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Influence of confined water on the limit support pressure of tunnel face in weakly water-rich strata
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作者 LI Yun-fa WU Guo-jun +2 位作者 CHEN Wei-zhong YUAN Jing-qiang HUO Meng-zhe 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第8期2844-2859,共16页
In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confine... In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confined water on the limit support pressure of the tunnel face.This study employed the finite element method(FEM)to analyze the limit support pressure of shield tunnel face instability within a pressurized water-containing layer.Subsequently,a multiple linear regression approach was applied to derive a concise solution formula for the limit support pressure,incorporating various influencing factors.The analysis yields the following conclusions:1)The influence of confined water on the instability mode of the tunnel face in soft soil layers makes the displacement response of the strata not significant when the face is unstable;2)The limit support pressure increases approximately linearly with the pressure head,shield tunnel diameter,and tunnel burial depth.And inversely proportional to the thickness of the impermeable layer,soil cohesion and internal friction angle;3)Through an engineering case study analysis,the results align well with those obtained from traditional theoretical methods,thereby validating the rationality of the equations proposed in this paper.Furthermore,the proposed equations overcome the limitation of traditional theoretical approaches considering the influence of changes in impermeable layer thickness.It can accurately depict the dynamic variation in the required limit support pressure to maintain the stability of the tunnel face during shield tunneling,thus better reflecting engineering reality. 展开更多
关键词 weakly water-rich strata confined aquifer limit support pressure finite element method multiple linear regression
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Synthetic analysis of meteorological elements for the sea fogs occurred in northwest the Yellow Sea under low pressure control and comparison with sea fogs occurred under high pressure control in summer
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作者 WANG Kaiyue MA Zheng +3 位作者 MIAO Qingsheng ZHAO Binru ZHANG Zengjian LI Cheng 《Marine Science Bulletin》 2024年第1期1-18,共18页
Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation si... Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation situation,divergence and vertical velocity field,and the vertical profile of temperature and humidity are synthesized and analyzed.The basic characteristics of the circulation and physical field of sea fog under low pressure control(L type sea fog)are obtained,and the results are compared with the sea fog under the control of high pressure(H type sea fog):a)L type sea fogs potential height anomaly disturbance is mainly manifested in the low layer,and its average value is-65.66 gpm,gradually weakening upward;b)L type sea fogs inversion structure is weaker than H type sea fogs when it occurs,the fog layer is thicker and the high relative humidity level is high over the fog layer,while the H type sea fogs fog layer has a relatively obvious dry layer;c)L sea fog has three layers of structure at the vertical direction.The first layer 1000-950 hPa is convergence accompanied by weak rise and subsidence,the second layer 950-850 hPa is divergence accompanied by weak subsidence,and the third layer 850 to 500hPa is gradually strengthened.While there are two layer structures of the H type sea fog.1000 hPa is divergence accompanied by weak rising and sinking movement,950-500 hPa is a uniform subsidence movement.d)Probability density statistical analysis further quantified the vertical movement of L and H type sea fog and the distribution of relative humidity in each layer.These conclusions provide an important reference for forecasting the sea fog in the northwest of the Yellow Sea under the condition of low pressure circulation in summer. 展开更多
关键词 sea fog under the low pressure control sea fog under the high pressure control northwest of the Yellow Sea synthetic analysis transient method
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CALCULATION METHOD FOR EARTH PRESSURE CONSIDERING DISPLACEMENT 被引量:1
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作者 张小平 胡明亮 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2009年第3期229-234,共6页
The calculation of earth pressure is a difficult problem in the pit foundation design. Aiming at the problem, the earth pressure calculation formulas considering the displacement are proposed. A method for determining... The calculation of earth pressure is a difficult problem in the pit foundation design. Aiming at the problem, the earth pressure calculation formulas considering the displacement are proposed. A method for determining the limit displacement is given and it is convenient for use. The result indicates that the earth pressure calculated by the formulas is between the earth pressure at rest and the Rankine earth pressure, the formulas can reflect the change rules of active and passive earth pressures along with the displacement. Moreover, the calculation result using the formulas is approximate to the monitoring result. It confirms the validity of the formula deduction and the rationality of the calculation results. As for the passive earth pressure, the calculation method is theoretically feasible. 展开更多
关键词 FOUNDATIONS finite element method DISPLACEMENT earth pressure
