted on the permeability characteristics of moist air through refrigerator gaskets. The purpose of this study is to explore the permeability characteristics including permeation paths size, flow type, modeling and temperature-humidity-pressure-structure effect. The characteristic scale of the interface of permeation paths is observed as 10−5 m in the free-state by atomic force microscope. The equation of Knudsen number and contact stress relation is established to judgment the flow types. By comparing the critical and simulated contact stresses, it is inferred that moist air simultaneously occurs slip, transition and free-molecular flows. A multi-scale coupling model of permeation rate is constructed to obtain the apparent permeability coefficient characterizing the permeability intensity. The air pressure difference affects the permeability characteristics in the form of direct driving force and changing the contact stress of the interfaces. Free-molecular flow mainly occurs under the negative pressure condition with inhalation coefficient of 2.26 × 10−5∼2.84 × 10−5 m2, while the slip flow mainly occurs under the positive pressure conditions with exhalation coefficient of 2.87 × 10−5∼4.65 × 10−5 m2. The essence of enhancing the sealing performance of structural improvement is to increase the contact stress and length of permeation path. By increasing the height, increasing the inclination angle, adding the auxiliary edges and adding an auxiliary airbag, the inhalation coefficient of moist air, the exhalation coefficient of moist air and the inhalation coefficient of water vapor are decreased by 54.82 %, 51.46 % and 66.04 %. [ABSTRACT FROM AUTHOR]

Hydroxylamine nitrate (HAN)-based liquid propellants are characterized by high energy content and low toxicity ionic monopropellants, offering great potential application prospects in the space engine. This paper proposes an experimental system for electric ignition and combustion of HAN-based liquid propellant. The energy for decomposition, current, and combustion image of HAN-based liquid propellant are measured under different initial voltage, propellant volume, and the initial pressures in Ar and air atmospheres. The results show that the energy for decomposition decreased with an increase in initial voltage, propellant volume, and initial pressure. An increase in the initial voltage accelerates the reaction speed of HAN-based liquid propellant, and the energy for decomposition is approximately 3 J. An increase in the propellant volume decreases the equivalent resistance in the circuit, increasing the current and enhancing the thermal effect of the propellant. The accumulation of decomposition products and heat under high pressure reduced the energy for decomposition; the energy for decomposition is less than 1.5 J for the pressurization condition. Compared with the Ar atmosphere, the energy for decomposition of HAN-based liquid propellant shows better stability in the air atmosphere. The flow combustion device of HAN-based liquid propellant for the flow state is designed. The HAN-based liquid propellant is successfully ignited for different initial voltages and flow rates. The research results provide a reference for the design of space engine for HAN-based liquid propellant based on the electric ignition method. • Experiments for HAN electric ignition on different initial U , V , P were carried out. • The effects of initial conditions on the ignition energy of HAN was studied. • The comparison of ignition energy in air atmosphere and Ar atmosphere was analyzed. • The propellant flow combustion based-on the electric ignition method was achieved. [ABSTRACT FROM AUTHOR]

Globally, the encouragement of using renewable fuels like biodiesel for diesel engines is driven by concerns over the fossil fuel depletion and harmful emissions. Additionally, the utilization of renewable fuel additives like diethyl ether has the potential to enhance fuel properties and boost engine performance. The aim of this paper was to construct a computer simulation using Ricardo Wave program in order to predict the performance and nitrogen oxides (NOx) emission of a diesel engine fuelled by a diesel‐biodiesel blend and a diethyl ether (DEE) as a fuel additive. The computer model was validated by comparing the simulation engine performance and NOx emission results against the corresponding experimental data for diesel, diesel‐biodiesel blend with 30% biodiesel proportion (B30), and two blends of diesel‐biodiesel‐DEE with DEE proportions of 5% and 10% on a volume basis. Also, the effect of varying the inlet air pressure on engine performance and NOx emission was compared for all investigated fuels. It was numerically demonstrated that using the DEE with an optimum proportion of 5% enhanced engine performance as it decreased engine fuel consumption by 5.9% and increased engine thermal efficiency by 9.6% compared to diesel fuel at engine full load condition. Also, a significant reduction of 20.5% in NOx emission resulted from the addition of DEE. Increasing the inlet air pressure increased engine power and decreased engine fuel consumption for all investigated fuels. Increasing the inlet air pressure from 1 to 3 bar increased engine brake thermal efficiency by almost 20% for all tested fuels. However, NOx emission increased slightly within a range from 1.7% to 7% for the different investigated fuels. [ABSTRACT FROM AUTHOR]

Climate change is considered one of the main challenges in this century, and CO2 emissions significantly cause it. Integrating CO2 capture, storage, and conversion is proposed to solve this problem. 1-Butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid was employed to capture and store CO2 from the air and subsequently converted into CO using non-thermal plasma. Moreover, we also tested the CO2 capture and storage capacity of water from different sources, e.g., Milli-Q, deionized water, and tap water. [Bmim]Cl solution captured CO2 from the air and then converted to CO after 24 h using plasma. In comparison with water (Milli-Q water, deionized water, and tap water), CO production was increased by 28.31% in the presence of water (Milli-Q water, deionized water, and tap water) + [Bmim]Cl. It suggests that this method could be a promising way to capture, store, and convert CO2 from air at atmospheric pressure and room temperature as an effort to reduce carbon emission. [ABSTRACT FROM AUTHOR]

A numerical investigation of a glow-type discharge in humid air with a water-cathode is reported. A complete block of chemical reactions that self-consistently describes the ionic composition of the plasma is considered. A water molar fraction up to 20% is examined. The electric field strength, emission discharge radius, as well as the OH (A → X) band emission in the positive column was also measured for discharge currents up to 155 mA. The model shows a non-thermal plasma with lower gas temperatures (around 3500 K) than those typically obtained in similar discharges but operating with metal electrodes in dry air. The gas temperature is almost unaffected by the discharge current. The vibrational relaxation through N2–H2O collisions is the main gas heating mechanism. The thermal diffusion due to enhanced thermal conductivity by water vapor is the primary cooling mechanism. The electron temperature is around 1 eV to ensure that the electron losses (mainly by dissociative recombination of NO+) are compensated by ionization phenomena. The NO+ is the dominant ion, mainly formed by electron-impact ionization of NO molecules. An electron number density close to 1019 m−3 is obtained. For the upper water fraction, the electron-impact ionization of O2 molecules, followed by a quick conversion to NO+, also plays a role. The concentration of OH is ~ 1022 m−3. A comparison between the model results and the experimental data suggests that the molar fraction of water in the plasma is around 20% for the conditions considered. [ABSTRACT FROM AUTHOR]

