Concentration Distribution Research Articles

Study on the Vertical Distribution Characteristics of Suspended Sediment Driven by Waves and Currents

Port coasts are affected by waves and tidal currents, and sediment continues to silt up, leading to a reduction in the depth of water in the channel, blocking the channel and seriously affecting the safe operation of ports. The main cause of sediment deposition in ports is suspended sediment transport, and the characteristics of the vertical distribution of suspended sediment concentrations are the embodiment of the suspended sediment transport law. This paper is divided into three parts to study the vertical distribution characteristics of suspended sediment concentrations. Firstly, the shortcomings of the traditional diffusion model were analysed by using the finite mixing theory (FMT); secondly, the sediment mixing length coefficient κs model was introduced and combined with the sediment group settling velocity model to establish the vertical distribution model of suspended sediment concentrations under wave–current; finally, the effects of various factors on the vertical distribution of the suspended sediment concentration were investigated. The results show that the model in this paper has the characteristics of “low variance and low bias”, which solves the problem that κs is difficult to determine. When the model κs < κs′ (κs′ = 0.4), the concentration of suspended sediment predicted by κs′ is overestimated, and vice versa. As the sediment concentration increases, the interaction between particles increases and the vertical distribution of the suspended sediment concentration shows the pattern of “small top and large bottom”. The larger the particle size, the greater the sedimentation rate of the suspended sediment, and a large amount of sediment will be suspended near the bottom without mixing. The higher the wave height, the stronger the boundary layer turbulence and the movement of the water particles’ trajectory, and the smaller the difference in sediment concentration between the bottom and the sea surface.

Experimental investigation of natural gas leakage and dispersion characteristics in utility tunnels under the effects of real facility layout and forced ventilation

Natural gas leakage occurring in underground utility tunnels usually poses a significant threat to public safety. In order to prevent unexpected fires and explosions, the evolution mechanism of natural gas leakage and dispersion in utility tunnels is urgently needed. In this study, an experimental apparatus was built to facilitate the understanding of leakage and dispersion dynamics in utility tunnels. Methane with a purity of 99.9% is used as a surrogate for natural gas. A schlieren imaging system with a Z-shaped optical path was designed to visualize the high-speed gas jet. The concentration distribution, alarm time, dilution efficiency, and gas jet image were analyzed under the effect of various facility layouts, ventilation, and leakage rates. The results show that the gas leakage and dispersion process can be divided into three zones: upwind zone, leak zone, and downwind zone, characterized by complicated airflow collision, high-speed get jets, and stable dilution dispersion respectively. Scenario analysis highlights the significance of key facilities, such as cable brackets, in experimental and numerical modeling due to their impact on dispersion trajectories. Higher ventilation rates prove beneficial in reducing peak concentration, hazardous areas, and enhancing purge efficiency. Conversely, higher leakage rates exacerbate the likelihood and severity of gas explosions. Alarm time exhibits a V-shaped distribution relative to the leak point, while purge time correlates positively with sensor positions. These findings are of practical importance in enhancing quantitative risk assessment and designing mitigation strategies for gas leakage accidents, which helps to improve the safety-risk-control capabilities of utility tunnels.

How ultrasonication treatment drives the interplay between lysinoalanine inhibition and conformational performances: A case study on alkali-extracted rice residue protein isolate.

