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The mobile flume has the advantages of not easy to be silted up and can be moved and reused in many places, etc. Compared with the fixed type, the streamlined shape of the measuring flume has good hydraulic performance, and the diffusion section of the flume has a great influence on the hydraulic performance, however, there is a lack of research on the design principle and method of the diffusion section at present. In order to study the influence of flume structure on hydraulic properties, and to provide theoretical guidance for the design of streamlined flume structure, This paper establishes a D40Ushaped channel simulation model, and then uses FLOW-3D to simulate the semi-elliptical with semi-elliptical, semi-elliptical with parabolic, semi-elliptical with arc, semi-elliptical with Myring curve, and fish-shaped flume under flow rates of 35, 45, and 55 L/s. Furthermore, the accuracy effect of numerical simulation is verified by prototype test, and then the design principle and method of diffusion section are discussed. Finally, based on the isight platform, the semi-elliptical with Myring curve and fish-shaped flume with better hydraulic performance are optimized. The results show that the relative error between the numerical simulation and the experimental water depth is 0.1%-1.3% and the relative errors of velocity in upstream, throat and downstream sections are 0.19%-6.63%, 0.06%-6.15% and 0.02%-6.22% at 45 L/s flow rate, respectively. The numerical simulation results have high accuracy. The Froude number in the upstream of the five flumes is less than 0.5, and the maximum backwater height is 5.71 cm, which meets the requirements of flow measurement accuracy and channel safety. Among them, the head loss and backwater height of the semi-elliptical with Myring curve flume are the lowest, the critical submergence degree of the semi-elliptical with semi-elliptical flume is the highest, and the Froude number is the smallest. The design principle of the diffusion section of the flume is: under the condition of slightly reducing the critical submergence degree, the first half of the diffusion section is designed as a curve with larger curvature to reduce the upstream backwater; the second half is designed as a curve with opposite curvature and smaller curvature to improve the flow state, smooth the water flow and reduce the head loss. After optimization, the curvature of the first half of the semi-ellipse with Myring curve and the fish-shape flume increases, and the curvature of the second half decreases, the backwater and Froude number are reduced, and the head loss is reduced by 5.5% and 6.3%, respectively. The study can provide theoretical guidance for the design and optimization of streamlined measuring tank structures. [ABSTRACT FROM AUTHOR]

Electro-induced deformation of water droplets is a complex physical phenomenon that involves coupling electric and fluid fields. It is commonly found on the surface of insulator fittings and equipment high-voltage equalizing rings after rain. Efficient and fast numerical simulation methods are the foundation for revealing the physical mechanisms of raindrop deformation and corona excitation. This article addresses the common problems of long calculation time and complex convergence in the numerical calculation of three-dimensional electric fluid models. A numerical simulation method based on field equivalence was proposed. Starting from the principle of light deflection, a water droplet deformation observation platform based on the shadow method is constructed. The effectiveness of this method was verified by comparing numerical simulation and experimental shooting results. The research results indicate that the relative error between the electric field constructed by this method and the original electric field is within 0. 01%. The spray morphology of water droplets obtained from numerical simulation under positive polarity DC voltage agrees with the experiment. By comparing the width and length of the water droplet root, middle, and head, it is shown that the relative error between numerical simulation and experiment is within 10%, verifying the effectiveness of the simulation method in this paper. At the same time, while ensuring convergence, the calculation time is reduced from 8 hours to 1 hour. [ABSTRACT FROM AUTHOR]

Reasonable support form and support parameters are the key to ensuring the stability of the roadway surrounding rock. The joint support effect of bolt + metal mesh + shot grouting in the Grade IV surrounding rock area of the drainage roadway of Julong Copper Mine in Xizang is poor. In this paper, for the problems of support in the Grade IV surrounding rock area of the drainage roadway of Julong Copper Mine, bolt and steel arch support, as well as the thickness of shot grouting, is introduced on the basis of the existing support. Different bolt support parameters are designed and optimized using finite element numerical simulation software. The results show that there is an obvious stress addition phenomenon at the roadway surrounding rock roof. With the increase of bolt support parameters, the maximum stress value at the roadway roof increases. With the increase of row spacing between bolts, the maximum displacement of the roadway roof increases, the bolt spacing increases from 1.2 m to 2.0 m, and the displacement of the roadway roof is 4 mm, 4.38 mm, and 4.82 mm, respectively. The optimal support parameter of the bolts is 1.6 m x 2.4 m. The results of the study provide theoretical references for the selection of the support parameters of the bolts of similar roadways. [ABSTRACT FROM AUTHOR]

Realizing quantitative evaluation of disaster reduction benefits of debris flow retaining dams has important theoretical and practical significance for optimizing engineering design and protecting the safety of people's lives. and property. The paper uses numerical simulation methods to obtain the mud depth, flow velocity, and range of debris flow under different operating conditions, establishes two risk evaluation index systems based on the area of high risk level and the total risk degree, proposes a quantitative evaluation method for the disaster reduction benefits of retaining dams, and conducts an empirical study using the Chutougou debris flow as an example. According to the evaluation method for disaster reduction benefits of retaining dams, it is possible to analyze the disaster reduction benefits of the proposed and existing projects and their combinations, determine whether they have achieved the disaster reduction goals, and compare and quantify the importance of different projects in disaster reduction, which can provide a basis and reference for the construction and improvement of debris flow retaining dams. The disaster reduction benefits per unit height can reflect the value of risk reduction per meter of retaining dam heightening, and can be applied to the determination of optimal engineering combination scheme of debris flow retaining dams. The change rule of the total risk degree and the disaster reduction benefits of the area with high risk level is consistent, indicating that both risk assessment methods can reflect the disaster reduction benefits of the combination of retaining dams and their changes. [ABSTRACT FROM AUTHOR]

The development of hydrogen energy industry is an important measure for China to achieve the goal of "carbon peak and carbon neutrality", accelerate green and low-carbon development, and comprehensively improve resource utilization efficiency. Compared with high-pressure gaseous hydrogen storage, solid hydrogen storage and other hydrogen storage methods, low temperature liquid hydrogen storage has the advantages of high effective hydrogen storage density, low transportation cost, high vaporization purity and low storage and transportation pressure, so it is the most potential hydrogen storage method for high-power fuel cells. In this paper, Fluent is used to perform unsteady calculations on the liquid hydrogen supply system of a high-power marine fuel cell, and study the minimum gas hydrogen charging speed required to completely discharge the liquid hydrogen in the tank within a given time. The numerical simulation results show that during the process of high-temperature gas hydrogen filling into the liquid hydrogen tank, there is a local high temperature at the entrance due to heat accumulation. The hydrogen enters the liquid hydrogen tank and flows in the horizontal direction, flowing downward under the action of gravity and the wall, and through the convection heat transfer with the low-temperature fluid in the tank, it will change the fluid density in different areas, so that the gas hydrogen and liquid hydrogen produce vortices respectively. [ABSTRACT FROM AUTHOR]