The phenomenon of liquid sloshing inside partially filled tank trucks adversely affects the stability of the tank trucks. In order to mitigate the negative effects of liquid sloshing inside the tank, this study proposes several baffle configurations and investigates their anti-slosh effect on liquid sloshing. First, a numerical model of liquid sloshing is established. Then, the effectiveness of the numerical model is validated by comparing the results of free surface deformation, wall pressure, and sloshing frequency obtained from simulations and experiments under identical conditions. During the research process, it was found that the air pressure formed in locally sealed spaces within the tank also plays a positive role in suppressing liquid sloshing. The research results indicate that, under low fill volumes, baffles fixed at the bottom of the tank are more effective in suppressing liquid sloshing inside the tank, while under high fill volumes, baffles fixed at the top of the tank are more effective. Considering the tank's airtightness, the air pressure formed in locally sealed spaces within the tank plays an important role in suppressing liquid sloshing when baffles are fixed at the top of the tank and the fill volume is high. [ABSTRACT FROM AUTHOR]

This study analyzes the influence of air curtain diameter and internal duct structure on the uniformity of an air curtain using Fluent numerical simulation combined with an experimental method after actual measurement of relevant parameters at the construction site, and simulates the best dust insulation parameters of a uniform air curtain. As the diameter of the air curtain supply duct increases and the internal air duct structure is reasonably designed, the axial static pressure of the air curtain generator and the air velocity at the curtain outlet are more uniform, which forms a higher strength of the air curtain. The best dust separation parameter of the uniform air curtain is the vertical downward generated air curtain with an outlet air velocity of 12 m/s and an outlet strip slit width of 80 mm, in which the dust separation efficiency could reach about 79.5%. [ABSTRACT FROM AUTHOR]

Highlights To achieve the wave‐transparent and anti/de‐icing requirements of electromagnetic functional structural components on the windward surface of the aircraft, the PTFE capillary hot air tubes were pre‐buried inside the quartz fiber cloth and the hot air anti/de‐icing quartz fiber/PTFE capillary/epoxy resin (QF/PTFE/EP) composite components was prepared to that met the wave‐transparent performance. A multi‐field coupled numerical finite element simulation model was established, and the anti/de‐icing performance of the QF/PTFE/EP composite with different built‐in tube diameters were investigated by combining experiments and simulations under different hot air temperatures and pressures. The feasibility of hot air anti/de‐icing was verified through anti/de‐icing experiments and numerical simulation. The electromagnetic transmittance of the prepared hot air anti/de‐icing QF/PTFE/EP composite components was tested to characterize the effect on the stealth performance of the aircraft under the service environment. The experimental results demonstrated that with 5 mm tube pitch and hot air of 60°C ± 1°C, the surface temperature of the component with three tube diameters could reach more than 10°C. Furthermore, the decrease in the transmittance of the hot air anti/de‐icing QF/PTFE/EP composite components caused by different incidence angles and two polarization modes was less than 3%. The hot air QF/PTFE/EP anti/de‐icing composite components were fabricated. The heat transfer, anti/de‐icing, and electromagnetic transmittance performance of the hot air QF/PTFE/EP anti/de‐icing QF/PTFE/EP components were investigated. The experimental and simulation results verified the hot air anti/de‐icing QF/PTFE/EP components met the requirement of aircraft anti/de‐icing and wave transmission. [ABSTRACT FROM AUTHOR]

Ion wind propulsion systems have potential applications in the field of unmanned aerial vehicle due to their compactness, quiet operation, and simple design. Previous studies have focused on the influences of power source, electrode arrangement, size, and shape on the output thrust characteristics. However, few studies have been performed on the environmental conditions, which can be beneficial for the practical applications of ion wind aircraft in various climatic conditions. In this work, a measurement platform of the output characteristics of ion wind propulsion system under various environmental conditions has been established. The experimental pressure range was 1–0.7 atm, and the relative humidity (RH) range was 30%–92%. The effects of air pressure and humidity, and voltage level on the thrust, thrust-to-power radio (TPR) corona current have been investigated. The results showed that the corona current and thrust of the wire-wing electrode array decreased with RH within the range of 30%– to 80%. Under higher humidity, the corona current and thrust tend to increase at most voltage levels. Moreover, the thrust and current both decreased with reduced pressure when keeping the voltage-to-pressure ratio (U/P) unchanged. It was also found that the thrust was roughly proportional to the square of the pressure. Finally, the possible explanations of the coupled influences on the output characteristics were discussed. [ABSTRACT FROM AUTHOR]

This study introduces a novel predictive model for atomization droplet size, developed using comprehensive data collected under elevated temperature and pressure conditions using a twin swirl airblast nozzle. The model, grounded in flow instability theory, has been meticulously parameterized using the Particle Swarm Optimization (PSO) algorithm. Through rigorous analysis, including analysis of variance (ANOVA), the model has demonstrated robust reliability and precision, with a maximum relative error of 19.3% and an average relative error of 6.8%. Compared to the classical atomization model by Rizkalla and Lefebvre, this model leverages theoretical insights and incorporates a range of interacting variables, enhancing its applicability and accuracy. Spearman correlation analysis reveals that air pressure and the air pressure drop ratio significantly negatively impact droplet size, whereas the fuel–air ratio (FAR) shows a positive correlation. Experimental validation at ambient conditions shows that the model is applicable with a reliability threshold of We1/Re1 ≥ 0.13 and highlights the predominance of the pressure swirl mechanism over aerodynamic atomization at higher fuel flow rates (q > 1.25 kg/h). This research effectively bridges theoretical and practical perspectives, offering critical insights for the optimization of airblast nozzle design. [ABSTRACT FROM AUTHOR]

Instead of the expected 3.8–5.4% increase in the heat transfer coefficient due to the better thermal conductivity of silicon carbide tubes compared to glass tubes, the observed increase was 18–22% for 150–275 kg·h−1 airflow and 6 kg·s−1 propane-1,2-diol coolant in tubes. This additional 15–17% increase is probably due to local flow turbulisation due to the roughness of the sintered carbide of 4–10 µm, which unfortunately also causes a 17–24% higher air pressure drop. The hand calculation model used underestimates the heat transfer coefficient by −2% to 10%, which is better than CHEMCAD 8 modeling results. [ABSTRACT FROM AUTHOR]

