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The present study examined the influence of controlled heat injection on the sedimentation of fine particles in a trapezoidal container, aiming to explore the combined effects of the Boycott effect and convection induced by heating. The experimental design incorporates varying initial particle concentrations (1500 ppm and 3000 ppm) and heat injection levels (0 W, 4.5 W, and 9 W imposed power) to analyze sedimentation dynamics, focusing on concentration distribution patterns and clear water production. The findings reveal complex interactions between heat injection and particle concentration. At 1500 ppm, heat injection shows minimal impact on sedimentation due to particle resuspension. However, at 3000 ppm, particularly with a 9 W heat injection, the sedimentation performance improves significantly during the early stages of the process, achieving an average sedimentation rate approximately 40 % higher than without heat injection and an average clear water generation rate nearly four times greater. These clear water generation rates were determined considering water with particle concentrations below 20 % of the initial concentration (300 ppm for 1500 ppm and 600 ppm for 3000 ppm). A further analysis of the column and row data reveals stratification patterns influenced by heat injection, characterized by distinct horizontal and vertical layers. Additionally, the results suggest that wall temperature distributions are largely unaffected by the initial particle concentration, while clear water production and sedimentation efficiency are highly dependent on heat levels and initial particle density. These results highlight the potential of heat-enhanced sedimentation to improve separation processes in industrial systems. Specifically, they provide valuable insights for optimizing the design and efficiency of lamella settlers, commonly used in water treatment and other particulate separation applications. Future studies will explore the combined use of coagulants and flocculants and the application of these findings to real mixtures, such as mine water or wastewater, to further validate and expand their industrial applicability. [ABSTRACT FROM AUTHOR]

A large amount of pollutants are generated during tunnel blasting construction, which seriously endangers the life and health of construction personnel. Reasonable design and resolution of ventilation issues have become the key to ensure the safety of engineering construction. This study established a ventilation simulation engineering during tunnel construction using numerical methods of computational fluid dynamics. The mechanism of the turbulent air flow generated by the restriction of air jet and wall is proved by simulating the distribution of the flow field in the tunnel under various ventilation modes. The retarding effect of vortex conducted by air flow and pollutant transport diffusion mechanism resulted in two peak distributions of pollutants. The discharge of harmful gases has both the transport effect of the main airflow and the diffusion effect of the turbulent airflow. Jet fans can effectively accelerate the dispersion of pollutants in the vortex zone. The time cost law of ventilation saving under different ventilation modes is found through comparison. On this basis, a new annular ventilation method combining longitudinal and transverse ventilation in tunnels is proposed. Not only can it greatly save ventilation time and costs, but it also provides a very friendly solution to the residual pollutants in the vicinity of the working face. The research work of this project provides important reference and guidance value for practical engineering. Highlights: The distribution law of air flow field and the mechanism of pollutant transport and diffusion in the tunnel are revealed. A new type of ventilation mode is constructed based on numerical simulation. The advantages and disadvantages of different ventilation modes are analyzed and compared to provide guidance for practical projects. [ABSTRACT FROM AUTHOR]

The blast furnace smelting of vanadium–titanium ore plays a crucial role in the efficient utilization of vanadium-titanium resources. In this research, a detailed numerical simulation study of the temperature, velocity, and concentration fields during the smelting process in a vanadium–titanium blast furnace was conducted. The actual production data from a 1750 m3 vanadium–titanium blast furnace was utilized, combined with softening and dripping parameters and material balance calculations, to develop a two-dimensional blast furnace model. This model was employed to analyze the effects of varying smelting intensities on the internal operating conditions of the furnace. The study found that as smelting intensity increased, significant changes occurred in the temperature fields and CO concentration fields within the furnace, thereby affecting the reduction efficiency of the burdens. Additionally, this research also shows that increasing the proportion of Baima pellets in the furnace will lead to the expansion of the soft melting zone and the upward movement of the soft melting zone. This investigation not only revealed the variations in the internal physical fields of the blast furnace under different operating conditions but also provided theoretical foundations and references for optimizing the design and operation of vanadium–titanium blast furnaces. By comparing the velocity field under different smelting intensities, it was found that the difference was small, which was mainly related to the expansion behavior of the pellets. These findings provide an important scientific basis for further improving the efficiency of blast furnace smelting and reducing costs. [ABSTRACT FROM AUTHOR]