Lysinoalanine (LAL) formed during alkaline extraction of rice residue protein (RRPI), which limited its application in the food industry. In this study, the influence of ultrasonication parameters (acoustic power density, ultrasound duration, and ultrasound temperature) on the inhibition of LAL formation and conformational attributes of RRPI during alkaline extraction was elucidated. The results suggested that the acoustic power density substantially modified the chemical interaction forces between RRPI molecules. At a power density of 60W/L, the ionic bonds (14.37%) and hydrophobic interactions (49.28%) reached the maximum, while hydrogen bonds (15.29%) and disulfide bonds (21.06%) reached the minimum. Moreover, acoustic power density at 60W/L caused a decrease of 18.02% and 12.2% in α-helix, and β-turn, respectively, shifting toward β-sheet, random coil, with an increase of 7.31% and 36.16%. Following ultrasonication, the protein particle size distribution curve shifted in the direction of smaller particle size, forming a relatively concentrated and uniform protein distribution. Sonication power, temperature, and time decreased the absolute value of Zeta potential. Furthermore, significant destruction in microstructure was elicited by sonication, which made the structure looser and more microparticles. Pearson correlation analysis suggested that the inhibition in the levels of LAL was most influenced by the increase of sulfhydryl groups and Zeta potential, as well as the reduction of α-helix content, in which the alteration of the total sulfhydryl group content had a great impact on the Zeta potential and the free sulfhydryl group. The principal component analysis demonstrated a notable correlation between the total sulfhydryl group and both the Zeta potential and free sulfhydryl group of RRPI.

Research on single-point fast three-dimensional concentration reconstruction of a smoke plume based on the static interference infrared imaging spectroscopy system

To meet the requirements of real-time and effectiveness of three-dimensional concentration telemetry of gas clouds and address the difficulty of fast three-dimensional concentration reconstruction of single instrument smoke plumes, the paper proposes a single-point fast three-dimensional concentration reconstruction of the smoke plume based on a static interference infrared Fourier transform imaging spectrometer (ISIFTS) by using the advantages of high throughput, large field of view, high stability, and rapid detection. Based on the scanning field switching characteristics of ISIFTS, a single instrument quickly scans the dual-field map data to obtain the three-dimensional point cloud of the target scene. Combined with the three-dimensional spatial parameters of the scene, a multi-dimensional re-projection algorithm is constructed based on the Gaussian plume continuous diffusion model to simulate the concentration-path-length product (CL) image, and the measured CL image is solved by analyzing the smoke plume image spectra data. The normalized cross-correlation fitting algorithm is used to perform the optimal matching of simulated-measured CL images, and then the three-dimensional concentration distribution of the plume scene is reconstructed based on the dimension mapping relationship. The field smoke plume telemetry experiment was designed and carried out, and the three-dimensional concentration distribution of plume gas at three emission points in the scene was obtained. The CO2 emission rates were calculated to be 13.572 kg / s, 12.225 kg / s, and 14.114 kg / s, respectively. The data are consistent with the emission rate of the coal-fired thermal power plant, which verifies the effectiveness of the single-point fast three-dimensional concentration reconstruction of the smoke plume method based on the ISIFTS system.

Navigating the Diagnostic Challenges in Lymph Node Cytology: The Case of Reactive Hyperplasia.

Fine needle cytology (FNC) is a pivotal diagnostic tool for distinguishing between benign and malignant lymphadenopathies mainly because of its minimal invasiveness, cost-effectiveness and accuracy. A major requirement for maximising diagnostic accuracy is proper sample management of aspirated cellular material. In this diagnostic process, the morphological evaluation of adequate smears is paramount, guiding cytopathologists in the selection of appropriate ancillary tests through the recognition of cell size and patterns of distribution. Here, we describe a peculiar 'concentric ovals distribution pattern', frequently observed in the FNC of benign reactive lymph nodes, which may represent an aid in the cytological diagnosis of reactive hyperplasia.

Retrieve water quality parameters of urban rivers from hyperspectral images through feature interaction based two-stage method fused with spectral unmixing and spatial relatedness

Monitoring water quality through efficient quantification of water quality parameters (WQPs) is of paramount importance to environmental management of urban rivers. Unmanned aerial vehicle (UAV) remote sensing techniques posed a great opportunity for visualizing spatial distributions of WQPs concentrations with higher flexibility and monitoring frequency compared to satellite remote sensing techniques, assisting to trace potential contamination sources and prevent water quality from degradation. However, current methods of water quality monitoring usually involved large masses of water samples as training data to keep calculation accuracy every time their study area changed, increasing financial cost and incurring time delay in monitoring and evaluating water quality. This study proposed a UAV-based two-stage multidirectional fusion with probabilistic matrix factorization (TSMF-PMF) method in unified framework, to effectively quantify WQPs including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and turbidity from UAV hyperspectral images. TSMF-PMF established feature interaction and outlier feedback module, ensuring relatively high calculation stability with less training samples. The experimental results showed that TSMF-PMF achieved good performance on predicting concentrations of WQPs with coefficient of determination (R2) and mean absolute percentage error (MAPE) ranging from 0.82 to 0.91 and from 5.35 % to 10.23 %. This study established theoretical and technical foundation to optimize environmental management scheme of urban rivers and provided an application demonstration.