Fruit photosynthesis occurs in an internal microenvironment seldom encountered by a leaf (hypoxic and extremely CO2-enriched) due to its metabolic and anatomical features. In this study, the anatomical and photosynthetic traits of fully exposed green fruits of Quercus coccifera L. were assessed during the period of fruit production (summer) and compared to their leaf counterparts. Our results indicate that leaf photosynthesis, transpiration and stomatal conductance drastically reduced during the summer drought, while they recovered significantly after the autumnal rainfalls. In acorns, gas exchange with the surrounding atmosphere is hindered by the complete absence of stomata; hence, credible CO2 uptake measurements could not be applied in the field. The linear electron transport rates (ETRs) in ambient air were similar in intact leaves and pericarps (i.e., when the physiological internal atmosphere of each tissue is maintained), while the leaf NPQ was significantly higher, indicating enhanced needs for harmless energy dissipation. The ETR measurements performed on leaf and pericarp discs at different CO2/O2 partial pressures in the supplied air mixture revealed that pericarps displayed significantly lower values at ambient gas levels, yet they increased by ~45% under high CO2/O2 ratios (i.e., at gas concentrations simulating the fruit's interior). Concomitantly, NPQ declined gradually in both tissues as the CO2/O2 ratio increased, yet the decrease was more pronounced in pericarps. Furthermore, net CO2 assimilation rates for both leaf and pericarp segments were low in ambient air and increased almost equally at high CO2, while pericarps exhibited significantly higher respiration. It is suggested that during summer, when leaves suffer from photoinhibition, acorns could contribute to the overall carbon balance, through the re-assimilation of respiratory CO2, thereby reducing the reproductive cost. [ABSTRACT FROM AUTHOR]

Biomimetic actuation technologies with high muscle strokes, cycle rates, and work capacities are necessary for robotic systems. We present a muscle type that operates based on changes in muscle stiffness caused by volume expansion. This muscle is created by coiling a mechanically strong braid, in which an elastomer hollow tube is adhesively attached inside. We show that the muscle reversibly contracts by 47.3% when driven by an oscillating input air pressure of 120 kilopascals at 10 Hz. It generates a maximum power density of 3.0 W/g and demonstrates a mechanical contractile efficiency of 74%. The muscle's low-pressure operation allowed for portable, thermal pneumatical actuation. Moreover, the muscle demonstrated bipolar actuation, wherein internal pressure leads to muscle length expansion if the initial muscle length is compressed and contraction if the muscle is not compressed. Modeling indicates that muscle expansion significantly alters its stiffness, which causes muscle actuation. We demonstrate the utility of BCMs for fast running and climbing robots. [ABSTRACT FROM AUTHOR]

Background: This hypothesis introduces pump shoes as a method for the prevention and treatment of varicose veins. Method: An air pump is placed in the shoe, connected to an airbag wrapped around the leg through a hose. With each step, air is pumped into the foot airbag, applying pressure to the leg muscles and superficial veins. This action mimics muscle pumping, helping to push blood back towards the heart. Excess air is released through an outlet hose with an adjustable sphincter, allowing for increased pressure on the leg. Results & Conclusion: These shoes offer a simple mechanism to assist in returning blood from the feet to the heart. They can be beneficial in preventing varicose veins in at-risk individuals or treating those in the early stages of the disease. [ABSTRACT FROM AUTHOR]

Ultra-high-strength steels have been considered an essential material for aviation components owing to their excellent mechanical properties and superior fatigue resistance. When machining these steels, severe tool wear frequently results in poor surface quality and low machining efficiency, which is intimately linked to the friction behavior at the tool–workpiece interface. To enhance the service life of tools, the adoption of efficient cooling methods is paramount. However, the understanding of friction behavior at the tool–workpiece interface under varying cooling conditions remains limited. In this work, both air atomization of cutting fluid (AACF) and ultrasonic atomization of cutting fluid (UACF) were employed, and their spray characteristic parameters, including droplet size distribution, droplet number density, and droplet velocity, were evaluated under different air pressures. Discontinuous sliding tests were conducted on the ultra-high-strength steel against cemented carbide and the effect of spray characteristic parameters on the adhesion friction coefficient was studied. The results reveal that ultrasonic atomization significantly improved the uniformity of droplet size distribution. An increase in air pressure resulted in an increase in both droplet number density and droplet velocity under both AACF and UACF conditions. Furthermore, the thickness of the liquid film was strongly dependent on the spray characteristic parameters. Additionally, UACF exhibited a reduction of 4.7% to 9.8% in adhesion friction coefficient compared to AACF. UACF provided the appropriate combination of spray characteristic parameters, causing an increased thickness of the liquid film, which subsequently exerted a positive impact on reducing the adhesion friction coefficient. [ABSTRACT FROM AUTHOR]

In the rapid development of air pollution over the past two decades in Shandong Province, it has played a detrimental role, causing severe damage to regional ecological security and public health. There has been little research at the county scale to explore the spatiotemporal causes and heterogeneity of PM2.5 pollution. This study utilizes a Geographically and Temporally Weighted Regression Model (GTWR) to environmentally model meteorological elements and socioeconomic conditions in Shandong Province from 2000 to 2020, aiming to identify the key driving factors of PM2.5 concentration changes across 136 counties. The results show that PM2.5 pollution in Shandong Province peaked in 2013, followed by a rapid decline in pollution levels. Geographically, counties in the western plains of Shandong generally exhibit higher pollution levels, while most counties in the central hills of Shandong and the Jiaodong Peninsula are in low pollution areas. Strong winds positively influence air quality in the southeast of Shandong; high temperatures can ameliorate air pollution in areas outside the southeast, whereas air pressure exhibits the opposite effect. Precipitation shows a significant negative correlation in the Laizhou Bay and central Shandong regions, while relative humidity primarily exerts a negative effect in coastal areas. The impact of fractional vegetation cover is relatively mild, with positive effects observed in southern Shandong and negative effects in other regions. Population density shows a significant positive correlation in the western plains of Shandong. Economic factors exhibit predominantly positive relationships, particularly in the northwest and the Jiaodong Peninsula. Electricity consumption in southern Shandong correlates positively, while industrial factors show positive effects province-wide. PM2.5 pollution in Shandong Province demonstrates significant spatiotemporal heterogeneity, aligning with governmental expectations for the effectiveness of air pollution control measures. The conclusions of this study can be utilized to assess the efficiency of air pollution abatement at the county level and provide quantitative data support for the revision of regional emission reduction policies. [ABSTRACT FROM AUTHOR]

A theoretical study was conducted to investigate the cross-sectional configurations and the tensile forces of an air-inflated rubber dam anchored on the sidewall of the rigid base. A series of large-scale model tests were conducted using rubber dam models with a cross-sectional perimeter of 1.0 m and a length of 8.5 m. The results obtained from the analytical solutions agree well with those obtained from model tests. It is found that there is an optimum height of the rubber dam, especially for larger anchor depth with the increase of the inflated air pressure. The smaller the anchoring depth the higher the optimum inflated air pressure. The contact length between the rubber dam and the rigid base gradually decreases with the increasing inflated air pressure. The greater the anchor depth, the faster the contact length decreases to zero. Generally, the tensile force linearly increases with the increase of the normalized air pressure and the decrease of the anchor depth. • Theory was derived to calculate an air-inflated rubber dam anchored on the sidewall of rigid base. • A series of large-scale model tests were conducted to verify accuracy of the theoretical model. • Effects of upstream water levels, inflated air pressures and anchor depths were analyzed. [ABSTRACT FROM AUTHOR]