The characteristics of flow field and the brine distribution will greatly affect the cavern expansion and final cavern shape in the process of constructing salt cavern gas storage, while the flow characteristics and concentration distribution can’t be monitored by technical means. To study flow characteristics, brine concentration distribution and their impact on cavern shape expansion during the multi-step salt cavern construction, numerical simulation calculations were conducted based on the established multi-physics coupled flow model, and the results were compared with field data of two storage wells in Jintan. The simulation results were consistent with the field data, which verified the accuracy of the model. Based on the simulation results and data, the flow field characteristics and brine concentration distribution in each stage of solution mining were analyzed, and how flow characteristics and brine concentration distribution affect the cavern expansion was analyzed. The results show that there will form a vortex in cavern during positive circulation, which mainly cause erosion and inhibits dissolution during solution mining. There will form two vortices in cavern during reverse circulation. The one in lower part promoting the discharge of brine and the another one in upper part promoting dissolution Forced convection will cause vortex, and the strength of vortex will gradually decrease with the expansion of the cavern. The vortex makes the fluid flow in the cavern, and promotes the process of convection diffusion, thus affecting the distribution of brine concentration, and ultimately affecting the expansion of the cavern. The shape expansion of the cavern can be controlled by adjusting the positive and negative circulation mode, the position of the tube, the position of the oil cushion, and the injection rate. In the early stages of cavern construction, erosion plays a dominant role, which resulting in high cavern construction efficiency, resulting in a slower cavity making rate because of the small surface area of the cavern. The cavern mainly extends towards the middle and lower parts. In the later stages, as the cavity expands, the main effect is dissolution, and the rate of cavern construction is high. The cavity mainly expands towards the middle and upper parts. The research results and rules provide a certain theoretical basis for cavern construction design in field, and have guiding significance for improving construction efficiency and optimizing parameters. [ABSTRACT FROM AUTHOR]

The present study examined the influence of controlled heat injection on the sedimentation of fine particles in a trapezoidal container, aiming to explore the combined effects of the Boycott effect and convection induced by heating. The experimental design incorporates varying initial particle concentrations (1500 ppm and 3000 ppm) and heat injection levels (0 W, 4.5 W, and 9 W imposed power) to analyze sedimentation dynamics, focusing on concentration distribution patterns and clear water production. The findings reveal complex interactions between heat injection and particle concentration. At 1500 ppm, heat injection shows minimal impact on sedimentation due to particle resuspension. However, at 3000 ppm, particularly with a 9 W heat injection, the sedimentation performance improves significantly during the early stages of the process, achieving an average sedimentation rate approximately 40 % higher than without heat injection and an average clear water generation rate nearly four times greater. These clear water generation rates were determined considering water with particle concentrations below 20 % of the initial concentration (300 ppm for 1500 ppm and 600 ppm for 3000 ppm). A further analysis of the column and row data reveals stratification patterns influenced by heat injection, characterized by distinct horizontal and vertical layers. Additionally, the results suggest that wall temperature distributions are largely unaffected by the initial particle concentration, while clear water production and sedimentation efficiency are highly dependent on heat levels and initial particle density. These results highlight the potential of heat-enhanced sedimentation to improve separation processes in industrial systems. Specifically, they provide valuable insights for optimizing the design and efficiency of lamella settlers, commonly used in water treatment and other particulate separation applications. Future studies will explore the combined use of coagulants and flocculants and the application of these findings to real mixtures, such as mine water or wastewater, to further validate and expand their industrial applicability.