Quantum efficiency enhancement of reflective GaAs photocathodes with exponential-doping structure generating a favorable built-in electric field

The rapid development of GaAs photocathodes has led to an increased focus on the attainment of high quantum efficiency. Three types of exponential-doping structures with a high to low doping concentration distribution from the interior to the surface are proposed for reflective GaAs emission layers. These three structures generate different built-in electric fields that facilitate photoelectron emission. The one-dimensional continuity equations for the increasing, constant, and decreasing types of built-in electric fields are derived, respectively. The electron concentration distribution and quantum efficiency varying with the wavelength are solved numerically by the finite difference method. The simulation results indicate that the quantum efficiency of the GaAs photocathode with the increasing type of built-in electric field is superior to that with the constant built-in electric field, while the GaAs photocathode with the decreasing type of built-in electric field shows the worst performance. Then, the designed GaAs photocathodes with the increasing and constant types of built-in electric fields are grown by metal-organic chemical vapor deposition and activated by cesium-oxygen alternating deposition. The measured spectral response curves show that the quantum efficiency of the GaAs photocathode with the increasing type of built-in electric field is higher in the whole band than that with the constant type of built-in electric field. In addition, the exponential-doping structure generating the increasing type of built-in electric field is beneficial for improving the surface potential barrier and increasing the surface electron escape probability.

Incorporating meander to account for the impact of low winds in area source modeling; AERMOD as a case study

ABSTRACT A variety of sources of pollutant emissions can be represented as area sources. These include manure lagoons, landfills, wastewater treatment ponds, and highways. A group of point sources can also be treated as an area source. The impact of an area source is usually computed by representing the area source as a set of line sources perpendicular to the wind direction. As for point sources, the Gaussian horizontal concentration distribution used to compute the contributions of the line sources is likely to overestimate ground-level concentrations when the wind speed is comparable to the standard deviation of the horizontal velocity fluctuations. A variety of methods are used to mitigate this overestimation under these conditions, referred to as meander. As an example of one these approaches, we examine that of AERMOD, EPA’s regulatory model. AERMOD includes meander in modeling the impact of point and volume sources, but has not yet incorporated it into AERMOD’s area source algorithm. This paper describes an approach to include meander in AERMOD’s area source algorithm and demonstrates its impact on concentrations associated with area sources. Implications: Inclusion of wind direction meander in modeling dispersion when the wind speed is low is important in ensuring that AERMOD does not overestimate concentrations under these conditions. In view of the importance of area sources of pollution, the results presented in this paper represent a potential enhancement of AERMOD’s ability to estimate the upper end of the concentration distribution, which forms the basis of the regulatory acceptance of the model.

Quantification of contaminant mass discharge and uncertainties: Method and challenges in application at contaminated sites