Vat photopolymerization (VPP) technology allows for the direct formation of complex structural Si 3 N 4 components, without the constraints of moulds, which is an emerging process for the preparation of Si 3 N 4 ceramics. However, the low curing depth makes it difficult to prepare Si 3 N 4 ceramics by VPP. To address this issue, the study proposes coating Si 3 N 4 particles with thermosetting resin. The UV absorption of the modified composite powder were reduced. The thermosetting resin could be removed during the debinding process without introducing impurities, which has minimal impact on the properties of the Si 3 N 4 parts. The study investigated the impact of E51 coating modification on the phopopolymerization of Si 3 N 4 slurries, and the mechanical properties after sintering. Moreover, the peak flexural strength and density of Si 3 N 4 prepared from modified Si 3 N 4 using VPP technology combined with air pressure liquid-phase sintering process were 382.67 MPa and 2.95 ± 0.02 g/cm3, respectively, at 2 wt% of E51 coating. [ABSTRACT FROM AUTHOR]

Blockages in sewers and drains often result in overflows and flooding that cause significant environmental pollution and public health risks, particularly in hospitals, where the consequences can be catastrophic. Due to their low "visibility", sewers and drains are inherently difficult to monitor and maintain, resulting in a reactive management approach whereby maintenance or repair is carried out only after a system failure has occurred. This paper investigates the feasibility of applying the reflected wave technique, a unique sonar-like monitoring approach capable of identifying changes in the geometry of closed-pipe conduits, as a means of proactive system monitoring. The technique uses a 10 Hz sinusoidal air pressure wave which is transmitted into the drainpipe. When the pressure wave encounters a system boundary, a reflection is generated which alters the measured test pressure response. Analysis of the reflections generated by a changed system boundary, such as the formation of a blockage, can provide information related to the location of that boundary within the system. An experimental setup was developed to simulate a horizontal drain using standard pipework of 100 mm diameter and 70 m length. The technique was able to detect applied blockages with cross-sectional coverage of 30% and 75%, and lengths ranging from 30 mm to 3000 mm. Accuracy was improved when the pressure sensor was positioned closer to the blockage. When the sensor was 3.4 m from the blockage, location estimates were very accurate (−2% to 3% error). At a 14 m distance from the blockage, the error increased to between 4% and 33%. The accuracy of blockage detection and location improved with increasing blockage cross-sectional area and length. Overall, the reflected wave technique could provide a potentially continuous monitoring solution for blockage detection in sewers and drains. [ABSTRACT FROM AUTHOR]

In order to obtain information regarding changes in the air cushion flow field and load-bearing characteristics of a single row hole air cushion belt conveyor, a structural model of the air cushion of the belt conveyor was established, with the single row hole air cushion belt conveyor as the research object. Firstly, according to the theory of fluid lubrication, a mathematical model of the air cushion was established. Then, the effects of air cushion thickness, pore velocity, and belt velocity on the pressure and bearing characteristics of the air cushion flow field were studied using FLUENT software. In addition, the equivalent stress, displacement, and pressure curves between the air cushion flow field and the conveyor belt and the material were analyzed using the two-way fluid–solid coupling method. Finally, the experimental platform of a single row hole air cushion belt conveyor was built, and the flow field and bearing characteristics of the belt were verified through experiments. The results show that reducing the thickness of the air cushion and increasing the pore flow rate can improve the pressure and bearing characteristics of the air cushion, while speed has little effect at lower belt speeds. [ABSTRACT FROM AUTHOR]

In grasping operations, when facing unstructured environments, the use of soft-body grippers can be a good solution to the problem of grasping objects that are inconvenient to grasp due to their fragility and irregularity. However, as the soft-body gripper is composed of soft-body material, there are problems such as insufficient gripping power. The envelope-gripping method using a fingerless structure of the soft gripper has high gripping capacity. In this paper, a new type of pneumatic, soft-body, fingerless gripper (SFLG) is proposed based on envelope-type grasping. With its rigid connectors, it forms a soft-body gripper. By changing the air pressure and structure of the internal air cavity of the fingerless gripper, the degree of deformation can be controlled to achieve grasping of the object by the soft-body gripper. Experiments show that the soft-body gripper can grasp objects of different shapes and sizes. The SFLG can grasp objects up to 6 times higher than itself, and the soft gripper of this size can grasp objects up to 13 times heavier than itself. A pneumatic, fingerless, soft gripper has been designed to grasp small and heavy or tall objects in contrast to other fingerless soft grippers. [ABSTRACT FROM AUTHOR]

In this study, a closed multi-channel air-blowing plug seedling pick-up device and a combined plug tray were designed to address the issues of complex structure, high seedling damage rates and low pick-up efficiency in fully automated vegetable transplanter systems. The device operates by sealing the plug seedlings in a seedling cup, where compressed air is channeled into the sealed cavity through multiple passages during the seedling pick-up process. The upper surface of the seedling plug is subjected to uniform force, overcoming the friction and adhesion between the plug seedlings and the tray. This process presses the seedlings into the guide tube, completing the pick-up operation. A mechanical model for the plug seedlings was developed, and the kinetics of the pick-up process were analyzed. The multi-channel high-pressure airflow was simulated and evaluated, identifying three key parameters affecting seedling pick-up performance: water content of the seedling plug, air pressure during pick-up, and air-blowing duration. Using these factors as variables, and with seedling pick-up rate and substrate loss rate as evaluation indicators, single-factor experiments and a three-factor, three-level orthogonal experiment were conducted. The experiments' results showed that the best seedling pick-up performance was achieved when the water content of the plug was 20%, the air pressure was 0.3 MPa, and the air-blowing time was 30 ms. Under these conditions, the seedling pick-up success rate was 97.22%, and the substrate loss rate was 10.46%. [ABSTRACT FROM AUTHOR]

Compared with the traditional "earth pressure balance" tunneling mode, the "air-pressure assisted" mode of shield tunneling has a more complex mechanism for maintaining excavation face balance, with significant differences in ground deformation and tunneling parameters compared to conventional full-chamber earth pressure balance tunneling mode. In order to quantitatively assess the stability of the excavation face under the air-pressure assisted tunneling mode and to determine a reasonable air-pressure setting, this study proposed an evaluation method for overall excavation face stability in the air-pressure assisted mode by using the limit equilibrium method, considering the spatial surface characteristics of the slip surface. Based on the Krabbe formula, considering the layering of the strata and the influence of groundwater, the formula for calculating gas loss was modified. In addition, a comparative tunneling test was conducted under different tunneling modes in the same strata condition, comparing the overall stability, air-pressure loss, ground settlement and tunneling parameters of the excavation face. The results showed that: according to the proposed overall stability evaluation method and the gas loss calculation method, the experimental section of this project met the overall stability requirements for air-pressure assisted tunneling. The selected air compressor had sufficient power for maintaining air-pressure stability in the strata, and the air-pressure setting met the requirements of engineering safety. Compared to the full-chamber earth pressure balance mode, the total thrust and cutterhead torque in the air-pressure assisted mode were reduced by 35% and 44%, respectively, while the advancing speed increased by 173% and energy consumption decreased by 66%. The air-pressure assisted tunneling mode resulted in a higher ground loss rate and relatively larger surface settlement. [ABSTRACT FROM AUTHOR]