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Various admixtures to mitigate the long-term strength retrogression of Portland cement cured under high pressure and high temperature conditions 被引量:2
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作者 Jiankun Qin Xueyu Pang +2 位作者 Ashok Santra Guodong Cheng Hailong Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第1期191-203,共13页
In order to investigate the problem of long-term strength retrogression in oil well cement systems exposed to high pressure and high temperature(HPHT)curing conditions,various influencing factors,including cement sour... In order to investigate the problem of long-term strength retrogression in oil well cement systems exposed to high pressure and high temperature(HPHT)curing conditions,various influencing factors,including cement sources,particle sizes of silica flour,and additions of silica fume,alumina,colloidal iron oxide and nano-graphene,were investigated.To simulate the environment of cementing geothermal wells and deep wells,cement slurries were directly cured at 50 MPa and 200?C.Mineral compositions(as determined by X-ray diffraction Rietveld refinement),water permeability,compressive strength and Young’s modulus were used to evaluate the qualities of the set cement.Short-term curing(2e30 d)test results indicated that the adoption of 6 m m ultrafine crystalline silica played the most important role in stabilizing the mechanical properties of oil well cement systems,while the addition of silica fume had a detrimental effect on strength stability.Long-term curing(2e180 d)test results indicated that nano-graphene could stabilize the Young’s modulus of oil well cement systems.However,none of the ad-mixtures studied here can completely prevent the strength retrogression phenomenon due to their inability to stop the conversion of amorphous to crystalline phases. 展开更多
关键词 High pressure and high temperature(HPHT) Strength retrogression Young’s modulus Water permeability Rietveld method
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Improved finite difference method for pressure distribution of aerostatic bearing 被引量:4
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作者 郑书飞 蒋书运 《Journal of Southeast University(English Edition)》 EI CAS 2009年第4期501-505,共5页
An improved finite difference method (FDM)is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aero... An improved finite difference method (FDM)is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aerostatic bearings. A detailed theoretical analysis of the pressure distribution of the orifice-compensated aerostatic journal bearing is presented. The nonlinear dimensionless Reynolds equation of the aerostatic journal bearing is solved by the finite difference method. Based on the principle of flow equilibrium, a new iterative algorithm named the variable step size successive approximation method is presented to adjust the pressure at the orifice in the iterative process and enhance the efficiency and convergence performance of the algorithm. A general program is developed to analyze the pressure distribution of the aerostatic journal bearing by Matlab tool. The results show that the improved finite difference method is highly effective, reliable, stable, and convergent. Even when very thin gas film thicknesses (less than 2 Win)are considered, the improved calculation method still yields a result and converges fast. 展开更多
关键词 aerostatic bearing: pressure distribution: Reynolds equation: finite difference method variable step size
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A Generalized Limit Equilibrium Method for the Solution of Active Earth Pressure on a Retaining Wall 被引量:11
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作者 OUYANG Chao-jun XU Qiang +2 位作者 HE Si-ming LUO Yu WU Yong 《Journal of Mountain Science》 SCIE CSCD 2013年第6期1018-1027,共10页
In this paper, a generalized limit equilibrium method of solving the active earth pressure problem behind a retaining wall is proposed.Differing from other limit equilibrium methods, an arbitrary slip surface shape wi... In this paper, a generalized limit equilibrium method of solving the active earth pressure problem behind a retaining wall is proposed.Differing from other limit equilibrium methods, an arbitrary slip surface shape without any assumptions of pre-defined shapes is needed in the current framework, which is verified to find the most probable failure slip surface. Based on the current computational framework, numerical comparisons with experiment, discrete element method and other methods are carried out. In addition, the influences of the inclination of the wall, the soil cohesion, the angle of the internal friction of the soil, the slope inclination of the backfill soil on the critical pressure coefficient of the soil, the point of application of the resultant earth pressure and the shape of the slip surface are also carefully investigated. The results demonstrate that limit equilibrium solution from predefined slip plane assumption, including Coulomb solution, is a special case of current computational framework. It is well illustrated that the current method is feasible to evaluate the characteristics of earth pressure problem. 展开更多
关键词 Limit equilibrium method Retainingwall Active earth pressure Critical slip surface
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High-pressure phonon dispersion of copper by using the modified analytic embedded atom method 被引量:2
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作者 张晓军 陈长乐 凤飞龙 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第9期520-524,共5页