Based on the theory of Darcy, s law and solute transport, this paper took a ground water-sealed oil depot project on a certain island as the engineering support and conducted numerical simulation research using COMSOL finite element software to analyze the variations in seepage field in caverns under different design schemes. The water-sealed safety of the cavern was evaluated. The development degree of seawater intrusion in the reservoir area was explored. The research indicated that the project required the installation of a horizontal water curtain, and the design pressure value of the horizontal water curtain should not be less than 0.2 MPa. The variation in the depth of the main cavern had a small impact on the water seal, and the recommended buried depth was -45 m. When the main carvern was fully excavated without oil storage, seawater would intrude into the caverns, with seawater intrusion showing a pattern of rapid intrusion followed by gradual intrusion, entering from the bottom of the main cavern. [ABSTRACT FROM AUTHOR]

Crack propagation velocity is a crucial discussion for understanding dynamic fracture. Classical dynamic fracture theory predicts a “forbidden velocity zone” for mode Ⅱ cracks, i.e., the velocity between the Rayleigh and shear wave speeds. However， supershear transition has been demonstrated theoretically and experimentally for mode-Ⅱ crack constrained to weak interfaces. Such transition is commonly accepted to be governed by the Burridge-Andrews mechanism (also known as “mother-daughter” crack), which predicts direct nucleation of a secondary intersonic daughter crack induced at the Rayleigh wave speed. Nevertheless, to our knowledge, “mother-daughter” crack pairs are rarely reported with visual observations, and the supershear rupture without the daughter crack forming has also been found in some previous reports. Recently, Prof. Liangbin Li ’s group at University of Science and Technology of China and the coworkers reported the Sub-Rayleigh to supershear transition of dynamic mode-Ⅱ cracks based on numerical simulations. Their numerical experiments successfully reproduced the “mother-daughter ” cracks for the first time in phase-field fracture modeling, as well as the supershear transition without the daughter crack. Given that, a crack tip blunting-tearing hypothesis was presented to explain that cracks comply with different mechanisms from Sub-Rayleigh to supershear regimes, and a critical prestress level was revealed below which no supershear transition can be accomplished from the Sub-Rayleigh propagation. Furthermore, the criteria were also proposed for predicting the occurrence of the daughter crack through systematic simulations. This paper briefly presents their progress in the studying of the Sub-Rayleigh to supershear transition for dynamic mode-Ⅱ interfacial fracture. [ABSTRACT FROM AUTHOR]

The inhomogeneity of the lake and land underlying surfaces has large influences on the development and evolution of severe convective weather. Poyang Lake is the largest freshwater lake in China, and its area exhibits distinct monthly and seasonal variations. However, the underlying surface of the lake in the Weather Research and Forecast (WRF) model is usually assumed to be constant, which is different from the real situation and leads to model forecast errors. In this paper, the WRFV3.9 model was used to simulate a severe convective weather event that occurred over the Poyang Lake region during a summer night. Lake area sensitivity experiments were conducted to analyze the influence of Poyang Lake on the development and evolution of severe convective weather and its mechanism. The results showed that the 2 m temperature over the lake surface was significantly higher than that over the land surface during summer night. The land breeze converged and rose over the lake region, while there was a sinking and divergent airflow over the shore, which caused precipitation to decrease over the west bank of the lake but increased over the lake. The subsequent lake-removing sensitivity experiment further confirmed the warming effect of Poyang Lake. Poyang Lake could inhibit precipitation occurred over the west bank of the lake and intensify precipitation over the lake by stimulating the secondary circulation of land-breeze. The precipitation of the lake-removing experiment increased by 20% over the west side of the lake, and decreased by 16% over the lake, suggesting the impact of the lake on precipitation intensity. In addition, it was found that the precipitation over the lake increased by 7%, 16%, 30% and 43% in the lake-expanding sensitivity experiments, where the lake area was expanded by 1.5, 2.5, 3.5 and 4 times, respectively, further confirming the sensitivity of severe convection intensity to the area of Poyang Lake. These results indicated that attention should be paid to the possible trend of convections weakening (enhancing) before (after) entering the Poyang Lake region during summer nights. Meanwhile, when a numerical model was used to simulate the severe convection weather, the real lake area could be introduced into the underlying surface of the model when the real lake area differed greatly from the default climatic value used in the numerical model, to improve the forecasting capability for severe convective weather occurring over lake regions. [ABSTRACT FROM AUTHOR]

Sewage treatment is one of the main contents of environmental protection, so it is very important to provide a theoretical basis for sewage treatment through the analysis of the mechanism. Based on the classical material conservation mathematical model of microorganism and substrate, this paper analyzed the existence and stability of each equilibrium point of the model by calculating the Jacobian matrix of the model, and gave the sufficient conditions to make the stability of the equilibrium point of the model. The numerical simulation method is used to effectively verify the analysis results. In order to improve the effect of sewage treatment, we put forward some suggestions on the setting of relevant parameters in the sewage treatment process from the perspective of mathematical analysis, and verified the correctness of the suggestions by numerical simulation method. [ABSTRACT FROM AUTHOR]

Aiming at the problems ol slow filling elliciency and low and unstable sand discharge concentration in the traditional vertical sand silo working mode, a continuous high-concentration and stable sand discharge working mode is proposed, and the maintenance ol sand storage height is the key to this working mode. In this paper, the centrilugal test is used to investigate the lunctional relationship between the underllow concentration and the sand storage height, and then the static settlement test is used to obtain the feeding parameters, and the hydro dynamic software is used to simulate and analyze the sand storage process ol the vertical sand storage,to verily the feasibility ol the functional relationship, and the dynamic mesh technology is used to simulate and monitor the sand discharge concentration, overllow concentration and sand surlace height change ol sand discharge process with dilierent storage heights, and to investigate the optimal sand storage height, and to provide a comprehensive solution to the problem. The simulated monitoring ol sand discharge concentration and sand surlace height changes during sand discharge at dillerent storage heights using dynamic grid technology is used to comprehensively investigate the optimal sand storage height, which provides an important reference lor the study ol continuous sand discharge Irom vertical sand silo. The results show that:there is no significant dillerence between the numerical simulation and the lunctional relationship, and the lunctional relationship between the underllow concentration and the sand storage height is feasible； 11. 8m is the optimal sand storage height lor the vertical sand silo to continuously discharge sand with high concentration and stability. [ABSTRACT FROM AUTHOR]

Rainfall infiltration can cause a decrease in the strength of the rock and soil mass on the dump slope, increase the bulk density of the upper rock and soil mass, and reduce the stability of the slope. This paper takes a mine dump slope as the background, and uses GeoStudio software to simulate and analyze the pore water pressure characteristics and safety factors under different rainfall durations. The simulation results indicate that as the duration of rainfall increases, the limit value of pore water pressure continuously increases, and the pore water pressure increases towards the top of the slope, while the corresponding safety factor decreases. The study provides references for the stability of the dump slope in the mine. [ABSTRACT FROM AUTHOR]

In order to ensure the safety and reliability of the foundation pit support project and the feasibility of the overall construction of the project. Based on the cohesive soil characteristics, this paper mainly uses the inclinometer to measure the displacement of piles and retaining structures and conduct numerical simulation. The results show that during the test period, the excavation support displacement only shows a stable growth mode in the first two months, and then gradually flattens to the final stable state. The safety factor Msf is calculated through numerical simulation, and it is obtained that the reduction of relevant geotechnical parameters makes the safety factor Msf of pile higher than that of retaining structure; And with the increase of time, the pile displacement increment is lower than the support displacement increment. [ABSTRACT FROM AUTHOR]