Intumescent fireproof coatings protect steel structures and cables by forming a thick, fire-resistant layer under high temperatures. These coatings can deteriorate over time, impacting their fire resistance. Current testing methods are largely lab-based, lacking in-service evaluation platforms. Laser-Induced Breakdown Spectroscopy (LIBS) is emerging as a promising in situ detection technology but is influenced by low air pressure in high-altitude areas. This study investigates how air pressure affects LIBS signals in intumescent coatings on galvanized steel. Using pressures between 35 and 101 kPa, a linear model was developed to correlate laser pulses to ablation depth for characterizing coating thickness. Results show that spectral intensity decreases with lower air pressure. However, a strong linear relationship persists between laser pulses and ablation depth, with a fitting accuracy above 0.9. The coating thickness is identified by the number of laser pulses required to detect the Zn spectral line from the underlying galvanized steel. As air pressure decreases, the ablation depth increases. The study effectively models and corrects for air pressure effects on LIBS data, enabling its application for field detection of fireproof coatings. This advancement enhances the reliability of LIBS technology in assessing the fire performance of these materials, providing a reference for their in situ evaluation and ensuring better fire safety standards for building steel structures and cables. [ABSTRACT FROM AUTHOR]

Hydrogen is crucial for achieving SDGs by driving energy transition and combating climate change. Proton exchange membrane fuel cell technology, leveraging hydrogen, faces challenges in meeting high‐power demands. The multistack fuel cell system (MFCS) tackles this by integrating multiple substacks, yet its air supply needs meticulous control. Proportional integral derivative (PID) decoupling from single‐stack falls short of MFCS. This article proposes nonlinear model predictive control (NMPC) for optimized air flow and pressure decoupling. Modeling MFCS's air system and designing a predictive model, it is aimed to ensuring precise control of air flow and pressure in each substack. The decoupling experiments show that NMPC outperforms PID, accurately managing air flow and pressure and reducing load fluctuations. For air mass flow, NMPC cuts mean‐absolute error (MAE) by 64.56% and root‐mean‐square error (RMSE) by 81.36%. For pressure, MAE drops 81.23% and RMSE 83.59%. Comprehensive step load tests confirm NMPC's precise, dynamic regulation too, compared to PID, NMPC lowers average MAE for air mass by 20.67%, pressure by 32.22%. RMSE improvements of 31.08% and 33.23% highlight NMPC's strength. NMPC's quick response mitigates coupling issues, enhancing vehicle load adaptability. [ABSTRACT FROM AUTHOR]

Particulate matter from coal and stone operations is a primary air pollution source. The traditional nozzle requires high-pressure conditions, and the atomization droplets are large and uneven. This paper aims to study a linear Laval nozzle and investigate the impact of water pressure on atomization performance. The volume of fluid (VOF) model and discrete phase model (DPM) of Fluent are used to simulate the internal and external fields of the nozzle and analyze the velocity, droplet size, and atomization angle. The results show that the optimized water pressure parameters are 0.1 MPa with an air pressure of 0.5 MPa. Droplets in the middle are smaller, while those on the sides are larger. Compared to traditional nozzles, the water pressure is reduced by over 90%, and the Sauter mean diameter (SMD) decreases by over 50%. Moreover, the theoretical spray angle increases by approximately 150%. [ABSTRACT FROM AUTHOR]

To accurately predict the film thickness distribution during dynamic spraying performed with air guns and support accordingly the development of intelligent spray painting, the spray problem was analyzed numerically. In particular, the Eulerian-Eulerian approach was employed to calculate the paint atomization and film deposition process. Different spray heights, spray angles, spray gun movement speeds, spray trajectory curvature radii, and air pressure values were considered. Numerical simulation results indicate that the angle of spray painting significantly affects the velocity of droplets near the spray surface. With an increase in the spraying angle, spraying height and spray gun movement speed, the maximum film thickness decreases to varying degrees, and the uniformity of the film thickness also continuously worsens. When the spray gun moves along an arc trajectory, at smaller arc radii, the film thickness on the inside of the arc is slightly greater than that on the outside, but the impact on the maximum film thickness is minimal. Increasing air pressure expands the coating coverage area, results in finer atomization of paint droplets, and leads to a thinner and a more uniform paint film. However, if the pressure is too high, it can cause paint splattering. Using the orthogonal experimental method, multiple sets of simulation calculations were conducted, and the combined effects of spraying height, spray angle, and spray gun movement speed on the film thickness distribution were comprehensively analyzed to determine optimal configurations. Finally, the reliability of the numerical simulations was validated through dynamic spray painting experiments. [ABSTRACT FROM AUTHOR]

In this paper, a gas microbody is proposed to address the issues related to the limited load‐carrying capacity of squeezed film gas bearings, complex mechanical structures, large overall dimensions, high manufacturing costs, and complicated installation. Initially, the gas continuity equation of squeezed film was established for modal analysis, without regard to the gas inertial force and the gas volume force which are all far less than the gas viscous force. Then the load‐carrying characteristics of squeezed film gas bearing were studied and analyzed with the fluid‐structure coupling method. The load‐carrying capacity of the squeezed film gas bearing is determined by factors such as bearing amplitude, rotor‐axial clearance, and rotor‐axial tile contact area. In conclusion, the load‐carrying capacity can be enhanced by increasing the amplitude value, reducing the clearance, and increasing the contact area. Among them, when adjusting the amplitude and clearance to improve the bearing's load‐carrying capacity, the stability of bearing operation should be considered. When the clearance is too small, the pressure distribution of the air film will be uneven, and when the contact area is too large, the development of the air film in all directions will be asymmetrical. [ABSTRACT FROM AUTHOR]

