scholarly journals Re-crushing process and non-Darcian seepage characteristics of broken coal medium in coal mine water inrush

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mingkun Pang ◽  
Tianjun Zhang ◽  
Yi Guo ◽  
Lei Zhang
Keyword(s):  
Flow Rate ◽  
Mine Water ◽  
Early Stage ◽  
Flow Behavior ◽  
Water Inrush ◽  
Sudden Change ◽  
Seepage Characteristics ◽  
Seepage Factor ◽  
Dependence Relationship ◽  
Infiltration Method

AbstractThe initiation process of the mine water inrush accident, the essence of this process is the sudden change of the seepage state of the broken coal medium under pressure and the instability of the skeleton. In order to study the re-crushing mechanism and seepage characteristics of the broken coal medium under load, a set of three-axis seepage system was designed independently. Using the steady-state infiltration method, multiple flow factors under different particle size combinations and different stress conditions of the broken coal medium were obtained. The results of the study indicate: in one hand, the reduction of the porosity of the broken coal medium will cause the flow channel to be rebuilt, and the sudden change of flow rate will directly lead to the non-Darcian flow behavior. The early stage of compaction mainly affects the permeability k value, and the later stage of compaction mainly affects the non-Darcian β value; On the other hand, the seepage throat in the broken coal medium may have a sharp increase in its flow rate, leading to a sudden change in the flow pattern. The critical Reynolds number is also used to determine whether non-Darcian flow is formed, and its value in the water inrush system is about 40–133; at the same time, the non-Darcian flow in the broken coal medium conforms to the Forchheimer-type flow law. By analyzing the dependence relationship between factors, a seepage factor representation algebraic relationship suitable for Forchheimer type non-Darcian flow of broken coal medium is given, which can be used as a calculation basis in the prevention and treatment of mine water inrush accidents.

A modern method of treating initial caries for children using the infltration method

2020 ◽  
Vol 20 (1) ◽  
pp. 4-8
Author(s):  
A. U. Zamurayeva ◽  
Е. T. Supiyeva ◽  
B Sh. Orynbayeva
Keyword(s):  
Pathogenic Bacteria ◽  
Early Stage ◽  
Modern Method ◽  
Modern Technology ◽  
White Spot ◽  
Tooth Decay ◽  
Low Viscosity ◽  
Initial Caries ◽  
Short Time ◽  
Infiltration Method

Relevance. The modern method of infiltration provides an opportunity to stop the spread of pathogenic bacteria and the development of caries at the white spot stage, replacing the destroyed enamel cells with special polymers having low viscosity and high penetrating ability. The stabilization of the process is achieved in a short time with the maximum safety of their tissues. Purpose. Treatment of initial tooth decay in children by infiltration, assessment of the effectiveness and advantages of modern technology. Materials and methods. Clinical examination was carried out according to generally accepted methods. Additionally, a laser diagnostic method was used using the KaVo DIAGNOdent device (Germany). The LLP Dentistry Center «Zhaik Dent» and the LLP «Concept» used the Icon system for the treatment of initial caries and after orthodontic treatment for 25 children with 54 teeth. Results. At the end of tooth treatment with the Icon infiltration method, parents and the child were given recommendations: from the next day, brush your teeth 2 times a day, rinse your mouth regularly after eating, do not drink drinks, products with coloring substances. To monitor the result of treatment, the child was prescribed for reexamination after 7-10 days, after one month, in the following periods – once a year.After working with the material of the Icon system, the authors noted the pronounced effects of the treatment of initial caries by the method of infiltration.Conclusions. 1. The method of infiltration is a modern and promising technology for the treatment of dental caries at an early stage without losing healthy tissues. 2. The Icon infiltration method makes it possible to stop the spread of pathogenic bacteria and develop tooth decay at the white spot stage, replacing the destroyed enamel cells with special polymers having low viscosity and high penetrating ability. 3. The stabilization of the carious process is achieved in a short time with the maximum preservation of the tooth's tissues. 