Steam assisted gravity drainage（SAGD） heavy oil development technology is influenced by development factors and geological factors, among which reservoir thickness is an important factor affecting the development of steam chamber and the state of steam, water and oil interface inside the steam chamber. The two main steam-assisted gravity drainage models are the double horizontal well model and the vertical-horizontal well combination model. In this paper, combined with the actual production data of Guantao block in Liaohe oilfield, the conceptual model under multiple well groups was established by using CMG-STARS software, and the control variable method was used only to change the single factor of reservoir thickness. The influence of reservoir thickness on the development effect of steam assisted gravity drainage was analyzed comparatively. In the case of the well group in this conceptual model,a thickness of around 50mis a threshold for variation in the effectiveness of SAGD development.In the early stage of SAGD development,the thickness of the double horizontal well is about 55m.In the later stage of development,the greater the thickness,the better the effect.The higher the reservoir thickness is,the better the effect is.When the reservoir thickness is more than 50m,the improvement trend of injection and production effect becomes relatively slow. [ABSTRACT FROM AUTHOR]

As a new type of clean energy, wave energy has great prospects for efficient use of wave energy power. When it comes to oscillating buoy wave energy devices, many countries have put prototypes into use, and the technology of wave energy has broad development prospects. In order to clarify the hydrodynamic characteristics of the multi buoy truss-type wave energy convertor (WEC) platform, the mathematical model was established by using the high-order boundary element method based on potential flow theory, in which the buoy and the platform were connected by the lever principle. The mathematical model was applied to study the heave motion response of each buoy of the multi oscillating buoy truss-type WEC platform, and the effects of the buoy number and arrangement on the motion responses of buoys, as well as the power generation of the WEC platform were analyzed. The time history curves of buoy motion speed under the influence of different linear PTO damping coefficients C were calculated, and the optimal power generation efficiency of the multi buoy WEC power generation device was determined. Through the mathematical model established in this paper, some useful conclusions on the hydrodynamic characteristics of WEC platforms have been obtained, which can provide data reference for relevant wave energy platform. [ABSTRACT FROM AUTHOR]

In order to study the evolution of aircraft wake vortices more deeply and precisely, and to ensure the safe operation of aircraft, the dissipation law of A330‑300 aircraft wake at different temperature vertical decreasing rates is studied in this paper by numerical simulation. The shear stress transport (SST) k‑ω turbulence model is chosen for the numerical simulation. The temperature field under five different temperature vertical decreasing rates is constructed, and the A330‑300 aircraft wake flow field is compiled within the temperature field to realize the calculation under different temperature vertical decreasing rates. The reliability of the numerical simulation method is verified by comparing the numerical simulation results with the radar detection data. The results show that for general turbulence intensities, different rates of vertical decreases in temperature act mainly on the decay phase of the wake, affecting the evolution of the wake by changing the temperature inside and outside the wake.The smaller the temperature vertical decreasing rate is, the larger the rate of decrease of circulation in the wake vortex decay region is. The larger the vertical rate of temperature decreases, the larger the rate of tail vortex sinking is and the larger the distance between vortex cores after rapid dissipations is. [ABSTRACT FROM AUTHOR]

The hydrodynamic model experiment results of trawling otter board often have different degrees of deviation due to various experimental factors such as Reynolds number and model scale ratio. To understand the Influence mechanism in the hydrodynamic model experiment of otter board, this paper selects vertical cambered V-Type otter board as the research object, bases on the flume tank model experiment combined with computational fluid dynamics (CFD) numerical simulation method, the hydrodynamic performance and flow field distribution were compared and analyzed, aims to explore the influence of model scale ratio, board thickness and model material on its hydrodynamic performance experiment. The results show that the change of model scale ratio has no significant effect on the curve shape of lift coefficient and drag coefficient, but excessive reduction of model scale ratio (20 ∶1) will lead to significant deviation of lift coefficient at the small angle of attack ( α < 30°). The change of the board thickness will lead to a significant change of the lift coefficient at the large angle of attack (α> 30°), while the influence on the drag coefficient mainly reflects on the small angle of attack ( α < 30°). Non-metallic material model is insufficient rigidity, and it is easy to produce certain displacement and deformation after obtaining stress in the flume tank model experiment process, which will cause the deviation of experimental results. Based on the above results, the model scale should be as large as possible to reduce the influence of model scale on the accuracy of experimental results. The structure stability of the model can be improved by increasing the board thickness, but the thickening range should not be more than double of the prototype. [ABSTRACT FROM AUTHOR]

In order to better integrate mineral resources in the mining area and improve mine production capacity and economic benefits, a mine plans to implement phase Ⅱ project construction（mining area Ⅱ） when the mineral resources of phase Ⅰ underground project（mining area Ⅰ） are to be nearly depleted. The paper carried out an engineering geological survey on the typical ore rock in the study area in order to demonstrate the impact of the construction of connecting roadway from mining area Ⅰ to mining area Ⅱ on the overlying rock layers of surface villages. Based on the results of on-site engineering geological survey, indoor rock mechanics test, and rock mass quality evaluation, the numerical simulation analysis research on the impact of newly excavated roadway on surface deformation is carried out. The results show that the excavation of the roadway connecting mining area Ⅰ and mining area Ⅱ only results in minus 10 mm surface displacement and will not damage the overlying rock layers of the surface villages. [ABSTRACT FROM AUTHOR]

In order to reduce the harm of dust and CO produced by tunnel blasting to the construction personnel, this paper puts forward an auxiliary ventilation method by adding the following portable gas exhaust device in the tunnel. In order to determine the effectiveness of the portable gas exhaust device, this paper simulated the application scene and application effect of the device based on the Numerical simulation software Fluent in Jiming Tunnel engineering, and obtained the tunnel flow field, dust and CO migration rule after the injection ventilation and the addition of the exhaust device. And the effect of the device on the flow field was verified, and the effect of the device on accelerating the discharge of dust and CO was verified. After the addition of the device, the change rule of CO concentration with time at five measuring points away from the palm surface was linearly fitted. The results show that: The addition of the following harmful gas exhaust device can effectively accelerate the discharge of dust and CO in the working area of the palm face. Within 120s of ventilation, the concentration of dust and CO in the same position after the addition of the device at the same time point is far lower than that under the pressure ventilation condition. After the addition of the device, the dust and CO concentration within 5m in front of the palm of 110-130s can be ventilated below the safe concentration. At the same time, the addition of the device will increase the disorder degree of the tunnel flow field to a certain extent. After the addition of the exhaust device, the change of CO concentration at the five measuring points in front of the palm of 30min of ventilation meets the single exponential function. Comparing the changes of dust and CO concentration before and after adding the portable harmful gas exhaust device, the effectiveness of the device was verified. [ABSTRACT FROM AUTHOR]