ABSTRACT Existing solutions for electro‐osmotic consolidation assume a linear voltage distribution, which is inconsistent with the experimental findings. The present study introduces a novel two‐dimensional electro‐osmotic consolidation model for unsaturated soils, which considers the influence of non‐linear voltage distribution. The closed‐form solution is derived by employing the eigenfunction expansion method and the Laplace transform technique. The accuracy of the analytical solutions is validated through the implementation of finite element simulations. The findings from the parametric studies indicate that the excess pore water pressure (EPWP) observed in electro‐osmotic consolidation is influenced by the distribution of voltage. The dissipation rate of EPWP is observed to be higher when subjected to non‐linear voltage conditions compared to linear voltage conditions. Moreover, the impact of non‐linear voltage distribution becomes more pronounced in unsaturated soil characterised by higher electro‐osmosis conductivity and a lower ratio of kx/ky. In contrast, the excess pore air pressure (EPAP) remains unaffected by the voltage distribution. [ABSTRACT FROM AUTHOR]

Dewatering fine-grained materials is a common procedure in various industries. Nevertheless, the theory regarding the dewatering of fine-grained materials is largely confined to laboratory studies and some empirical and semi-empirical formulas. Most studies primarily concentrate on describing macroscopic phenomena. A positive pressure filtration device is introduced, and the effect of particle size during the process of filtration and dehydration is analyzed. The results show that the positive pressure horizontal filtration process is accompanied by interfering sedimentation, which results in the characteristic of a coarse filter cake at the lower part and a fine filter cake at the upper part. In the case of dewatering flotation coal filtration, high pressure assists in overcoming the adhesive force and surface tension of water, facilitating water discharge. The “air drainage” effect leads to variations in moisture levels in different parts. This study theoretically analyzes the positive pressure filtration sedimentation and its impact on particle size, the retention mechanism of capillary dewatering and coarse and heavy particles, as well as the air pressure dewatering mechanism. This study is of great significance for the design and development of new equipment for dewatering fine-grained materials with independent intellectual property rights. [ABSTRACT FROM AUTHOR]

The visual pressure chamber was designed. The pressure inside chamber can be measured and controlled. The camera can record the process of defoaming through the glass. To quantitatively study the relationship between defoaming rate and pressure, it is necessary to ensure that the morphology and size of the bubbles studied are basically the same. This article explores a bonding method of PET film that can control the diameter deviation of the bubbles within ±10 % for easy experimental comparison, while also eliminating bubbles through conventional processes without irreversible effects. The experiment found that below the critical pressure, the pores hardly undergo deformation. Above the critical pressure, the rate of pore contraction exhibits a positive correlation with the pressure. Through theoretical analysis, one mathematical model has been abstracted to represent the compression behavior of pores under pressure. In Abaqus, the simulation of the defoaming process was conducted using an explicit dynamic fluid cavity model. The simulated results obtained using the fluid cavity model in Abaqus are generally consistent with the experimental observations. When the film and bubbles are subjected to pressure, the film overcomes its own strength and undergoes a brief elastic deformation, and then begins a nonlinear change. At the same time, the internal space of the bubbles begins to shrink. When PET film is subjected to pressure, the deformation starts from the middle and gradually diffuses towards both sides. The internal air pressure of the bubbles increases until a state of mechanical equilibrium is reached. [ABSTRACT FROM AUTHOR]

The hard part turning process used to finish the cylindrical surfaces has some critical machining responses like tool wear with the lower quality of the machined surfaces. Minimum quantity lubrication (MQL)-based machining environment is currently considered an advanced cooling and lubrication technique. Cutting speed, feed rate, and cutting depth are considered input parameters, and the TaguchiL27 orthogonal array (OA) has been adopted as the design of the experiment. In this context, average surface roughness (Ra), tool flank wear (VBc), cutting temperature (T∘C), and chip morphology have been selected as measured outputs. To improve the machining performance of hardened steel, a sustainable MQL (flank+rake directions) cooling system has been employed at the cutting zone. Iron–aluminum LRT 30 was considered as the base fluid for the hard turning of AISI 4340 steel by PVD (AlTiN) and CVD (TiN/TiCN/Al2O3) coating cutting inserts. The primary effects of process parameters and their influences on the measured outputs have been discussed. The dual jet MQL-based hard turning was performed at three levels of cutting speeds (80, 170, and 260m/min), feed rate (0.5, 0.1, and 0.15mm/rev), and cutting depth (0.2, 0.3, and 0.4mm) with an air pressure of 5bar and mist flow rate 50ml/h. The findings showed that PVD-coated carbide tools outperformed CVD-coated tools. The model of the measured outputs of both tools has been developed using second-order regression analysis. Utilizing ANOVA analysis, all the predictive models were observed to be significant and acceptable with larger than 90% of R2 value. [ABSTRACT FROM AUTHOR]

Lasers are integral to numerous applications in our daily lives, with one of their notable uses being the ablation of materials to generate plasma, which in turn produces X-rays with a variety of applications. This study investigates the generation of hard X-rays from Aluminum Antimonide (AlSb) plasma, induced by a Q-switched Nd: YAG laser operating at 1064nm with a pulse duration of 9–14ns and a peak power of 1.1MW. The AlSb target was selected due to its unique electronic structure and high atomic number, which are advantageous for efficient X-ray generation. At a tight focus, the laser produced a spot size of 11.8 micrometers, achieving an intensity of 1012 W/cm−2, to study the transmission of hard X-rays both in a vacuum environment with a pressure of 10−3 torr and in air at atmospheric pressure. A Photo Multiplier Tube (PMT) was employed to detect the transmitted hard X-rays, which were filtered using a 10 μm-thick Al filter. The fundamental mechanisms behind the emission of hard X-rays from laser-induced AlSb plasma were explored. Plasma plume expansion and the energy of the emitted radiation were found to depend on the number of laser pulses and the ambient pressure. The intensity of the plasma plume was observed to be inversely proportional to the ambient pressure and directly proportional to the number of laser pulses fired. Plasma confinement under high pressures was also examined. Time-resolved studies of the hard X-ray emission contributed to the analysis. The relationship between different laser shots and the current, voltage, and energy of the hard X-rays, as well as their inverse proportionality to ambient pressure, was quantified. At an ambient pressure of 10−3 torr, the dynamics of the AlSb plasma plume were observed. The surface morphology of the laser-irradiated AlSb target was also analyzed, revealing unique properties pertinent to X-ray emission. [ABSTRACT FROM AUTHOR]

Translation abstract Lightweight ceiling elements made of carbon‐reinforced concreteIn concrete components under bending, a large proportion of the material used is underutilized. More material efficiency can be achieved, e. g., by resolving the solid interior of such components. In the presented project, this is realized by load‐bearing filigree carbon‐reinforced concrete membranes. At first, in the article, the method of producing such filigree structures by casting under negative air pressure is briefly explained and the material properties achieved in standard tests are discussed. Then, the design of two 1.8 m × 1.8 m large slabs and their load‐bearing behavior in 9‐point bending tests are described and compared with numerical simulations. Finally, an outlook on future research is given. [ABSTRACT FROM AUTHOR]