Acoustic tomography utilizes sensor arrays to collect sound wave signals, enabling non-contact measurement of physical parameters within an area of interest. Compared to optical technologies, acoustic tomography offers the advantages of low cost, low maintenance, and easy installation. Current research in acoustic tomography mainly focuses on reconstruction algorithms for temperature fields, while monitoring the composition and concentration of gases is significant for ensuring safety and improving efficiency, such as in scenarios like boiler furnaces and aviation engine nozzles. In excitable gases, the speed of sound exhibits an S-shaped curve that changes with frequency, a characteristic that could be potentially useful for acoustic tomography. Therefore, this study primarily discusses the quantitative calculation of gas concentration and temperature based on the dispersion of the speed of sound. By employing graphic processing and pattern matching methods, a coupled relationship of the dispersion of the speed of sound with gas concentration and temperature is established. The projection intersection method is used to calculate the concentration and temperature of binary and ternary gas mixtures. Combined with the inversion method, a joint reconstruction method for gas concentration fields and temperature fields based on the dispersion of the speed of sound is developed. The feasibility of the proposed simultaneous reconstruction method for temperature and concentration fields is validated using numerical simulations. Additionally, an acoustic tomography experimental system was set up to conduct reconstruction experiments for binary gas concentration fields and temperature fields, confirming the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In order to solve the problem of spontaneous combustion of coal in U-shaped stope during dynamic advance, a multiphysical field coupled mathematical model including the inlet and return airway, working face and goaf is established, and the reasonableness of the model is verified by field measurement data. The simulation analyzed the law of temperature field and oxygen concentration field in the goaf with the dynamic advance of working face, and further studied the influence of surrounding rock temperature, air flow temperature and working face advance speed on the self-heating of coal oxidation in the mining area. The results indicate that the temperature field on the inlet side of the goaf forms the phenomenon of high temperature region tailing in the shape of “wing section” in the process of advancing the working face, and the temperature of the high-temperature area gradually decreases under the effect of compaction of the goaf and heat dissipation of the surrounding rock; the temperature in the goaf continues to rise after the stoppage of mining, but the high-temperature area migrates to the working face; in the early stage of mining, different ventilation temperature has almost no effect on the maximum temperature in the mining area, while in the later stage of mining, the higher the ventilation temperature, the higher the maximum temperature in the mining area; the faster the working face advances, the lower the maximum temperature in the mining area.

Currently, the sampling problem has gained wide popularity in the field of autonomous mobile agent control due to the wide range of practical and fundamental problems described with its framework. This paper considers a combined decentralized control strategy that incorporates both elements of biologically inspired and gradient-based approaches. Its key feature is multitasking, consisting in the possibility of solving several tasks in parallel included in the sampling problem: localization and monitoring of several sources and restoration of the given level line boundaries. [ABSTRACT FROM AUTHOR]

Many high-performance fluid dynamic models do not consider fluids in a rotating environment and often require a significant amount of computational time. The current study proposes a novel parameter-based field reconstruction convolutional neural network (PFR-CNN) approach to model the solute concentration field in rotationally influenced fluids. A new three-dimensional (3D) numerical solver, TwoLiquidMixingCoriolisFoam, was implemented within the framework of OpenFOAM to simulate effluents subjected to the influence of rotation. Subsequently, the developed numerical solver was employed to conduct numerical experiments to generate numerical data. A PFR-CNN was designed to predict the concentration fields of neutrally buoyant effluents in rotating water bodies based on the Froude number (Fr) and Rossby number (Ro). The proposed PFR-CNN was trained and validated with a train-validation dataset. The predicted concentration fields for two additional tests demonstrated the good performance of the proposed approach, and the algorithm performed better than traditional approaches. This study offers a new 3D numerical solver, and a novel PFR-CNN approach can predict solute transport subjected to the effects of rotation in few seconds, and the PFR-CNN can significantly reduce the computational costs. The study can significantly advance the ability to model flow and solute transport processes, and the proposed CNN-based approach can potentially be employed to predict the spatial distribution of any physical variable in the lentic, ocean, and earth system. [ABSTRACT FROM AUTHOR]