Stepped slope protection can not only meet the needs of cultural landscape, but also has a good effect of reducing waves. In recent years, it has been applied in some dam projects, but there is still a lack of systematic research on relevant design parameters. In this paper, a two-dimensional numerical wave model was established based on the velocity boundary method according to the medium and large reservoir dams. The influence of step layout range, step size, dam slope degree and wave smoothness for wave run-up was analyzed. The results show that, compared with the smooth slope protection, the stepped slope protection can effectively reduce the wave run-up. For the same wave smoothness and dam slope degree, the wave run-up decreases with the increase of step layout range, and decreases first and then increases with the increase of step height. The recommended step layout range is 1 times the wave height above the free water surface to 2 times the wave height below the free water surface. The recommended step height is 0.4 times of the incident wave height, and the wave attenuation coefficient is between 60% and 70%. In the recommended stepped slope protection arrangement, the wave run-up increases with the increase of wave smoothness and decreases with the softening of dam slope. When the slope is lower than 1∶3.0, the influence of slope coefficient on wave run-up weakens to some extent. According to the comprehensive roughness and osmosis coefficient calculated in this paper, the wave run-up of stepped slope protection can be estimated preliminarily, which provides reference for similar engineering design. [ABSTRACT FROM AUTHOR]

The camera system for monitoring the combustion in the cremator needs to work normally at a safe temperature. In order to predict whether the monitoring camera is in a safe state to work normally when the cremator is working, the flow and heat transfer characteristics of the endoscopic high-temperature camera system of cremator with air cooling are numerically studied by the ANSYS FLUENT software in this paper. The numerical simulation results show that the high-temperature camera system can work normally by only air cooling only, and the minimum compressed air flow rate required to ensure the normal work of the camera system under different wall temperatures is obtained. The research results have certain reference value for the design of the endoscopic high-temperature camera system of the cremator. [ABSTRACT FROM AUTHOR]

Cadmium zinc telluride (Cd1-x Znx Te, referred to as CdZnTe or CZT) is a room-temperature nuclear radiation detection material, which is promising for use in the fields of medical imaging, environmental monitor and space exploration, due to its superior photoelectric properties. Traveling heater method (THM) is considered to be one of the most promising methods for growing CZT single crystals. During the crystal growth, a suitable temperature field is a prerequisite for obtaining high-quality crystals. In this paper, the Fluent software is used to study the thermal field of a resistance-heated THM growth system. A physical and mathematical model describing the thermal transport of the system is established, and an inverse simulation method for establishing temperature control points is proposed to solve the problems of the heaters' power. The calculated values of the power of five heaters in the furnace are 225. 6, 343. 7, 1 045.9, 92.5 and 199.6 W respectively, which are in good agreement with the experimental measurements. Furthermore, the effects of furnace structures such as the distance between the heater and the heating tube, and the width of the heat-dissipation zone on the temperature distribution in the CZT zone in the crucible were studied. The research results show that the maximum temperature decreases by 3. 7% and 5. 6% when the distance between the heater and the heating tube increases from 5 mm to 10 and 15 mm, and the width of the melting zone decreases by 32.7% and 50.0% when the width of the heat-dissipation zone increases from 30 mm to 50 and 80 mm. [ABSTRACT FROM AUTHOR]

To investigate the influence of the orifice plate on the freezing efficiency of fish in the impingement blast freezer, this paper takes yellow croaker as the research object, analyzes the effects of different orifice plate arrangements, hole diameter and air supply distance on the freezing efficiency of fish, and obtains the fish temperature distribution and the evolution of central temperature with time. The results demonstrate that the staggered arrangement of the upper and lower orifice plates avoids wind hedging, so the freezing rate is the highest and the freezing time is the shortest. Increasing of the orifice plate diameter effectively reduces the fish freezing time in the second stage and the cooling time in the third stage. The shorter the distance between the upper and lower orifice plates from the center of the fish body, the shorter the fish freezing time. The study shows that:screening the structure and parameters of the air supply orifice plate with suitable purpose can provide new process guidance for the freezing of aquatic products and provide technical support for the optimal design of the impact freezer. [ABSTRACT FROM AUTHOR]

Based on the precipitation data of automatic weather stations, CMA-STI and ERA5 data from 2000 to 2020, this paper found that, less than half of the tropical cyclone activities were accompanied by heavy rain that occurred in the Jianghuai region, and only 30% of the tropical cyclones were in the company of daily precipitation in the Jianghuai area reaching the average daily amount in the Meiyu period of that year. Except for a few "path-turning type" tropical cyclones and "northwest-traveling type" tropical cyclones that continued to move eastward or northward after landfall, most of the other tropical cyclones were accompanied by the weakening of Meiyu. The WRF model and the built-in TC bogus method were used to simulate the 2017 typhoon Merbok and the 2019 typhoon Danas to verify the influence mechanism of TC on Meiyu. The results show that the model well simulated the path, precipitation area and intensity of the two typhoons. By comparing the tests before and after the removal of the typhoons, it was found that the "northwest-traveling type" typhoon Merbok strengthened a low-level jet with the westward airflow at the southern edge at the early stage, a Yangtze-Huaihe valley shear strengthened, a low pressure headed northward after landing, and a subtropical high was stable, forming a circulation situation favorable for precipitation. After removing Merbok, the low-level jet broke, the subtropical high retreated southward, the water vapor in the South China Sea could not be transported to the Yangtze-Huaihe valley, and the precipitation in the middle and lower reaches of the Yangtze River decreased. With the northward movement of both the path-turning type typhoon Danas and the the subtropical high, convective instability decreased and vertical ascending motion weakened. A large amount of water vapor from the western Pacific was transported to the vicinity of the typhoon eye. The water vapor transport and precipitation in the Yangtze-Huaihe valley decreased and the Meiyu was interrupted. After removing Danas, the precipitation in the east increased, the subtropical high was stable, and the Meiyu was maintained. [ABSTRACT FROM AUTHOR]

Large-diameter pile group foundations have the characteristics of high bearing capacity, and have broad application prospects in large-scale engineering foundations in soft soil areas. Based on the field test data of vertical bearing capacity of a bridge group pile foundation, the ABAQUS numerical calculation platform is used to calculate and fit the soil parameters. Based on the soil parameters obtained from the fitting, the bearing characteristics of the piles under the horizontal load are calculated and analyzed, and the bearing characteristics of the group pile foundation under vertical and horizontal loads are also studied. The results show that when the maximum vertical load acts on the cap-pile group foundation, the maximum displacement of the cap is 84.83 mm, and according to the displacement control principle, the upper limit of the pile group effect is 83%, and the lower limit is about 62.8%. Under the vertical load, there are differences in the settlement value of each pile in the pile group, the center piles are the largest, followed by the side piles, the corner piles have the smallest settlement. With the load gradually increased, the displacement differences of the corner piles, the side piles and the center piles show a trend of first increasing and then decreasing. When the maximum vertical load is applied to the group pile foundation, the horizontal influence range of foundation horizontal displacement is about 1.5 times of the side length of cap, and the maximum influence depth is about 1.5 times of the side length of cap. The soil between piles shows tension shear stress in the range of 0.5 times of side length of cap below the ground surface. This paper analyzes the bearing characteristics of pile groups under horizontal and vertical loads and its conclusions can be used for reference for relevant engineering design. [ABSTRACT FROM AUTHOR]