By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three hig... By using the Born-von Kfirmfin theory of lattice dynamics and the modified analytic embedded atom method, we reproduce the experimental results of the phonon dispersion in fcc metal Cu at zero pressure along three high symmetry directions and four oft-symmetry directions, and then simulate the phonon dispersion curves of Cu at high pressures of 50, 100, and 150 GPa. The results show that the shapes of dispersion curves at high pressures are very similar to that at zero pressure. All the vibration frequencies of Cu in all vibration branches at high pressures are larger than the results at zero pressure, and increase correspondingly as pressure reaches 50, 100, and 150 GPa sequentially. Moreover, on the basis of phonon dispersion, we calculate the values of specific heat of Cu at different pressures. The prediction of thermodynamic quantities lays a significant foundation for guiding and judging experiments of thermodynamic properties of solids under high pressures. 展开更多
关键词 phonon dispersion high pressure SIMULATION modified analytic embedded atom method
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The pressure field in the liquid column in the tube-arrest method 被引量:2
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作者 应崇福 李超 +1 位作者 徐德龙 邓京军 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第7期2580-2589,共10页
We have been using the method of tube-arrest as a means of producing transient single cavitation bubble. In the present paper we seek to comprehend the mechanism of production and inquire into the structure of the ab ... We have been using the method of tube-arrest as a means of producing transient single cavitation bubble. In the present paper we seek to comprehend the mechanism of production and inquire into the structure of the ab initio pressure field in the arrested liquid column. The generated pressure wave is shown by combining the theoretical analysis with the experimental observation to be a slightly varied version of water hammer. With relatively clean liquid, the magnitude of the tension peak generating the TSB is likely to reach of several millions Pa. It is also shown that the so generated cavitation bubble originating from the gas-containing bulk liquid is in ‘violent’ motion. 展开更多
关键词 tube-arrest method original pressure wave water hammer origin of violent cavitation bubble
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Dynamic ModeⅡfracture behavior of rocks under hydrostatic pressure using the short core in compression(SCC)method 被引量:6
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作者 Wei Yao Ying XuChonglang Wang +1 位作者 Kaiwen Xia Mikko Hokka 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2021年第5期927-937,共11页
The shear failure of rocks under both a static triaxial stress and a dynamic disturbance is common in deep underground engineering and it is therefore essential for the design of underground engineering to quantitivel... The shear failure of rocks under both a static triaxial stress and a dynamic disturbance is common in deep underground engineering and it is therefore essential for the design of underground engineering to quantitively estimate the dynamic ModeⅡfracture toughness KⅡCof rocks under a triaxial stress state.However,the method for determining the dynamic KⅡCof rocks under a triaxial stress has not been developed yet.With an optimal sample preparation,the short core in compression(SCC)method was designed and verified in this study to measure the dynamic KⅡCof Fangshan marble(FM)subjected to different hydrostatic pressures through a triaxial dynamic testing system.The formula for calculating the dynamic KⅡCof the rock SCC specimen under hydrostatic pressures was obtained by using the finite element method in combination with secondary cracks.The experimental results indicate that the failure mode of the rock SCC specimen under a hydrostatic pressure is the shear fracture and the KⅡCof FM increases as the loading rate.In addition,at a given loading rate the dynamic rock KⅡCis barely affected by hydrostatic pressures.Another important observation is that the dynamic fracture energy of FM enhances with loading rates and hydrostatic pressures. 展开更多
关键词 Loading rate Finite element method ModeⅡfracture toughness Fangshan marble Hydrostatic pressure Short core in compression
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A fast explicit finite difference method for determination of wellhead injection pressure 被引量:2
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作者 白冰 李小春 +2 位作者 刘明泽 石露 李琦 《Journal of Central South University》 SCIE EI CAS 2012年第11期3266-3272,共7页
A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditiona... A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditional numerical method of the same equations corroborates well the reliability and rate of FEFDM.Moreover,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of FEFDM.At last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead pressure.The result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be deleted.It is also shown that with flow rate increasing,the friction term can no longer be neglected. 展开更多
关键词 wellhead pressure injection pressure bottom-hole pressure fast explicit finite difference method
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Natural frequency characteristics of thin-walled homogeneous and manifold layered cylindrical shells under pressure using energy method 被引量:2
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作者 M.R.Isvandzibaei Hishamuddin Jamaluddin Raja Ishak Raja Hamzah 《Journal of Central South University》 SCIE EI CAS 2014年第2期521-532,共12页
Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The st... Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The study is carried out based on strain-displacement relationship from Love's shell theory with beam functions as axial modal function.A manifold layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum.The homogeneous cylindrical shell is made-up of isotropic one layer with stainless steel.The governing equations with uniform external lateral pressure for homogeneous isotropic and manifold layered isotropic cylindrical shells are obtained using energy functional by the Lagrangian function with Rayleigh-Ritz method.The boundary conditions that are presented at the end conditions of the cylindrical shell are simply supported-simply supported,clamped-clamped and free-free.The influences of uniform external lateral pressure and symmetrical boundary conditions on the natural frequency characteristics for both homogeneous and manifold layered isotropic cylindrical shells are examined.For all boundary conditions considered,the natural frequency of both cylindrical shells with symmetric uniform lateral pressure increases as h/R ratio increases and those considering natural frequency of the both cylindrical shells with symmetric uniform lateral pressure decrease as L/R ratio increases. 展开更多
关键词 cylindrical shell manifold layered pressure energy method
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Preparation and Characterization of Phenolic Prepolymer Impregnated Chinese Fir by Cyclic Increasing-Pressure Method with Green and Efficient 被引量:3
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作者 Yuan Zhang Ping Li +3 位作者 Yiqiang Wu Guangming Yuan Xianjun Li Yingfeng Zuo 《Journal of Renewable Materials》 SCIE EI 2020年第11期1473-1488,共16页
The Chinese fir wood was impregnated using a cyclic increasingpressure method(CIPM)with phenolic prepolymers as the impregnating modifier.Unmodified Chinese fir and progressive increasing-pressure method(PIPM)impregn... The Chinese fir wood was impregnated using a cyclic increasingpressure method(CIPM)with phenolic prepolymers as the impregnating modifier.Unmodified Chinese fir and progressive increasing-pressure method(PIPM)impregnated Chinese fir were used as reference samples and were compared and analyzed.The product’s chemical structure,internal morphology,crystal structure,and heat resistance were characterized.The transversal and longitudinal sections showed better filling effects,so that it bore greater external loading and reduced the water storage space.CIPM infused more phenolic prepolymer into the Chinese fir.Not only producing more physical filling but also forming more hydrogen bond associations and chemical bond combinations.Compared with PIPM and unmodi-fied Chinese fir,the CIPM impregnated Chinese fir had better mechanical strength and water resistance.The cellulose chains in CIPM impregnated Chinese fir were more closely linked and their crystallinity were clearly improved.Changes in internal morphology and crystal structure explained the reason why the mechanical properties and water resistance of CIPM impregnated Chinese fir were improved significantly.This Chinese fir had lower thermal decomposition rates,higher decomposition residual rates,and smaller combustion flames,which confirmed that it possessed improved heat and fire resistance. 展开更多
关键词 Chinese fir phenolic prepolymer cyclic increasing pressure method chemical structure crystalline structure heat resistance
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A modified logarithmic spiral method for determining passive earth pressure 被引量:1
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作者 Shiyi Liu Yang Xia Li Liang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第6期1171-1182,共12页
In this study, a modified logarithmic spiral method is proposed to determine the passive earth pressure and failure surface of cohesionless sloping backfill, with presence of wallesoil interface friction. The proposed... In this study, a modified logarithmic spiral method is proposed to determine the passive earth pressure and failure surface of cohesionless sloping backfill, with presence of wallesoil interface friction. The proposed method is based on a limit equilibrium analysis wherein the assumed profile of the backfill failure surface is a composite of logarithmic spiral and its tangent. If the wallesoil interface is smooth, a straight line does not need to be assumed for the failure surface. The geometry of the failure surface is determined using the Mohr circle analysis of the soil. The resultant passive earth thrust is computed considering equilibrium of moments. The passive earth pressure coefficients are calculated with varied values of soil internal friction angle and cohesion, wall friction angle and inclination angle, and sloping backfill angle. This method is verified with the finite element method(FEM) by comparing the horizontal passive earth pressure and failure surface. The results agree well with other solutions, particularly with those obtained by the FEM. The implementation of the present method is efficient. The logarithmic spiral theory is rigorous and self-explanatory for the geotechnical engineer. 展开更多
关键词 Passive earth pressure Logarithmic spiral method Finite element method(FEM) Sloping backfill Retaining wall
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Effect of overburden pressure on determination of reservoir rock types using RQI/FZI,FZI^* and Winland methods in carbonate rocks 被引量:2