• The forward simulation of gas leakage concentration field in open station yard is carried out. • The optimal layout of leakage monitoring of multiple laser detectors is proposed. • A gas leakage inversion location method under multi-path concentration monitoring is proposed. • The accuracy and reliability of the model are verified by single-point and two-point leakage experiments. Natural gas leakage can easily lead to safety accidents and environmental pollution, affecting normal safe production and sustainable energy development. Among them, the leakage accident caused by the integrity failure of the process equipment is particularly noteworthy. To improve the efficiency of methane leakage monitoring and the accuracy of leakage source location, the forward prediction model of leakage concentration field, the optimization model of monitoring equipment layout, and the inversion model of leakage source location were established. To evaluate the model's applicability, an open-air oil–gas joint station was selected for experimental simulation. The monitoring data of the open circuit laser methane sensor and the forward simulation results of the leakage concentration field were compared. It was found that at 30 % methane concentration, the monitoring distance was 0–6 m, with high monitoring accuracy. Then, by eliminating redundant monitoring sensors, three leakage field concentration monitoring paths are formed. A representative leakage source scenario set is selected for inversion localization. In the simulation of the single-point leakage experiment, the leakage location error is 1.824 m, and the average relative error is 3.6 %. Through error analysis, the results show that the inversion positioning model can also have a good adaptability to the parameter estimation of the leakage source when there are only 3 sets of observation data. [ABSTRACT FROM AUTHOR]

Currently, the sampling problem has gained wide popularity in the field of autonomous mobile agent control due to the wide range of practical and fundamental problems described with its framework. This paper considers a combined decentralized control strategy that incorporates both elements of biologically inspired and gradient-based approaches. Its key feature is multitasking, consisting in the possibility of solving several tasks in parallel included in the sampling problem: localization and monitoring of several sources and restoration of the given level line boundaries.

In order to solve the problem of the uneven distribution of the flow and ammonia concentration field in the selective catalytic reduction (SCR) denitrification system of a 660 MW coal-fired power plant, a three-dimensional computational fluid dynamics (CFD) model was established at a scale of 1:1. The existing flow guide and ammonia fume mixing device were then calibrated and optimized. The relative standard deviation of the velocity field distribution upstream of the ammonia injection grid (AIG) was optimized from 15.4% to 9.9%, with a reasonable radius of the deflector at the inlet flue elbows, and the relative standard deviation of the velocity field distribution above the inlet surface of the first catalyst layer in the reactor was optimized from 25.4% to 10.2% by adjusting the angle between the deflector and the wall plate of the inlet hood. Additionally, with the use of a double-layer spoiler ammonia fume mixing device, the relative standard deviation of the ammonia mass concentration distribution above the inlet surface of the first catalyst layer in the reactor was optimized from 12.9% to 5.3%. This paper can provide a valuable reference with practical implications for subsequent research. [ABSTRACT FROM AUTHOR]

In order to solve the poor flow performance issues of selective catalytic reduction (SCR) denitration systems, the effect of the static mixer on the flow field was studied using computational fluid dynamics (CFD) numerical simulations. Based on the analysis of the original SCR denitration system, two static mixers were selected to explore their influence on system performance. The results show that both static mixers can effectively improve the denitration performance under different conditions. The static mixer with a rotating arrangement showed a better performance in the uniformity of concentration. The pressure loss without a static mixer is 834 Pa, and the pressure loss increases by 94 Pa and 73 Pa for rotating and X-arranged static mixers, respectively. Meanwhile, a static mixer will increase energy loss. Therefore, power plants can choose the layout of their static mixers according to the actual situation to achieve the optimal performance. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) is a kind of clean energy, and many LNG-powered vessels have been designed and built around the world. However, LNG introduces the potential risk of leakage and explosion accidents; thus, it is necessary to conduct safety assessments on the layout of typical facilities during the initial design stage. In this paper, an on-deck LNG fuel area model is established by employing the computational fluid dynamics (CFD) method according to an LNG-powered Aframax oil tanker. The distribution of potential dangerous areas on the concentration field and temperature field is presented under leakage and diffusion accident conditions with vent masts of different heights. The results show the following: the gas concentration rises rapidly at the initial stage of leakage and tends to stabilize after a certain period; the leakage and diffusion trend of light gas is basically the same as that of heavy gas, and the lowest heavy gas and light gas temperature on the deck between the storage tank and the upper building is -7.9 C and 4.7 °C, respectively, when the venting mast leakage point is at the height of 6 m; and the higher the mast leakage point is, the more safe the ship design. For safety considerations, the height of the venting mast designed in this paper should not be lower than the height of the LNG storage tank, which is 10 m.