Coupled heat and moisture simulation of porous building materials has been widely used in building simulations. However, while underground buildings have received increasing attention with the scarcity of urban land, the related hygrothermal studies have received little attention, mainly because of the complex hygrothermal loads inside underground buildings and the large surrounding soil area included in the simulation. In order to accurately predict and optimize the hygrothermal performance of underground buildings and guide its hygrothermal simulation. By means of a scoping paper review, the theoretical approaches to heat and moisture transfer were reviewed. The results and deficiencies in the current stage of heat and moisture simulation of underground buildings from the perspectives of mathematical models, simulation tools, and boundary conditions were summarized. The results show that the challenges of coupled heat and moisture simulations for underground buildings lie in the uncertainty of soil composition and moisture, rainwater deposition and moisture migration on the soil surface, and the huge computational costs associated with large soil domains. The two-step approach, while simplifying the simulation, is not sufficient for hygrothermal simulations. There is a need to identify a recognized procedure / method to determine the exterior boundary conditions for underground envelopes to reduce the simulation complexity. [ABSTRACT FROM AUTHOR]

Harbors located in swell dominated seas may encounter problems such as inefficient performance of breakwaters and harbor oscillations. Taking a specific sea port in Chancay Bay, Peru, as an example, the performance of a breakwater and the characteristics of harbor oscillations are analyzed by numerical simulations. The results show that the breakwater is capable of providing protection against swell and the ratio of the wave heights inside and outside the harbor is approximately 0.15. The operational efficiency and safety at berth are guaranteed according to the tolerable wave height of short waves. The reduction of infragravity (IG) waves after they propagate into the harbor is negligible. Considerable downtime may be expected according to the tolerable IG waves. Therefore, IG waves should be taken into consideration during the design of harbor layouts and mooring systems and particularly, the natural periods of the mooring systems should not be close to the periods of IG waves inside the harbor. The results of the study presented in this paper may offer reference for the design of harbour layout and mooring system. [ABSTRACT FROM AUTHOR]

In order to further understand wood transverse cutting performance, optimize wood processing process and reduce resource waste, based on wood tracheid theory, this paper proposed a model of wood helical tracheid structure, and carries out transverse cutting simulation study in Abaqus/ Explicit after modeling and representative volume element (RVE) uniformity. Picea abies was selected as the test material to conduct modeling based on the helical tracheid structure. Model attributes, boundary conditions, mesh division and assembly were set for simulation and post-processing. Relevant data were derived and compared with the conventional structural model simulation results and actual experimental results. The results showed that the simulation results based on helical tracheid structure were closer to the actual experimental results than the conventional structural model simulation results, which provided a favorable reference for future wood simulation research and wood processing optimization. [ABSTRACT FROM AUTHOR]

The dangerous rock mass is widely distributed in southwest China, and is easy to formate collapse for many times. In order to study the collapse disasters reported in the terrain, the accumulation of subsequent collapse rockfalls characteristics, this paper, by using multiphase collapse simulation method, can reflect the changing situation and the threat range of the deposit after many times collapse according to certain probability, and supplement the deficiency of the conventional calculation result of once collapse of stones. It provides a scientific basis for the prevention and control of geological disaster in the study area in the following period. This paper takes the Xujiadabang collapse in Sinan County, Guizhou Province as an example. The multi-stage numerical simulation of unstable rock collapse is studied based on laboratory tests and numerical simulation, combined with GIS technology and 3D collapse software. The numerical simulation results of four stages of collapse by using the characteristic parameters obtained from physical experiments are in good agreement with the field investigation results. It is found that almost all of the large size rockfalls and most of the small size rockfalls are deposited in the area with a slope less than 35°. More than 90% of the rockfall deposits in the 30 m buffer zone on the abandoned road surface, that is, 100 m away from the residential area. The percentage of rockfall deposits in the direction of the abandoned road toward the cliff shows an upward trend. The nearest large particle size rockfall is mainly 60 m away from the residential area, and the possibility of threatening the residential area is low. A small number of small particle size rockfalls will fall to the residential area. The research ideas and technical methods in this paper have reference values and significance for the study of multi-stage dangerous rockfall. [ABSTRACT FROM AUTHOR]

At present, the research on the rock fracture propagation of middle and deep geothermal energy is mainly carried out for a single fracture, while in the actual mining and production process, the rock fractures are mostly complex fracture network, and the single fracture research is difficult to guide the field actual engineering. In this paper, based on the cohesive force model of the cohesive element, using the finite element commercial software ABAQUS, and based on the results of the thick wall cylinder expansion fracturing experiment, the fracture propagation path is prefabricated. On this basis, the rock multi fracture network propagation model is established, and the relevant numerical simulation calculation is carried out to analyze the fracture initiation time, maximum principal stress, pore pressure The influence of many factors, such as crack width, on the crack propagation is analyzed, and the propagation law of multi crack seam net is obtained. The results show that the crack initiation time has an effect on the maximum principal stress and pore pressure, but has little effect on the crack width. Compared with the simultaneous initiation of fractures, the successive initiation of fractures will increase the maximum principal stress and pore pressure, which is conducive to the formation of multi fracture network. However, the crack width cannot be increased by controlling the initiation time. [ABSTRACT FROM AUTHOR]

As the main leakage pathway in CO2 sequestration, the sealing integrity of the abandoned wellbore is directly related to the sequestration effect. To this end, for the abandoned wellbore leakage problem, a three-dimensional finite element model of cement plug-formation is developed based on the cohesive zone method coupled pore pressure. In this paper, we simulated the CO2 transport process along the abandoned wellbore and analyzed the influence of cement slurry system and bonding quality on the risk of leakage. The simulation results show that: CO2 accumulation induces micro-annulus at the plug-formation interface, forming a leakage channel, and the micro-annulus tends to develop axially; the risk of wellbore leakage is lower when choosing higher modulus, higher Poisson's ratio, and micro-expansion cement to seal the wellbore; the micro-annulus is extremely sensitive to the poor bonding zone, and the control of bonding quality should be focused when sealing the wellbore. The results of this study have important implications for guiding wellbore abandonment within the CO2 sequestration block. [ABSTRACT FROM AUTHOR]