Automated water level measurements collected using vented pressure transducers in deep wells screened across the water table may exhibit a greater response to barometric pressure changes than the true water level. The cause was hypothesized to be disequilibrium in barometric pressure between the wellbores and land surface due to air exchange with the deep vadose zone. In this study, vented and nonvented pressure transducers were installed and operated simultaneously in two deep wells screened across the water table. A vent tube open to the atmosphere at land surface allowed for barometric compensation of the vented transducers. Two nonvented transducers were installed in each well, one submerged in the water and one above the water surface. The difference in readings allowed for barometric compensation. Manual measurements were also collected. It was confirmed that measurements from the vented transducers exhibited greater variability in response to barometric pressure changes than the nonvented transducers and manual measurements. Comparison of the downhole barometric pressure measurements to values from a nearby meteorology station showed the response in the wells to changes in barometric pressure was time‐lagged and attenuated. Thus, the reference pressure from land surface supplied to the vented transducers was not representative of the air pressure within the wells. This caused fluctuations of the transducer readings in response to barometric pressure changes to be greater than the true water level change. This issue can be resolved by the use of nonvented pressure transducers. [ABSTRACT FROM AUTHOR]

Nanosecond dielectric barrier discharge (NS-DBD) has emerged as a promising technique for controlling high-speed flows, generating a heated volume that generates strong density and viscosity gradients, thereby perturbing flow dynamics. Since its potential application in low-pressure, high-speed flows, understanding how the size and growth of the heated volume correlate with surrounding pressure is crucial. In this study, we employed typical schlieren and background-oriented schlieren (BOS) techniques to investigate the heated volume's sensitivity to surrounding pressure in quiescent air. The observed heated volume's size variations with surrounding pressure likely stemmed from the increase in thermal diffusivity at lower pressures. BOS findings unveiled a nearly linear decrease in heated volume's core density with energy input. Meanwhile, the heated volume's size augmented with energy input but exhibited gradual saturation, attributable possibly to shear stresses impeding volume expansion as temperature and viscosity rose, or to consumption of energy in vibration excitation and other reactions. In the cases of 100 and 50 kPa, the sensitivity of the heated volume's size to the reduced electric field appeared to be similar. However, at 10 kPa, where the reduced electric field is higher compared to that of the 100 and 50 kPa cases due to the lower air density, the size sensitivity drastically decreased. This suggested a transition in discharge mode from filamentary to diffusive behavior at lower pressures. [ABSTRACT FROM AUTHOR]

By utilizing top-of-atmosphere radiation (TOAR) data from China's new generation of geostationary satellites (FY-4A and FY-4B) along with interpretable machine learning models, near-surface particulate matter concentrations in China were estimated, achieving hourly temporal resolution, 4 km spatial resolution, and 100% spatial coverage. First, the cloudless TOAR data were matched and modeled with the solar radiation products from the ERA5 dataset to construct and estimate a fully covered TOAR dataset under assumed clear-sky conditions, which increased coverage from 20–30% to 100%. Subsequently, this dataset was applied to estimate particulate matter. The analysis demonstrated that the fully covered TOAR dataset (R2 = 0.83) performed better than the original cloudless dataset (R2 = 0.76). Additionally, using feature importance scores and SHAP values, the impact of meteorological factors and air mass trajectories on the increase in PM10 and PM2.5 during dust events were investigated. The analysis of haze events indicated that the main meteorological factors driving changes in particulate matter included air pressure, temperature, and boundary layer height. The particulate matter concentration products obtained using fully covered TOAR data exhibit high coverage and high spatiotemporal resolution. Combined with data-driven interpretable machine learning, they can effectively reveal the influencing factors of particulate matter in China. [ABSTRACT FROM AUTHOR]

The experiment aimed to compare different methods of measuring the Feed pellet durability through the effect of pellet die speeds and the particle size (mill sieve holes diameter). Feed pellet durability was studied in four different ways: pellet direct measurement (%), pellet lengths (%), pellet water absorption (%), pellet durability by drop box device (%), pellet durability by air pressure device (%). Three pellet die speeds 280, 300, and 320 rpm, three mill sieve holes diameter 2, 4, and 6 mm, have been used. The results showed that increasing the pellet die speeds from 280 to 300 then to 320 rpm led to a significant decrease in the feed pellet durability by direct measurement, drop box device, and air pressure device, while pellet water absorption a significant increased, whereas it did not significantly affect the pellet lengths. Increasing the sieve holes diameter from 2 to 4 then to 6 mm led to a significant decrease in the feed pellet durability in pellet lengths, drop box device, and air pressure device, pellet water absorption increased, whereas it did not significantly affect the direct measurement of pellet. Pellet die speeds of 280 rpm and the sieve holes diameter of 2 mm recorded the highest pellet durability for all ways: direct measurement 94.66 %, pellet lengths 85.94%, the drop box device 93.42% and the air pressure device 91.21%, less pellet water absorption 38.98 %. [ABSTRACT FROM AUTHOR]

The paper considers the results of a study on the oxidation kinetics of lead babbit B(PbSb15Sn10) with calcium in a temperature range of 373–473 K. In addition, the resulting oxidation products of alloys and their microstructure are examined. The studies were carried out using the thermogravimetric method in air at atmospheric pressure within the temperature range of 373–473 K. It was found that the oxidation process in the entire studied temperature range can be accurately described by a degree four polynomial. In the experiments, a variation in the oxidation rate was measured over time. The kinetic and energy parameters of the alloy oxidation process were determined. It was found that calcium additives increase the oxidability of the initial alloy B(PbSb15Sn10) in the temperature range of 373–473 K. It was demonstrated that the additives of the alloying component significantly alter the alloy microstructure. X‑ray diffraction analysis revealed that the oxidation products of lead babbit B(PbSb15Sn10) with 1.0 wt % calcium include the following oxides: Pb2Sn2O6; PbO; Sn2O4, SnO, Pb0.866O2, Sb2O5, Ca(Sb2O6), and Ca2Sb. [ABSTRACT FROM AUTHOR]

Wall deposition is the main problem in a spray dryer that affects the quality of the powder and decreases the dryer operation. In the current study, the influence of using an air pressure nozzle on the conical section of the dryer chamber was examined by simulation of flow pattern in a pilot plant spray dryer using computational fluid dynamics (CFD) technique and Ansys Fluent software (Ver. 17.0). The governing equations are solved in an axisymmetric geometrical model meshed by quadratic elements. Flow pattern was studied and compared in two conditions: before and after considering air pressure nozzle in the dryer chamber wall. Verification of velocity magnitude revealed that there was a little difference (5% to 7%) between numerical and experimental values and there was a good correlation (R²≥ 95%) between them. Flow pattern in the dryer chamber in absence of wall pressure nozzle showed recirculation zones were formed at the end of cylinder part of the chamber. Considering wall pressure nozzle in the model caused deflection of inflow towards the dryer wall and extension of chamber central core flow. The simulation results showed deviation of particle deposition from cone section towards the cylinder and ceiling parts of dryer. [ABSTRACT FROM AUTHOR]