The flue gas temperature of the Smelting Reduction Vessel (SRV) in the HIsmelt process is high while the temperature of the molten iron is low. Therefore, the heat transfer efficiency between the upper and lower regions in the SRV needs to be further improved. The fluid flow and heat transfer characteristics inside the SRV were studied to derive the mass fraction, temperature distribution, and gas motion. The error between the simulated and measured values remained stable within 5%. The gas in the centre of the SRV shows a high-speed vortex flow. The combustion reaction mainly occurs in the centre of the furnace. Since the heat transfer in the furnace is mainly influenced by the gas flow, the high-temperature zone shows a U-shaped distribution and is mainly around the centre of the region, the oxygen lance outlet, and the furnace wall. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The spatial distribution of elements can be regarded as a numerical field of concentration values with a continuous spatial coverage. An active area of research is to discover geologically meaningful relationships among elements from their spatial distribution. To solve this problem, we proposed an association rule mining method based on clustered events of spatial autocorrelation and applied it to the polymetallic deposits of the Chahanwusu River area, Qinghai Province, China. The elemental data for stream sediments were first clustered into HH (high–high), LL (low–low), HL (high–low), and LH (low–high) groups by using local Moran's I clustering map (LMIC). Then, the Apriori algorithm was used to mine the association rules among different elements in these clusters. More than 86% of the mined rule points are located within 1000 m of faults and near known ore occurrences and occur in the upper reaches of the stream and catchment areas. In addition, we found that the Middle Triassic granodiorite is enriched in sulfophile elements, e.g., Zn, Ag, and Cd, and the Early Permian granite quartz diorite (P1γδο) coexists with Cu and associated elements. Therefore, the proposed algorithm is an effective method for mining coexistence patterns of elements and provides an insight into their enrichment mechanisms. [ABSTRACT FROM AUTHOR]

Ensuring adequate ventilation during tunnel construction is a critical issue that directly affects construction efficiency. A good ventilation environment can effectively guarantee the construction progress. In this paper, by repeatedly selecting the flow field simulation parameters and continuously summarizing the calculation methods, a reasonable model is selected to simulate the tunnel engineering. Specifically, the eddy current zone near the working face is obtained by analysing the flow field of forced ventilation tunnels. Furthermore, we analyse the dispersion and accumulation of harmful gases in the tunnel. The CO concentration at typical locations in the tunnel is also examined in order to determine areas with the lowest likelihood of harmful gas discharge. We then propose adding a jet fan to the tunnel to create an extraction plus ventilation tunnel. Simulation results reveal that the addition of a jet fan causes eddy currents that improve the extraction of harmful gases, thereby greatly reducing ventilation time and increasing efficiency. The results of the model can effectively guide the actual project, and help them save the construction time.

In the present paper, a study of furnace processes in the combustion chamber of the real energy boiler BKZ-160 of Almaty TPP-3 (Kazakhstan) using three-dimensional modeling methods has been carried out. Calculations of the combustion chamber for flame combustion of pulverized coal have been performed. The main purpose of this paper was to study the effect of fractional fuel composition on the concentration characteristics of the combustion process. Numerical simulation was carried out with two models of coal particle size distribution: monodisperse fuel flame (coal particle size identical and equal to 60 μm) and a polydisperse fuel flame (coal particle diameter varies from 10 to 120 μm). The polydisperse distribution corresponds to the fractional distribution (percentage of total coal particles) calculated for this boiler: the first fraction – 10% with dp = 10 μm; 20% with dp = 30 μm; 40% with dp = 60 μm; 20% with dp = 100 μm; 10% with dp = 120 μm. The numerical simulation results of the influence of the pulverized coal particle size composition on concentration characteristics of combustion process are presented. The distributions of oxidizer (oxygen) and combustion products (NO, CO, CO2) are shown. Areas with the greatest concentration of gas products of burning are determined, regularities of formation of products and their concentration at the exit of fire chamber are also determined. The effect of fractional fuel composition on the obtained characteristics is sufficiently large, the empirical data obtained directly at TPP-3 show better convergence with the result of the computational experiment that confirms simultaneously the adequacy of the used physical and mathematical statement of the problem, as well as the validity of using the model of polyfractional distribution.