In the modern textile industry, the air-jet loom has developed rapidly with its advantages of high speed and success rate of weft insertion. During air flow insertion, the air-jet loom relies on the high-speed airflow from the main and auxiliary nozzles to pull the weft yarn, and the weft yarn is straightened and quickly passed through the weaving mouth. This weft insertion method makes the yarn move quickly and steadily in the weft insertion flow field and realize high-speed and efficient weft insertion. Since the air-jet loom is of semi-open structure, a large amount of compressed gas consumption is generated during the process of intersection of airflow. Furthermore, the integration of the auxiliary profiled reed and the airflow channel involves complex shapes and high cost, which makes it difficult to adapt to the requirements of frequent fabric changes. Therefore, in response to the national carbon neutrality and carbon peak policy, the realization of green manufacturing, the reduction of gas consumption in the weft insertion process of air-jet looms has become the focus of air-jet weft insertion process innovation. In this study, a new sheet-type multi-source air-jet weft insertion technology was proposed for reducing the gas consumption in the process of weft insertion based on the original pipe sheet-type weft insertion process. Firstly, a new air-jet weft insertion channel was designed, and the flow field simulation model of the new channel was established. Secondly, the flow field characteristics of the new insertion channel at 0.2, 0.3 and 0.4MPa pressure levels were numerically analyzed. Finally, the experimental platform was built to verify the reliability of the simulation results, and the airflow velocity at the central axis of the flow field was obtained to be compared with the numerical simulation results. The study shows that the maximum velocities of in the new insertion channel are 93.42 m/s, 127.35 m/s and 151.57 m/s at the pressure levels of 0.2, 0.3 and 0.4 MPa, respectively, and the maximum velocities of the sheet-type multi-source weft insertion technique are increased by 19%, 5% and 2%, respectively, compared with the conventional air-jet weft insertion technique, and the decreasing trends of the velocities are similar to those of the conventional air-jet technology. In addition, the gas consumption of the sheet-type multi-source technique is 1.24 g/s and 1.57 g/s at the pressure levels of 0.3 and 0.4 MPa respectively, 8.4% and 8.7% lower than that of the conventional air-jet weft insertion technology. In this paper, the flow field simulation analysis and experimental verification of the proposed thin sheet multi-source air-jet weft insertion technology are carried out. However, the influence of the main nozzle air flow is not considered, and the devices among the sheets at high-speed situation are ignored. The analysis of the synthetic flow field characteristics of the main nozzle and weft insertion channel and the applicability of the devices at high-speed situation mode are to be researched. [ABSTRACT FROM AUTHOR]

In order to study the influence of air and water media on pre-crack blasting, the single-hole blasting damage of the marble HJC intrinsic model and the porous burst seam condition under different uncoupling coefficients were studied through LS-DYNA software. The results show that: 1) Under the same uncoupling coefficient, the damage range of water uncoupled charge is larger than that of air uncoupled charge. With the increase of the radial uncoupling coefficient, marble under the condition of the air uncoupling charge and water uncoupling charge damage range will gradually decrease. It can effectively protect the hole wall rock mass. 2) The stress propagation law of water uncoupled charge and air uncoupled charge is the same, but water uncoupled charge has a higher utilization rate of explosive energy than air uncoupled charge. 3) According to the rock conditions in this paper, the optimal blasting parameters are obtained, and a good pre-crack blasting effect is achieved in the field. [ABSTRACT FROM AUTHOR]

Aerodynamic system is an important part of a grain cleaning equipment. In this paper, the literature classification method is used to classify and study the literature, and the application and research progress on aerodynamic technology in grain cleaning are analyzed and summarized, so as to provide reference and guidance for the application and development of aerodynamic grain cleaning technology. In order to achieve the goal of grain cleaning, the corresponding cleaning methods are adopted in different cleaning occasions. However, the air flow characteristics and grain particle characteristics have significant influence on the cleaning effect of grain cleaning based on aerodynamics. When the variation range of grain particle characteristics is certain, the adjustment amount of cleaning equipment and the feeding amount were unchanged, the factors affecting the cleaning efficiency of grain were counted. The distribution form, uniformity, and stability of aerodynamic field had a direct influence on the cleaning effect of grain. In the work of grain cleaning, the key of grain efficient sorting is to clarify the distribution law and influencing factors of air flow stability and uniformity in the aerodynamic field, clarify the action mechanism of grain grading weight, and ensure the uniformity and stability of the aerodynamic system and the match of the whole cleaning system. [ABSTRACT FROM AUTHOR]

A large number of residual ores in the intermediate pillars, crown, and sill pillars left by the shrinkage mining process adopted in the upper deposit of Chaihulanzi Gold Mine are highly economically valuable.To further improve the utilization rate of residual ore resources, this paper based on the existing scheme of the mine proposes 4 overall mining technology schemes for residual ore resources.Based on ABAQUS numerical simulation software, the corresponding numerical simulation model is established.The size striking direction extends 420 m, the vertical direction 616 m, and the height 160 m; the width of the surrounding rock is 50 m.The recovery rate, displacement field, and surface subsidence of different schemes were obtained, and the optimal technical extraction scheme was finally determined to be the horizontal and vertical striped evenly supported ore pillar extraction scheme through comparative analysis.The results show that in actual production, the scheme can maximize the economic benefits under the condition of safe mining while recovering the residual mineral resources under the non-cemented waste rock filling body. [ABSTRACT FROM AUTHOR]

The support of complex and fractured surrounding rock tunnels is one of the challenges that should be dealt with urgently during the development process of deep gold resources. At present, mines often use joint support methods with steel arch frames and wood. However, due to the inflammable and easily corrosible properties of wood, it is not applicable for permanent underground mine support. Therefore, based on the numerical simulation study, this paper proposes to use new type of support materials with lightweight energy-absorbing characteristics as the lining to replace the wood in the support of tunnels.The theoretical analysis shows that the new type of support materials has obvious energy absorption and pressure relief effects and is more suitable for the pressure relief support system for complex and fractured tunnels. [ABSTRACT FROM AUTHOR]

In order to optimize the total water inflow of foundation pit dewatering, obtain the optimal single well water yield and the optimal number of dewatering wells, an optimization model of foundation pit dewatering based on objective function method was established in this paper. Meanwhile, taking the headwork inverted siphon foundation pit dewatering project of Xixiayuan Water Conservancy and Irrigation Area Project in Henan Province as an example, the optimization model of canal foundation pit dewatering in inverted siphon section was established by using the objective function method, and MATLAB optimization toolbox was used to optimize the solution of the canal foundation pit dewatering model of the project example, and GMS numerical simulation software was used to verify and analyze the optimization results. The optimization results show that: under the condition of meeting the construction requirements of the foundation pit and the safety conditions of the surrounding environment, compared with the initial scheme, the total water yield can be reduced by 624 300 m³ and 546 390 m³ respectively according to the pumping and drainage plan by using the Fmincon function and Genetic Algorithm, and the single well pumping capacity and number of wells can also be optimized more reasonably. Therefore, it is feasible to use the objective function method to call the optimization toolbox to optimize the design of foundation pit dewatering and can achieve good optimization effect. [ABSTRACT FROM AUTHOR]

A large amount of rock dust is produced during the drilling, blasting, shoveling, and loading of the metal and non-metal underground mines and causes high dust concentration in the shaft space and endangers the health of,corkers and the working environment. Given that, in this paper, the tunneling roadway of a gold mine is taken as the research object, and the forced ventilation model of the tunneling roadway is established. According to the gas-solid two-phase flow theory combined with the field measurement data, the dust removal effect under different arrangement conditions of the air duct cloth is analyzed by using Fluent software, and the dust migration law and the wind speed distribution in the roadway are obtained. The research finds that the forced airflow of the fan forms a vortex near the lace that carries dust in a vortex around the face which is not conducive to the discharge of dust, and the airflow about 7 —8 m away from the face gradually flows to the return air lane; when the outlet of the air duct is 8 m away from the lace and the height is 1.5 m, the dust in the tunnel is discharged quickly and the dust removal effect is the most ideal. The research results have a certain guiding significance for the prevention and control of dust in the tunneling face. [ABSTRACT FROM AUTHOR]