Groundwater flow simulation and its application in GaoSong ore field, China

2018 ◽  
Vol 10 (2) ◽  
pp. 276-284 ◽  
Author(s):  
Gang Chen ◽  
Shiguang Xu ◽  
Chunxue Liu ◽  
Lei Lu ◽  
Liang Guo
Keyword(s):  
Numerical Model ◽  
Flow Field ◽  
Groundwater Flow ◽  
Mine Water ◽  
Permeability Coefficient ◽  
Water Inrush ◽  
Seepage Field ◽  
Groundwater Seepage ◽  
Calculation Results ◽  
Groundwater Flow Field

Abstract Mine water inrush is one of the important factors threatening safe production in mines. The accurate understanding of the mine groundwater flow field can effectively reduce the hazards of mine water inrush. Numerical simulation is an important method to study the groundwater flow field. This paper numerically simulates the groundwater seepage field in the GaoSong ore field. In order to ensure the accuracy of the numerical model, the research team completed 3,724 field fissure measurements in the study area. The fracture measurement results were analyzed using the GEOFRAC method and the whole-area fracture network data were generated. On this basis, the rock mass permeability coefficient tensor of the aquifer in the study area was calculated. The tensor calculation results are used in the numerical model of groundwater flow. After calculation, the obtained numerical model can better represent the groundwater seepage field in the study area. In addition, we designed three different numerical models for calculation, mainly to explore the influence of the tensor assignment of permeability coefficient on the calculation results of water yield of the mine. The results showed that irrational fathom tensor assignment would cause a significant deviation in calculation results.

Effect of Surface State of Die on Flow Rate of Steamed Bamboo Powder in Thermal Flow Test Using Capillary Rheometer

2015 ◽  
Vol 651-653 ◽  
pp. 830-835
Author(s):  
Shohei Kajikawa ◽  
Riku Sakagami ◽  
Takashi Iizuka
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Surface State ◽  
Flow Behavior ◽  
Thermal Flow ◽  
Average Roughness ◽  
Arithmetic Average ◽  
Flow Test ◽  
Die Surface ◽  
Bamboo Powder

Thermal flow tests were performed on steamed bamboo powder using capillaries that were processed under different conditions in order to investigate the effect of the die surface state on the fluidity of the woody powder. The capillaries were processed by wire-cut electric discharge machining, reaming or drilling, and the arithmetic average roughness (Ra) varied from 0.5 to 2.5 μm. The bamboo powder was first steamed at 200 °C for 20 min, and its particle size was then controlled using different mesh screens. The thermal flow temperature was set at 200 °C. The results indicated that the flow behavior improved with increasing particle size. For the capillaries processed by WEDM, the flow rate for samples with particle sizes of 75~150 and 150~300 μm decreased with increasing Ra. On the other hand, when reaming or drilling was used to process the capillaries, the flow rate was almost independent of Ra, regardless of the particle size.

LIPOID NEPHROSIS

PEDIATRICS ◽  
1948 ◽  
Vol 1 (6) ◽  
pp. 733-753
Author(s):  
WALTER M. BLOCK ◽  
ROBERT L. JACKSON ◽  
GENEVIEVE STEARNS ◽  
MIRIAM P. BUTSCH
Keyword(s):  
Early Diagnosis ◽  
Normal Values ◽  
Early Stage ◽  
Sudden Change ◽  
Cholesterol Esters ◽  
Erythrocyte Sedimentation ◽  
Biochemical Studies ◽  
Prolonged Duration ◽  
Cholesterol Fraction ◽  
Active Disease

Clinical and biochemical studies of 40 children with lipoid nephrosis are evaluated. Twenty-six (65 %) are alive; 19 have been entirely well for 1 to 16 years, including three who had minimal hematuria on various occasions. Three have been well for less than a year, one still has proteinuria only, and three still have active disease. Of 22 children who had received sulfonamides for infections, only three have died. Necropsy was done on 10 of the 14 children who died. Minor glomerular changes were seen in the kidneys of four children not known to have had hematuria. Pronounced glomerular changes occurred in two children who had minimal hematuria. Of the four children who did not show any glomerular changes, two had minimal hematuria on several occasions. Pathologic changes in the liver were minimal unless acacia had been given. Laboratory determinations revealed no significant alteration of the prothrombin time. Most of the increase in the plasma fats was in the cholesterol fraction. The precentage of cholesterol esters was not decreased. In case of recovery, the cholesterol seemed to return to normal values at a slower rate than the serum albumin. Plasma fat reached values exceeding 5 gm./100 ml. in some instances. No "critical edema level" for albumin was found. The erythrocyte sedimentation test was a reliable guide in determining the course of the disease. Choline citrate (0.8 gm. each day), given to seven children for prolonged periods, failed to produce essential changes in the plasma fats or definite clinical improvement. Periods of sudden change in edema were found to be critical times for the nephrotic child. Two children developed cardiac failure after injection of large volumes of sucrose. Early diagnosis is important, for treatment is most effective in the early stage. The prognosis is good since the advent of chemo- and antibiotic therapy, and is not impaired by prolonged duration of the disease. Growth of the children who recover is good.