The applicability of laser‐induced dye fluorescence (LIF) and rainbow schlieren deflectometry (RSD) for qualitative, non‐invasive real‐time visualization of spatial concentration distributions in two standard reference systems is presented. The combination of LIF and RSD enables measurements inside and outside of droplets and is able to overcome limitations of both measurement techniques. Experimental results in the presence of interfacial phenomena are compared and the connection between inner and outer effects is shown during droplet production at a capillary. [ABSTRACT FROM AUTHOR]

The author has formulated the problem of gravity stratification and formation of a sediment of a hydrodynamically low-concentration monodisperse suspension of solid particles not involved in Brownian diffusion and moving in a horizontal plane channel during the laminar flow of a Newtonian dispersed phase. A solution to the initial boundary-value problem for first-order partial differential equations has been obtained in analytical form by applying the one-sided integral Laplace transformation with respect to the axial coordinate. Using the principle of superposition of concentration fields of the fractions, the solution has been generalized to the case of a polydisperse suspension with an arbitrary particle-size-distribution density function. An estimate for the accuracy of physical linearization on replacement of the laminar flow of the carrier medium by an ideal-displacement regime has been given. A comparative analysis of computational experiments with classical experimental data for a wide range of the sedimentation Reynolds number has shown the correctness of the proposed approach. [ABSTRACT FROM AUTHOR]

Accidents involving natural gas leakage and dispersion pose a significant threat to human life and property. This threat is especially relevant at the street intersection at which dense buildings, heavy traffic flow, and complex underground pipe networks meet. Scholars have conducted numerous studies on gas leakage and dispersion, but investigations of natural gas leakage and dispersion at the street intersection of a building group are not in-depth. In this paper, we presented a three-dimensional (3D) physical model based on the Computational Fluid Dynamic (CFD) methodology to study the natural gas leakage and dispersion at the street intersection of a building group. We validated the CFD methodology applied in the research based on the data from the field tests and wind tunnel experiments. Then, we simulated and analyzed the pressure, wind, and concentration of natural gas dispersion at the street intersection. The simulation results showed that vortex regions, low-pressure zones, and a building group effect could cause a build-up of natural gas concentration under perpendicular wind direction conditions. In addition, the area of hazardous region tended to increase first and then drop with the dispersion height. In the case of this study, the maximum area of hazardous region is 200 m2 located in the height of 55 m, which is the middle plane in the computational domain. The results in the paper can provide scientific references for the safe operation and emergency-management decisions of municipal gas. [ABSTRACT FROM AUTHOR]

Sherardising is a surface protection method for obtaining an Fe-Zn coating on a steel surface by thermal diffusion. This paper proposes a model to study the sherardising diffusion process of low carbon steel. The diffusion mathematical model of the zinc coating element is established by the finite element method, which simulates the changes of zinc concentration field with temperature and time in the sherardising process. In the experimental work the sherardised samples were prepared for 2, 6 and 10 h at 375°C and 2, 6 and 8 h at 405°C and 420°C. Each phase's thickness and the zinc concentration of the sherardising layer were measured by scanning electron microscopy and energy dispersive spectrometry respectively. The results show that the accuracy of the finite element method is verified by the consistency between the simulation results and the experimental results. This model can effectively guide the sherardising process to achieve optimum results. [ABSTRACT FROM AUTHOR]

The spatial distribution of elements can be regarded as a numerical field of concentration values with a continuous spatial coverage. An active area of research is to discover geologically meaningful relationships among elements from their spatial distribution. To solve this problem, we proposed an association rule mining method based on clustered events of spatial autocorrelation and applied it to the polymetallic deposits of the Chahanwusu River area, Qinghai Province, China. The elemental data for stream sediments were first clustered into HH (high–high), LL (low–low), HL (high–low), and LH (low–high) groups by using local Moran’s I clustering map (LMIC). Then, the Apriori algorithm was used to mine the association rules among different elements in these clusters. More than 86% of the mined rule points are located within 1000 m of faults and near known ore occurrences and occur in the upper reaches of the stream and catchment areas. In addition, we found that the Middle Triassic granodiorite is enriched in sulfophile elements, e.g., Zn, Ag, and Cd, and the Early Permian granite quartz diorite (P1γδο) coexists with Cu and associated elements. Therefore, the proposed algorithm is an effective method for mining coexistence patterns of elements and provides an insight into their enrichment mechanisms.