The study heartbeat model based on Van der Pol equation is beneficial to heartbeat control and offering therapy guidance of cardiac diseaes such as arrhythmia. To cope with the issue that the timescale of the solutions produced by Van der Pol equation is different from those of real living beings, this paper introduced a timescale parameter into the Van der Pol equation. To solve the problem of numerical simulation of rhythm model, this paper proposed a deep neural network algorithm. To avoid spurious solutions caused by existing neural network algorithms, this paper proposed a new sampling strategy to construct training data sets. To further improve the accuracy, this paper introduced an adaptive sampling means into the proposed sampling strategy. This paper conducted numerical experiments and compared numerical solutions given by Runge-Kutta method with results of the proposed method. The results show that the maximum mean error of the proposed method is below 0. 3 %. Furthermore, this paper employed the deep neural network method to simulate the action potential of the cardiac pacemaker cell. The results show that the proposed method can simulate the action potential fairly well. [ABSTRACT FROM AUTHOR]

The electrode structure is an important factor of affecting the properties of atmospheric pressure plasma jets.The study on the plasma jets with different electrode structures is of great significance for optimizing jet devices and meeting different application requirements.Based on a two-dimensional fluid model, the propagation characteristics of the atmospheric-pressure He plasma jets were investigated numerically in this paper under the needle-ring-plate electrode structure, putting focus on investigating the effects of the voltage applied to the ring electrode and the position of the ring electrode on the jet behaviors.The results showed that, under the case when the ring electrode was grounded and under another case when the ring electrode and the needle electrode were connected to the same high voltage, the electron density for the former was higher than that for the latter, regardless of the position of the ring electrode.Also, the jet structure was not affected by the position of the ring electrode.However, the propagation speed and propagation distance of the jets were different under different positions of the ring electrode.When the ring electrode was far away from the nozzle, the jet with the grounded ring electrode propagated faster, and within the same time the obtained jet was longer.In contrast, if the ring electrode was closer to the nozzle, the jet traveled faster when a high voltage was applied to the ring electrode.The dominant physics associated with these observations were also analyzed and discussed in the paper. [ABSTRACT FROM AUTHOR]

In the process of landfill and operation, the shear strength of municipal landfill will change with the increase of age, and the stability of landfill itself will also change. In this paper, the analysis of shear strength parameters of garbage soil by domestic and foreign scholars was made, and the variation of cohesion and internal friction angle with age increasing was summarized. If the material of the landfill is similar, the cohesive force tends to decay with quadratic function while the internal friction angle increases with logarithmic function;moreover,after 10—15 years of landfill,the cohesion approached zero and the internal friction angle increases by 15°—25°．Then a layered landfill model was established,and the shear strength parameters related to age were given to each landfill layer.Finally,PLAXIS finite element software was used to analyze the slope stability of landfill at different ages.The stability safety factor decreases first and then increases with the age increase.The displacement is mainly concentrated in the middle of the slope while the settlement is mainly concentrated in the top of the slope.During the operation of landfill,attention should mainly be paid to the change of slope displacement and the safety of landfill around 10 years after sealing.The research results have obvious engineering significance for landfill design and site safely. [ABSTRACT FROM AUTHOR]

Hydrocyclone separation equipment is widely used in oil-water separation field because of its simple structure and high separation efficiency. In view of the smaller size and higher separation performance of cyclone separation equipment, the cyclone multi-pipe parallel connection is adopted in engineering. However, under the condition of large on-site processing capacity, unreasonable arrangement of the cyclone tube can lead to non-uniform distribution of flow and pressure drop among each single tube. That will cause shortages of independent swirl intensity, and ultimately affect the overall performance of cyclone separation system, making it difficult to achieve the desired effect. For in-depth understanding of the influence of different arrangement modes on flow field distribution features, the full-size flow field simulation is carried out by using computational fluid dynamics software, and the pressure and flow distribution characteristics of the multitube hydrocyclone separation system are analyzed. Results show that under the same processing, the arrangement of the multiple tube have effects on the flow distribution characteristics. In two kinds of arrangement, the uniform type and the triangle type, the flow in the cyclone tube away from the system entry is generally higher than that of the cyclone tube near the system entry. In the container of tank shell, the triangular arrangement designed in this paper is better than the uniform one in terms of even flow distribution and low energy consumption. Moreover, the triangular arrangement can effectively improve the utilization of space in the container. The research lays a foundation for independent research and development of efficient and compact hydrocyclone separation system. [ABSTRACT FROM AUTHOR]

The drainage channel and water-conductivity drillholes were proposed to carry out the seepage prevention for the grottoes to solve a series of geological hazards, such as water seepage at the top grottoes and bad stability of foundation. The 3D high simulation geological model was established by ANSYS-FLAC 3D software, and the drilling on bedding rock slope simulation model was simulated by interface and fill command of FLAC 3D software, respectively. The effects of different schemes on rock stress, displacement and plastic zone were analyzed to select the best anti-seepage scheme based on theoretical analysis and numerical simulation on the condition of original rock stress. The results show that the adding water-drilling has the least damage to the rock slope and meets the requirements for drainage of precipitate water and groundwater. The stability of rock slope is mainly affected by the diversion hole near the outside of the mountain, the depth of borehole is no obvious effect on the deformation. The comprehensive rock mass reinforcement and treatment technology combined with mountain spray anchor net support and low-pressure grouting can improve the stability of mountain slope. This paper provides an effective and economic method for the similar drainage and interception diversion of rock slopes, internal structures and rock slope reinforcement. [ABSTRACT FROM AUTHOR]

In this paper, the evolution of thermocapillary convection in melt of half-floating zone liquid bridge under the condition of zero gravity was studied by means of numerical simulation. Under the condition that the height L of the liquid bridge and the temperature difference ΔT remain unchanged, the aspect ratio (Ar = L / R) of the liquid bridge can be changed by changing the radius R of the liquid bridge. The convection in the liquid bridge exhibits various flow characteristics with the change of the aspect ratio Ar. Thermocapillary convection is in a three-dimensional steady state when Ar = 0. 5. The flow field and temperature field change from the steady state mode to the unsteady periodic multi-frequency oscillation mode satisfying the frequency doubling relationship (f n = nf 1) when Ar = 1. When Ar = 1. 25, the velocity oscillation frequency of the monitoring point increases, showing a smaller amplitude oscillation mode, and the temperature oscillation disappears. [ABSTRACT FROM AUTHOR]

Loess is a kind of Quaternary loose deposits. There are many primary and secondary pores and cracks in the loess, which provide preferential channels for water to enter the soil and form preferential infiltration phenomenon. This water movement mode is called preferential flow. The existence of preferential infiltration and preferential flow is one of the main causes of landslide and other loess geological disasters, so it is necessary to study the phenomenon of preferential infiltration. Based on the discussion of the classification of loess dominant structural planes by previous scholars, this paper puts forward the classification method of loess preferential channels, then discusses the preferential flow classification of domestic and foreign scholars and the main research methods, and analyzes their advantages and disadvantages. This paper summarizes the main infiltration models of the current preferential flow and the characteristics of the governing equations representing the models, analyzes and discusses the deficiency of present research and the development direction in the future at the end. [ABSTRACT FROM AUTHOR]