Contaminant mass discharge (CMD) estimation involves combining multilevel concentration and flow measurements to quantify the contaminant mass passing through a control plane downgradient of a point source. However, geological heterogeneities and limited data introduce uncertainties that complicate CMD estimation and risk assessment. Although CMD is increasingly used in groundwater management, methods for quantifying and handling these uncertainties are still needed. This study develops and tests a CMD estimation method based on Bayesian geostatistics to quantify CMD uncertainties using data from a control plane perpendicular to the contaminant plume.By combining geostatistical conditional simulations of the spatial concentration distribution with the flow, an ensemble of CMD realizations is generated, from which a cumulative distribution function is derived. A key element of this approach is the use of a macrodispersive transport model to simulate the spatial concentration trend. This ensures that the estimated concentration reflects the expected physical behavior of the contaminant plume while also allowing the integration of site-specific conceptual information.The method is applicable to plumes with dissolved contaminants, such as chlorinated solvents, petroleum hydrocarbons, Per- and polyfluoroalkyl substances (PFAS) and pesticides. Site-specific conceptual understanding is used to inform the prior probability density functions of the structural model parameters and to define acceptable simulated concentration limits. We applied the method at three sites contaminated with chlorinated ethenes, demonstrating its robustness across varying information levels and data availability.Our results shows that strong site-specific conceptual knowledge and high sampling density constrain the CMD uncertainty (CV = 21 %) and results in estimated model parameters and a spatial concentration distribution that agrees well with the conceptual model. For a site with less data and limited conceptual knowledge, CMD and concentration distribution estimates are still feasible, though with higher uncertainty (CV = 41 %). Extending the method to account for multiple source zones and complex plume migration improved parameter identification and reduced the 95 % CMD confidence interval by 11 % ([4950–8750] to [5090–8480] g yr−1), while also providing a spatial concentration distribution in better agreement with the plume conceptualization.This study highlights the importance of integrating site-specific conceptual knowledge in CMD estimation, particularly for less-sampled sites. The method can furthermore assist in identifying remediation targets, evaluating remedial effectiveness, and optimizing sampling strategies.

The influence of pulsation ventilation on the removal and distribution of gas accumulation areas during gas leakage in industrial plants

A ventilation system with a constant velocity air supply might form airflow stagnant zones in industrial plants, making it challenging to dilute hazardous gas effectively. In this study, a novel ventilation mode called pulsating ventilation, which can potentially dilute the hazardous gas better, was applied in a ventilated room with nozzle air supply. Three different scenarios of gas accumulation were assumed, with the location of gas accumulation situated at the rear, near the floor, and in the corners of the room. Both the distribution of CO2 concentration and the efficiency of reducing the indoor CO2 concentration to the safety threshold were analyzed to evaluate the ventilation performance of pulsating ventilation. The results showed that pulsating ventilation outperformed constant velocity air supply in expeditiously eradicating gas accumulation areas for equivalent total air volumes. When the gas accumulation areas were located at the rear of the room, close to the floor, and in the corner of the room, pulsation ventilation reduced the time for the indoor CO2 concentration to drop to the safety threshold by 36.19%, 27.23%, and 36.25%, respectively. Holding the period constant, an increased amplitude correlated with a swifter decrease in peak pollutant concentration. Except for the case where the gas accumulation areas are close to the floor, when the amplitude is constant, the larger the period, the faster the peak concentration in the gas accumulation areas decreases.

Numerical investigation of PEMFC performance enhancement through combined design of anodic fishbone ridge groove channel and optimal gas diffusion layer porosity gradient

The flow field plate is one of the core components of proton exchange membrane fuel cells (PEMFC), and its structure significantly influences the thermo-electrochemical coupling transport characteristics of PEMFCs. Optimizing the parameters of the flow channels of bipolar plates is crucial for enhancing the mass transfer of reacting gas and improving water removal capacity. In this study, an anodal fishbone ridge groove combined flow channel (F-SFC) is designed to enhance the diffusion uniformity of anode hydrogen gas, and a 3D multi-phase model of PEMFC is established using the multiphysics simulation software COMSOL Multiphysics. The F-SFC was compared with traditional bipolar plates featuring symmetric anode and cathode flow channels in terms of overall output performance, and the results are presented. The findings indicate that the F-SFC design achieves an average increase of 28.78% in current density and 21.07% in power density compared to conventional fishbone flow channels. When compared to traditional serpentine flow channels, the F-SFC design shows a 13.5% increase in current density and a 10.42% increase in power density. Furthermore, adding multilayer porosity gradients to gas diffusion layers (GDLs) greatly improves internal mass transfer. A gradient porosity of 0.7, 0.5, and 0.3 along the Z-axis produces a more equal distribution of current density and water concentration on the membrane. This work sheds fresh light on optimizing PEMFC design for increased power density, providing useful theoretical advice for future advances.