In agriculture, machines engaged in various agrotechnical activities and operations have different impacts on the soil. The effect of mechanization is primarily reflected in two indicators: soil density and hardness. At the same time, considering the direct dependence of tractive resistance on soil hardness in processing machines and sprayers, we studied subsequent changes in the soil in the path of wheels affected by the soil after the passage of four-wheeled and three-wheeled tractors. We also examined various atmospheric pressures in the tractor's tires and the impact of different types of tires on soil compaction and traction. The studies showed that to reduce the compression impact on the soil of four-wheeled tractor working systems during certain technical operations, it is necessary to choose the maximum permissible travel speed and the minimum air pressure in the tires specified in the technical conditions. This approach helps to decrease soil compaction and maintain its structure. Additionally, it was found that three-wheeled tractors exert less pressure on the soil compared to four-wheeled ones, which should also be considered when selecting equipment for different agrotechnical tasks. Optimizing tire pressure and tractor speed is crucial for minimizing negative soil impact and enhancing the efficiency of agricultural operations. [ABSTRACT FROM AUTHOR]

Airlift pumps (ALPs) are promising in the oil and chemical industry, owing to their advantages such as a simple structure, convenient operation, wide applicability, high cost-effectiveness, environmental friendliness, safety, and reliability. However, there are few studies on the frictional pressure drop of vertically upward gas–liquid two-phase flow in ALPs. Therefore, this study presents an experimental investigation of the frictional pressure drop in the vertically upward gas–liquid two-phase flow in ALPs. Experiments were conducted in a vertical pipe with a total length of 3.245 m and a two-phase section of 2.8 m; the working pressure of the air compressor was 0.4 MPa, pipe diameter was 0.05 m, submergence ratio ranged from 0.6 to 0.85, and gas superficial velocity ranged from 0 to 4 m/s. A total of 74 sets of experimental data were obtained, and the frictional pressure drop models of 36 classical gas–liquid two-phase flows were evaluated. The results indicated that classical gas–liquid two-phase flow models significantly underestimated the experimental results. By analyzing the experimental data, visualizing the internal flow field, and performing theoretical derivations, a new frictional pressure drop correlation was established for the vertically upward gas–liquid two-phase flow in ALPs. The results demonstrated that the new model could accurately predict the frictional pressure drop of ALPs with mean percentage error, mean absolute percentage error, and root mean square percentage error values of 7.8%, 12.18%, and 25.86%, respectively. [ABSTRACT FROM AUTHOR]

The low drying rate is the main limitation of atmospheric freeze drying. The drying rate depends on the balance between heat and mass transfer. Among the process variables, air pressure changes have the opposite effects on heat and mass transfer simultaneously. The increase in pressure favors heat transfer but hinders mass transfer. Therefore, a conjugate model was proposed and validated to quantitatively investigate the heat and mass transport characteristics of lamellar products during freeze-drying in a tunnel under different pressures (1.325–101.325 kPa). To describe the effects of air pressure, the Navier-Stokes equations of the external fluid were coupled with the adsorption-sublimation model. Results show the regulation of transfer resistance values and drying rate with moisture content during the drying process, indicating that freeze-drying is the external heat transfer control at first, then the internal mass transfer control, and eventually, the heat transfer promotion can accelerate the process. The optimal constant pressure value was found to be 5.325 kPa, with the shortest drying time (17.3 h). It has been demonstrated that freeze drying employing a specific laddering-controlled strategy, offers the benefit of reducing drying time in comparison to the use of optimal constant pressure; however, the impact was not remarkable. [ABSTRACT FROM AUTHOR]

Objectives: The aim was to evaluate the influence of weather parameters on disease activity assessed by Routine Assessment of Patient Index Data (RAPID) scores via a Web-based smartphone application (WebApp). Methods: Correlation of changes of temperature (change of temperature, °C) and air pressure (change of air pressure, hPa) two days prior to and weekly self-assessment of disease activity by RAPID-3 scores over three months. To define background noise and quadrants of weather changes, we defined a central quadrant ± 2 hPa and ± 2° C, called E1. Based on this inner square, four quadrants were defined: A1 = sector left side above with increasing temperature and air pressure (improving weather); B1 = sector right side above; C1 = decreasing temperature and air pressure sector right side down (worsening weather); and D1 = sector left side down. Alterations of RAPID-3 scores analyzed changes in disease activity compared to RAPID-3 scores detected one week in advance. Results: Eighty patients were included in the analysis (median RA duration, 4.5 years; age, 57 years; 59% female). Median disease activity was 2.8 as assessed by DAS 28. In total, 210 time points were analyzed for quadrant A1, 164 for quadrant B1, 160 for quadrant C1, 196 for quadrant D1, and 145 for the inner square E1 were found during follow-up. The middle square E1 was balanced between increasing or decreasing values for RAPID scores. The odds for increasing RAPID scores were 1.33 (95% confidence interval CI: 1.0–1.78) for patients with ameliorating weather conditions which improve or alleviate unfavorable or adverse conditions (A1) compared to 0.98 (CI: 0.67–1.45) for worsening weather (C1) as defined by temperature and air pressure. Conclusions: On average, more patients developed a slight increase of disease activity if they were in the quadrant with increasing temperature and air pressure (improving weather). Thus, no correlation between the worsening of the weather and changing RAPID-3 scores was found. [ABSTRACT FROM AUTHOR]

Even though the streamer process can be identified in nanoseconds and microseconds through experimental measurements, the breakdown time of air discharge is still unknown. The instability of electrons is suspected to be an attachment-instability phenomenon of the channel conductivity. We investigated breakdown time across milliseconds to better understand how the oxygen excitations of the 200–400 nm range influence a high-conductivity channel even with a weaker applied voltage. Experiments were performed with positive impulse voltages ranging from +42 to +75 kV in the step of +6 kV at a 3 cm gap between needle-to-plane electrodes in a horizontal configuration. A spectrometer with an integration time of 70 ms was used to capture the spectra during voltage discharge. The shortest breakdown time was found at +60 kV with 77 ns compared to +66, +72, and +75 kV. We conclude that the shorter breakdown time at +60 kV is primarily due to the oxygen-excited state in O IV at 262.999 nm. This state helps maintain electron flow by preventing electron loss, with a decay time of 2.5 µs, while releasing Joule heat at a temperature of 26,003 K, which optimizes conductivity. This process occurs before the recombination of the O I line at 777.417 nm, which has a significantly shorter decay time of 27 ns. [ABSTRACT FROM AUTHOR]