The study seeks to obtain the optimal strength requirement for the backfill body in downward small sublevel stope, and optimize the optimal strength for the backfill body in the process of mining while guaranteeing safe stoping conditions, so as to lower filing cost and realize the best economic benefits. The paper analyzes and calculates the strength requirements based on the mechanical parameters of the ore rock-backfill body in Karatunk Copper-Nickel Mine. Based on the suggested stope structure parameters(length, width, and height are 30 m, 8 m, and 12 m respectively), and the structural designs of the bottom layer, roof connection layer, and uncemented backfill body, the study uses Flac3D software to construct a 3D numerical model of ore rocks. The stability of backfill bodies with different strengths is studied when the roof is revealed downwards, to determine the numerical value of the minimum roof strength requirement of the backfill body in the process of downward mining, the difference and its causes of the backfill body strength calculation and numerical simulation results are comprehensively compared and analyzed, and the practical field situations are considered as well, before the downward backfill body strength and its structure design scheme are proposed, which realizes the coordination of stope structure parameters and backfill body parameters. [ABSTRACT FROM AUTHOR]

After a mine production transfers from the shallow part to the deep, the whole technical adjustment and optimization of the mine ventilation system are required. Given the poor effect of the ventilation system in an underground mine after its trial operation of the deep project, through investigation and detection of the current situation of the ventilation system, the paper figures out that there are the problems such as insufficient air volume, blocked air path, high resistance, insufficient capacity of the main fan, and the existence of air leakage, puts forward some debugging and optimization schemes, such as finding and sealing air leakage point, reducing the resistance of parallel return air circuit, optimizing type selection of the main fan, balancing return air circuit resistance of auxiliary fan. Modeling and calculation analysis are carried out using Ventsim software, verifying the feasibility of debugging scheme. The engineering application shows that it can meet the production demand of the deep underground mine ventilation. [ABSTRACT FROM AUTHOR]

The discovery of marginal ore body in Fankou lead-zinc mine makes the current filling system of the mine unable to meet the increasing demand of backfilling. According to the position of the newly proved ore bodies and the filling stations in Fankou, this paper puts forward two kinds of pipeline layout schemes: the construction of new filling boreholes and the use of original filling boreholes. The maximum allowable stowing gradients of graded tailings and fine tailings transported by ground filling pipeline are calculated to be 8. 56 and 3. 47. According to the theoretical calculation and numerical simulation results, it is considered that when the graded tailings and fine tailings are transported at the surface stage of filling pipeline, both schemes need to be transported by pumping. In the underground stage of filling pipeline, the graded tailings filling slurry can be transported by flow. When the filling times line drops below 3, fine tailings can be transported by flow. The calculation results of pumping pressure show that the filling system needs to be equipped with a filling pump with the maximum pumping capacity of not less than 12 MPa to meet the demand of filling slurry transportation in the mine. [ABSTRACT FROM AUTHOR]

In view of the problems of large temperature stratification and uneven cooling of grain piles in large warehouses, this paper is based on the theory of heat and mass transfer in porous media grain piles. This study incorporates methods from computational fluid dynamics coupled with the physics of heat transfer, fluid and moisture transport. A mathematical physical model for heat and moisture transfer in grain piles is established. The ventilation experiment of the one-story warehouse is simulated. The results from the experimental data and the results from the numerical simulations are compared. The temperature and moisture changes during actual ventilation and numerical simulation ventilation were explored. The results show that the model can predict the changes of airflow velocity, temperature and relative humidity inside the grain pile; when the initial average temperature of the grain pile is the same. When the inlet air temperature is increased from-17 ℃ to-4 ℃,the ventilation time is extended from 37 h to 108 h. When the speed is increased from 0.24 m/s to 0.31 m/s, the ventilation time is shortened from 228 h to 176 h. Changing the inlet air temperature or outlet wind speed will affect the required ventilation time. Economical ventilation time can be obtained by establishing the relationship between inlet air temperature and apparent wind speed, and outlet air speed and apparent wind speed. The fan with reasonable power can be selected based on this. Provide a reference for the ventilation operation of grain piles. [ABSTRACT FROM AUTHOR]

End face caving has always been a major technical problem affecting safe and efficient mining of working face. In this paper, the elastic foundation beam theory is used to establish the differential equation of the end face roof deflection, and the PHASE 2D finite element software is used to establish the numerical model of the end face roof stability, and the influence of coal seam depth, support stiffness, coal body stiffness and other factors on the stability of the backfill mining face end face roof. The results show that :(1) the larger the mining depth or the smaller the hydraulic support stiffness, the more obvious the end face roof subsidence; When the foundation coefficient or elastic modulus of coal seam roof increases, the subsidence of the end face roof decreases, but the influence is limited. Considering the feasibility, improving the stiffness of hydraulic support can effectively control the deformation of working face roof, and reduce the risk of end face roof falling and coal wall sheet wall. (2) When the buried depth of coal seam increases from 200 m to 250 m and 300 m, the plastic zone width and abutment pressure in front of the working face increase significantly, and the maximum subsidence of the direct roof is 61 mm, 78 mm and 96 mm, respectively. (3) When the elastic modulus of coal seam increases from 2 500 MPa to 3 500 MPa and 4 500 MPa, the peak value of abutment pressure in front of working face increases slightly, and so does the width of coal plastic zone in front of working face. The amount of direct roof subsidence decreases slightly. (4) The field observation shows that the support resistance is small under the backfill mining condition, the ore pressure in the working face area is not obvious, and the roof subsidence is effectively controlled. [ABSTRACT FROM AUTHOR]

Objective The oil - increasing effect of in-situ carbon dioxide foam was gradually weakened in multicycle profile control. It was urgent to analyze the decreasing law of the system. Methods The paper studied the law of in-situ carbon dioxide foam profile control with multiple rounds by using large scale visual plate physical model and numerical simulation model which combined with the characteristics of vertical heterogeneity in Bohai oil field reservoir. And an attempt was made to extend the reaction time of the system to increase its action distance. Results The research showed that water flooding could only sweep the high permeability layer in the lower part of the reservoir, but it could not sweep the low permeability layer in t he upper part. The in-situ carbon dioxide foam profile control system could entered the high permeability layer to form plugging and started the low permeability layer, which improved oil recovery more than 10 % in t he first cycle of profile control. But the system could not enter the deeper location with the profile control rounds increased. The enhanced oil recovery value constantly decreased, which was less than 1% by the fourth cycle of profile control. The remaining oil of the high permeability layer was mainly distributed in the two wings and the remaining oil of the low permeability layer was evenly distributed. Conclusions The effective distance of in-situ carbon dioxide foam system was short which was failed to work in deeper reservoir with the profile control rounds increased. T he effect of multicycle profile control was better by prolonging the reaction time to increase its effective distance, which increased the total enhanced oil recovery value by :3. 66%. [ABSTRACT FROM AUTHOR]