The enhanced heat transfer and flow dynamics of tangent hyperbolic and Newtonian nanofluids under inclined variable magnetic field

This paper aims to analyze the thermal conductivity of tangent hyperbolic non-Newtonian fluids and Newtonian nanofluids over a porous, inclined, stretching sheet with motile microorganisms. It also examines the impact of inclined variable magnetic field, activation energy, thermal radiation, thermophoresis and Brownian motion. The novelty of this research lies in the simultaneous use of inclined geometry and an inclined variable magnetic field. The findings optimize environmental and food processing applications, drug delivery, thermal management, lubrication, and enhanced oil recovery. A far-reaching analysis compares the behaviors of tangent hyperbolic fluid with Newtonian fluid. Appropriate similarity functions are used to convert the governing system of nonlinear PDEs for tangent hyperbolic fluid to dimensionless ODE. MATLAB’s boundary value solver BVP4C is then used to solve these ODEs numerically. This study explores various characteristics, including temperature, velocity, concentration, and microorganism distribution. In the essence of this computational study, the impacts of inclined angle, porosity, mixed convection, Hartmann number and Weissenberg number on the velocity of the fluid are analyzed. The main findings are that higher Prandtl numbers reduce heat transfer rates, while thermophoresis and Brownian motion enhance heat flow. Lewis and Peclet numbers show declining tendencies in motile microorganisms, with magnetic fields influencing their distribution within the fluid; this is useful in biotechnology and environmental applications. Consequently, the effect is greater in the case of non-Newtonian fluids which depend more on the inclination angle, inclined variable magnetic field strength, thermal conductivity and activation energy when compared with the Newtonian fluids.

Preparation of porous Si3N4 ceramics with excellent mechanical properties:effect of the grain growth mechanism on microstructure evolution

In recent years, porous Si3N4 ceramics have been recognized as the most promising materials for radomes. In this study, porous Si3N4 ceramics with excellent mechanical properties have been successfully prepared by adding 2 wt% Lu2O3, of which the effect of sintering temperature on the grain growth mechanism is investigated for microstructure tailoring. When sintered at 1720°C, the lower liquid viscosity allows the grain growth rate to match with dissolution-precipitation process. Through this process, the grains further grew together to form a more homogeneous rod-like structure, resulting in a more concentrated aspect ratio and particle size distribution. In addition, the grains along the c-axis grew faster due to the Lu3+ ions, resulting in a higher aspect ratio. However, when further increased to 1750°C, the viscosity of the liquid decreases significantly, leading to the precipitation of a large number of β-Si3N4 nuclei. Due to the combined effect of the steric hindrance and the liquid phase mainly distributed at the ends of the grains, a short and thick morphology with a thick center and fine ends is formed, which is unfavorable to the bending strength. Therefore, when the porosity of the sample at 1720°C is 64.5%, the bending strength can still reach 162 MPa with a structure factor of 2.82.

Evolution of Microstructure and Hardness during Carburization Heat Treatment of Heavy-duty Gear Steels: Numerical Prediction and Experimental Study

Abstract In order to solve the problems of long process cycle, low efficiency and high cost in the carburization heat treatment process of 18Cr2Ni4WA heavy-duty gear steel. The carbon concentration distribution of 18Cr2Ni4WA steel under conventional carburizing process at 930℃ was studied by combining numerical simulation with experimental research. The results show that the carbon concentration distribution predicted by the simulation is in good agreement with the experimental results. The microstructure of the surface layer after low-temperature tempering consists mainly of fine acicular tempered martensite, while the core consists mainly of lath tempered martensite and bainite. The increase in hardness after carburization is mainly attributed to the solid solution strengthening of the carbon atoms. The increase in hardness after cryogenic treatment is mainly attributed to the precipitation strengthening of the carbides. In addition, compared to the conventional carburization at 930°C, the high temperature carburizations at 950°C and 970°C reduced the carburization time by 37.2% and 53.5%, respectively.