Ensuring adequate ventilation during tunnel construction is a critical issue that directly affects construction efficiency. A good ventilation environment can effectively guarantee the construction progress. In this paper, by repeatedly selecting the flow field simulation parameters and continuously summarizing the calculation methods, a reasonable model is selected to simulate the tunnel engineering. Specifically, the eddy current zone near the working face is obtained by analysing the flow field of forced ventilation tunnels. Furthermore, we analyse the dispersion and accumulation of harmful gases in the tunnel. The CO concentration at typical locations in the tunnel is also examined in order to determine areas with the lowest likelihood of harmful gas discharge. We then propose adding a jet fan to the tunnel to create an extraction plus ventilation tunnel. Simulation results reveal that the addition of a jet fan causes eddy currents that improve the extraction of harmful gases, thereby greatly reducing ventilation time and increasing efficiency. The results of the model can effectively guide the actual project, and help them save the construction time. [ABSTRACT FROM AUTHOR]

Abstract Atmospheric pollution is a striking regional issue for public health and ecosystems and has major global impacts on climate. Particulate matter (PM) can be of primary or secondary origin and its sources, both natural and anthropogenic, are very heterogeneous in space and time. Hence, many efforts have been made worldwide to get a better knowledge of PM sources, in order to set effective reduction strategies. To this end, several distinct approaches may be used among which: (i) the localization of potential source areas with trajectory-based statistical receptor models (TRMs) which combine PM concentrations observed at receptor sites with computed back trajectories (BTs) of air masses, and (ii) the estimation of PM source contribution and chemical speciation with deterministic chemistry transport models (CTMs) based on emission inventories and detailed chemistry-transport processes. This study aims at testing the coherence between two independant approaches, CTMs and TRMs, for the geographical localization of the sources impacting a region of study. The case study refers to PM 10 pollution in the Hauts-de-France region (HdF) in the North of France for the year 2010. The considered TRMs are multi-site Concentration Field (CF) and Potential Source Contribution Function (PSCF) applied to 12 receptor sites using the Zefir package. The considered CTM is CHIMERE using detailed EDGAR European emission data. First, TRMs showed that some given far-located European countries (named "Far-East" countries) could have a strong but infrequent impact on PM 10 levels in the study region, while some given nearer European countries (named "Near-East" countries) had a frequent and predominant impact. Then, the contributions of each of these TRM-highlighted regions to PM 10 concentrations over the study area were analyzed by CHIMERE simulations. The potential influence of another non TRM-highlighted region (i.e. the "British Isles") was also studied for comparison. The CTM results confirmed the prevalence of the Near-East source area in terms of mass contribution throughout the year and particularly during high-concentration periods. Therefore results obtained from CHIMERE CTM and multi-site CF and PSCF TRMs showed consistency, highlighting the interest for further comparison of both CTMs and TRMs independent approaches in other regions as well as for other pollutants. Highlights • The continental and regional sources of pollutants impacting northern France are identified and quantified. • Two independent approaches, statistical sources-receptor and deterministic chemistry-transport models are used. • Both approaches showed consistency, highlighting the influence of several areas on the northern France pollution. [ABSTRACT FROM AUTHOR]

Abstract A novel reconstruction model based on inverse radiation analysis was presented for simultaneous estimation of temperature and concentration fields of soot and multiple metal-oxide nanoparticles in nanofluid fuel flame from the knowledge of the flame emission radiation intensity obtained by a CCD camera. The self-absorption effect was considered in the reconstruction model and least-square QR decomposition (LSQR) algorithm combined with iterative method was introduced to solve the inverse radiation problem. The inverse reconstruction model was successfully applied in the flames containing two and three kinds of metal-oxide nanoparticles from simulation values as examples and can be extended to more kinds of metal-oxide nanoparticles containing system. The measured data were also simulated by adding random noise into the exact solution of the direct problem. The numerical results showed that all the unknown parameters fields can be estimated accurately, even with the noisy data. [ABSTRACT FROM AUTHOR]