Effect of Outer Fin Axial Gap on the Sealing Effectiveness and Fluid Dynamics of Radial Rim Seal

2017 ◽  
Author(s):  
Zhigang Li ◽  
Jun Li ◽  
Liming Song ◽  
Qing Gao ◽  
Xin Yan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Flow Rate ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Navier Stokes ◽  
Hot Gas

The modern gas turbine is widely applied in the aviation propulsion and power generation. The rim seal is usually designed at the periphery of the wheel-space and prevented the hot gas ingestion in modern gas turbines. The high sealing effectiveness of rim seal can improve the aerodynamic performance of gas turbines and avoid of the disc overheating. Effect of outer fin axial gap of radial rim seal on the sealing effectiveness and fluid dynamics was numerically investigated in this work. The sealing effectiveness and fluid dynamics of radial rim seal with three different outer fin axial gaps was conducted at different coolant flow rates using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and SST turbulent model solutions. The accuracy of the presented numerical approach for the prediction of the sealing performance of the turbine rim seal was demonstrated. The obtained results show that the sealing effectiveness of radial rim seal increases with increase of coolant flow rate at the fixed axial outer fin gap. The sealing effectiveness increases with decrease of the axial outer fin gap at the fixed coolant flow rate. Furthermore, at the fixed coolant flow rate, the hot gas ingestion increases with the increase of the axial outer fin gap. This flow behavior intensifies the interaction between the hot gas and coolant flow at the clearance of radial rim seal. The preswirl coefficient in the wheel-space cavity is also illustrated to analyze the flow dynamics of radial rim seal at different axial outer fin gaps.

scholarly journals Effect of the Flame Dome Depth and Improvement of the Pressure Loss in the Dump Diffuser

1998 ◽  
Author(s):  
Shinji Honami ◽  
Wataru Tsuboi ◽  
Takaaki Shizawa
Keyword(s):  
Velocity Profile ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Pressure Loss ◽  
Total Pressure ◽  
Flow Behavior ◽  
Sudden Expansion ◽  
Mean Velocity ◽  
The Mean ◽  
Stress Profiles

This paper presents the effect of flame dome depth on the total pressure performance and flow behavior in a sudden expansion region of the combustor diffuser without flow entering the dome head. The mean velocity and turbulent Reynolds stress profiles in the sudden expansion region were measured by a Laser Doppler Velocitmetry (LDV) system. The experiments show that total pressure loss is increased, when flame dome depth is increased. Installation of an inclined combuster wall in the sudden expansion region is suggested from the viewpoint of a control of the reattaching flow. The inclined combustor wall is found to be effective in improvement of the diffuser performance. Better characteristics of the flow rate distribution into the branched channels are obtained in the inclined wall configuration, even if the distorted velocity profile is provided at the diffuser inlet.

scholarly journals Description of Fracture Network of Hydraulic Fracturing Vertical Wells in Unconventional Reservoirs

2021 ◽  
Vol 9 ◽  
Author(s):  
Jinghua Liu ◽  
Mingjing Lu ◽  
Guanglong Sheng
Keyword(s):  
Flow Rate ◽  
Early Stage ◽  
Fractal Theory ◽  
Fracture Network ◽  
Unconventional Reservoirs ◽  
Box Dimension ◽  
Vertical Wells ◽  
Reservoir Permeability ◽  
Fractal Index ◽  
Volume Fracturing

Based on the distribution of complex fractures after volume fracturing in unconventional reservoirs, the fractal theory is used to describe the distribution of volume fracture network in unconventional reservoirs. The method for calculating the fractal parameters of the fracture network is given. The box dimension method is used to analyze a fracturing core, and the fractal dimension is calculated. The fractal index of fracture network in fracturing vertical wells are also firstly calculated by introducing an analysis method. On this basis, the conventional dual-media model and the fractal dual-media model are compared, and the distribution of reservoir permeability and porosity are analyzed. The results show that the fractal porosity/permeability can be used to describe the reservoir physical properties more accurately. At the same time, the flow rate calculating by conventional dual-media model and the fractal dual-media model were calculated and compared. The comparative analysis found that the flow rate calculated by the conventional dual-media model was relatively high in the early stage, but the flow rate was not much different in the later stage. The research results provide certain guiding significance for the description of fracture network of volume fracturing vertical well in unconventional reservoirs.

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