Experimental and molecular dynamics simulation studies on the effect of composite surfactants on the wettability of anthracite coal

In order to improve the wettability of coal bed water injection, the effects of several composite surfactants on the wettability of anthracite coal were investigated. Firstly, the wettability of different composite surfactants on anthracite was analysed by macroscopic experiments (surface tension and settling time) to determine the optimal concentration and optimal ratio of composite surfactants. Secondly, the effects of adsorption of different composite surfactants on the physicochemical properties of the coal dust surface were investigated by mesoscopic experiments (scanning electron microscopy, energy spectrometer analysis, infrared spectroscopy, X-ray electron spectroscopy and zeta potential), and the results showed that the content of hydrophilic functional groups (Si-O-Si, C-O-C, C-O and C=O) on the surface of anthracite coal after treatment with the composite surfactant increased significantly, and the surface potential value decreased significantly in absolute value, agglomerated large coal particles would be formed on the coal surface, and the cracks between coal particles were favourable for the penetration of aqueous solution. Finally, the synergistic mechanism of different composite surfactants was analysed from the perspective of microscopic molecular simulation. The results showed that the composite surfactants enhanced the interaction energy of the coal/composite surfactant/water system, improved the relative concentration distribution of the system, and increased the diffusion coefficient of water molecules. The results of the study can provide valuable guidance for the development of new composite surfactants with wetting effect, which has important application value for mine dust control.

Vertical concentration distribution of fine settling particles in a pulsatile laminar open channel flow

Vertical concentration distribution of fine settling particles in a pulsatile laminar open channel flow

Study on concentration distribution and detonation characteristics of typical multiphase fuel in orthogonal flow field

The fuel concentration distribution and detonation characteristics are important for performance evaluation. In order to meet the needs of airdrop, launcher and missile, the transient flow and detonation process of multiphase fuel in orthogonal flow field are analyzed by experiments and numerical simulations. The dynamic detonation model of ethyl ether (EE), propylene oxide (PO) and tetrahydro dicyclopentadiene (JP-10) is built. The flow process, concentration distribution, overpressure, temperature and detonation wave structure of the three fuels are obtained. The results show that the falling velocity has obvious influence on the detonation process of fuel droplets. The falling velocity of 0.5 Ma makes the fuel concentration distribution more uniform and the energy output is better. The peak overpressure of EE, PO and JP-10 is 2.88 MPa, 3.21 MPa and 2.96 MPa respectively. The peak temperature is 2885 K, 3230 K and 2955 K respectively. The burn out rate increases by 8.5%, 8.1% and 13.7% respectively. JP-10 has higher sensitivity to falling velocity, and there are obvious secondary peaks of overpressure in low-speed state. PO has higher stability for falling velocity, and the scaled length of high temperature/pressure after detonation wave is 0.145 m·kg-1/3.

ECOLOGICAL NICHES AND IMPLICATIONS FOR REFORESTATION OF PTEROCARPUS ERINACEUS, KHAYA SENEGALENSIS AND ISOBERLINIA DOKA IN THE CLASSIFIED FORESTS OF NORTHERN COTE DIVOIRE

Deforestation in Cote dIvoire, particularly in the Pale and Pouniakele classified forests, threatens biodiversity and essential ecosystem services. This study explores the potential of Pterocarpus erinaceus, Khaya senegalensis, and Isoberliniadoka to restore degraded ecosystems through reforestation projects, using maximum entropy modeling. The objective is to analyze the ecological niches of these species in order to optimize reforestation strategies. The results show that Pterocarpus erinaceus has a high tolerance to climate variations, with an average AUC of 0.878, and a concentrated distribution in the central and northern savannahs. The main factors influencing its presence are the standard deviation of temperatures (47%) and humidity (15.4%). Khaya senegalensis, on the other hand, is well adapted to open environments with low vegetation cover and high climate variability. Its mean AUC of 0.893 indicates a robust prediction, with areas of presence in the central-eastern part of the country. Major contributions include temperature standard deviation (21.4%) and NDVI (18.5%). Finally, Isoberliniadoka shows greater sensitivity to stable climatic conditions, with a mean AUC of 0.848 and a presence limited to northern regions, where forest cover (32.1%) and mean temperature (39.7%) are the dominant variables. Ecological differences are observed between species, mainly influenced by climate variability and vegetation density. This implies the importance of adapting reforestation programs to the environmental specificities of each species. This study offers practical recommendations to improve the sustainability of reforestation projects in Cote dIvoire, taking into account local ecological challenges.