Abstract The inverse reconstruction method for the simultaneous estimation of temperature and concentration fields of soot and metal-oxide nanoparticles in asymmetric nanofluid fuel flame was improved by considering the self-absorption. The correction method to deal with the self-absorption in axisymmetric sooting flame for obtaining the unattenuated radiation intensity from the attenuated one detected by CCD camera was successfully extended to apply in asymmetric nanofluid fuel flame. These combustion parameters distributions can be concurrently deduced from the knowledge of the unattenuated radiation intensity using least-square QR (LSQR) decomposition and iterative methods. Self-absorption influences on the reconstruction accuracy in flames with different optical thicknesses were investigated and various levels of measurement errors were added into the simulation values from the practical experiment standpoint. The numerical results showed that the relative reconstruction errors of all the unknown parameters fields greatly reduced if self-absorption was considered in the reconstruction method. Moreover, as for the flame with larger optical thickness, the improvement of reconstruction accuracy was more significant. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present paper, a study of furnace processes in the combustion chamber of the real energy boiler BKZ-160 of Almaty TPP-3 (Kazakhstan) using three-dimensional modeling methods has been carried out. Calculations of the combustion chamber for flame combustion of pulverized coal have been performed. The main purpose of this paper was to study the effect of fractional fuel composition on the concentration characteristics of the combustion process. Numerical simulation was carried out with two models of coal particle size distribution: monodisperse fuel flame (coal particle size identical and equal to 60 µm) and a polydisperse fuel flame (coal particle diameter varies from 10 to 120 µm). The polydisperse distribution corresponds to the fractional distribution (percentage of total coal particles) calculated for this boiler: the first fraction - 10% with dp = 10µm; 20% with dp = 30µm; 40% with dp = 60µm; 20% with dp = 100 µm; 10% with dp = 120 µm. The numerical simulation results of the influence of the pulverized coal particle size composition on concentration characteristics of combustion process are presented. The distributions of oxidizer (oxygen) and combustion products (NO, CO, CO2) are shown. Areas with the greatest concentration of gas products of burning are determined, regularities of formation of products and their concentration at the exit of fire chamber are also determined. The effect of fractional fuel composition on the obtained characteristics is sufficiently large, the empirical data obtained directly at TPP-3 show better convergence with the result of the computational experiment that confirms simultaneously the adequacy of the used physical and mathematical statement of the problem, as well as the validity of using the model of polyfractional distribution. © 2018 University of West Bohemia. All rights reserved. [ABSTRACT FROM AUTHOR]

Abstract Trajectory-based statistical models (TMs) are widely used to locate source areas responsible for atmospheric pollution at receptor sites. In order to study the influence of long, medium and short-range back-trajectories (BTs) on geographical sources location, an original approach was applied to daily PM 10 concentrations measured for 5 years (2009–2013) at 12 receptor sites in the Hauts-de-France (HdF) region bounded on the south by the Paris megacity and on the north by the Benelux countries. The methodology used was based on two complementary TMs, Concentration Field (CF) and Potential Source Contribution Function (PSCF), and included several meaningful constraints in order to improve the spatial representativeness and the statistical significance of the potential source maps. The selection of BTs depending on the occurrence of scavenging precipitations (>1 mm h−1) during the transport of air masses and altitude limitations with respect to the planetary boundary layer height led to more realistic maps. The variability of the density of BT endpoints was accounted for by a weighting function which highlighted medium-distant yet recurring (e.g. Benelux and West of Germany) potential sources of PM 10. Investigating the effect of short-range BTs (75% of endpoints within a radius of 500 km from the receptor sites) pointed out at nearby large conurbations (Lille and Paris areas). Comparing our potential source maps with European PM 10 emission inventory maps as well as PM 10 measurements at European background monitoring stations for similar periods confirmed our results for Central Europe, the Benelux and the East of Germany. This study showed how the combination of several receptor sites enables the determination of potential source areas impacting a whole region. It pointed out also that the fine-tuned parametrization of the CF and PSCF TMs may considerably help improving the knowledge on geographical location of sources related to long, medium and short-range BTs and could be easily implemented for other regions of interest. Highlights • Use of constrained multisite trajectory-based CF and PSCF statistical models for PM 10 source localization. • Identification of potential sources from regional to continental scales depending on model constraining. • Realization of CF and PSCF maps of PM 10 potential sources impacting North of France over a 5-year period. [ABSTRACT FROM AUTHOR]