Distribution of Air pollutant Concentration and Ammonium conversion rate in Livestock Areas: Focusing on Boryeong

Objectives:The association between the generation of fine particulate matter (PM2.5) and ammonia is well-established, highlighting the importance of managing ammonia as a primary means to reduce particulate matter. However, domestic research on ammonia emissions, particularly in livestock areas, which are major sources of ammonia, is insufficient. This study aims to contribute to pollutant management on a national scale by conducting air pollutant measurements and analyses in livestock areas. Methods:Real-time analysis and monitoring of air and weather conditions were carried out in Boryeong, Chungcheongnam-do, from 2021 to 2022. Statistical analysis was then employed to investigate the correlation between observed air pollutants (ammonia, nitrogen oxides, sulfur oxides, ozone and particle matters) and PM2.5. Results and Discussion:As a result of the analysis, the concentration of air pollutants in Boryeong showed a seasonal tendancy to decrease in summer and increase after that. Most substances such as NO2, SO2, and PM10 were observed within the standard values. In the case of ammonia, domestic air environment standards are not in place, but the annual average was found to be 61.5 ± 55.3 ppb, higher than in other research results. This discrepancy is attributed to the influence of nearby livestock houses. It was also observed that PM2.5 exceeded the annual standard value of 15 μg/m3 in spring (30.1 μg/m3), summer (18.3 μg/m3), autumn (25.3 μg/m3) and winter (31.7 μg/m3), respectively. During this period, ammonium (NH4+, 32.8%), nitrate (NO3-, 35.9%), and sulfate (SO42-, 19.7%) comprised the majority of particulate pollutants in PM2.5. The ammonia-ammonium conversion rate (NHR) was 0.08 annual average, and it was found that gas/ion phase changes were affected by seasonal weather conditions (temperature and relative humidity). As a result of analyzing the NHR according to the PM2.5 concentration, it was found that the higher the PM2.5 concentration, the higher the NHR. Furthermore, although the measurement area of this study exhibited high ammonia concentration, the NHR was low. This suggests that the contribution rate of ammonia to PM2.5 was relatively low compared to the other studies.Conclusion:As a result, there is a need for measures to reduce the high concentrations of ammonia in livestock areas. Simultaneously, considering the diverse mechanisms involved in particulate matter formation, it is suggested that management of pollutants such as nitrogen oxides, sulfur oxides including ammonia should be implemented.

Numerical Study of Detonation Waves in Gas Suspensions with Spatially Inhomogeneous Particle Concentration Distribution in Sharply Expanding Pipes

The article presents some results of a numerical study of detonation waves in gas suspensions with a spatially inhomogeneous distribution of particle concentration in sharply expanding pipes obtained by the large particle method. The purpose of the research is to study the influence of pipeline geometry and longitudinally spatially inhomogeneous distribution of particle concentration on the propagation of detonation waves in gas suspensions. It is shown that the size of the narrow and wide parts of the pipeline, as well as, the spatially inhomogeneous distribution of particle concentrations, qualitatively and quantitatively affect this process. Three detonation modes have been identified: continuous wave propagation, complete cessation, and partial disruption with subsequent recovery. It has been established that, at a fixed total mass of suspension, a layer with a linearly decreasing law of change in the concentration of unitary fuel particles better attenuates detonation waves than with a linearly increasing and homogeneous one.