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作者 Aboozar Soleymanzadeh Saeed Parvin Shahin Kord 《Petroleum Science》 SCIE CAS CSCD 2019年第6期1403-1416,共14页
Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distin... Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions. 展开更多
关键词 Overburden pressure Carbonate rocks Rock type Reservoir quality index Flow zone indicator Winland method
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Synthesis of large diamond crystals containing high-nitrogen concentration at high pressure and high temperature using Ni-based solvent by temperature gradient method 被引量:1
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作者 黄国锋 贾晓鹏 +4 位作者 李尚升 张亚飞 李勇 赵明 马红安 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第11期662-666,共5页
This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure ... This paper reprots that with Ni-based catalyst/solvent and with a dopant of NAN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus (SPD-6 × 1200), and the highest nitrogen concentration reaches approximately 121-1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 CPa and 1240-1300 ℃. The growth behaviour of diamond with high-nitrogen concentration is investigated in detail. The results show that, with increasing the content of NaN3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases. 展开更多
关键词 high temperature and high pressure nitrogen-doped diamond crystal temperature gra- dient method additive NaN3
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Optimization of the Algorithm for Increasing Injection Rate in Water Injection Wells for Pressure Optimization in P Oilfield
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作者 Lingyu Li 《World Journal of Engineering and Technology》 2023年第2期246-251,共6页
In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy sec... In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy security. In order to improve the quality of water injection in the oilfield and gradually achieve efficient and stable production, Bohai Oilfield has launched a water injection well pressure optimization project, focusing on improving the efficiency and quality of water injection in the water injection wells, in order to achieve the optimal water injection plan. In practical work, P Oilfield continues to promote the development of water injection well pressure optimization projects, emphasizing practical exploration and continuous optimization of work plans. However, during the project implementation process, there were some problems, one of which was that the statistics of cumulative injection volume were not scientific enough, resulting in a more comprehensive and accurate presentation of the actual results of pressure optimization work. In the context of continuous improvement work, after careful analysis and research, P Oilfield has decided to optimize the cumulative injection rate algorithm to guide the oilfield’s water injection work in a more refined way, ensuring sufficient and good water injection, and enhancing the oilfield’s production efficiency and comprehensive competitiveness. 展开更多
关键词 Offshore Oil Fields Water Injection Wells pressure Optimization Water Injection Volume Calculation method
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An improved outer pipe method for expansive pressure measurement of static cracking agents 被引量:1
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作者 Shuai Xu Pengyuan Hou +1 位作者 Runran Li Fidelis T.Suorineni 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第1期27-39,共13页
Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gase... Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gases encountered in explosive blasting processes.Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application.An improved outer pipe method(OPM),termed the upper end surface method(UESM),is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs.Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment.The new equipment is calibrated using oil pressure and strain measurements.The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential.The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%.The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs. 展开更多
关键词 Static cracking agent Hydration reaction Expansive pressure measurement Outer pipe method Upper end surface method Numerical simulation
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Data-driven Methods to Predict the Burst Strength of Corroded Line Pipelines Subjected to Internal Pressure 被引量:1
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作者 Jie Cai Xiaoli Jiang +2 位作者 Yazhou Yang Gabriel Lodewijks Minchang Wang 《Journal of Marine Science and Application》 CSCD 2022年第2期115-132,共18页
A corrosion defect is recognized as one of the most severe phenomena for high-pressure pipelines,especially those served for a long time.Finite-element method and empirical formulas are thereby used for the strength p... A corrosion defect is recognized as one of the most severe phenomena for high-pressure pipelines,especially those served for a long time.Finite-element method and empirical formulas are thereby used for the strength prediction of such pipes with corrosion.However,it is time-consuming for finite-element method and there is a limited application range by using empirical formulas.In order to improve the prediction of strength,this paper investigates the burst pressure of line pipelines with a single corrosion defect subjected to internal pressure based on data-driven methods.Three supervised ML(machine learning)algorithms,including the ANN(artificial neural network),the SVM(support vector machine)and the LR(linear regression),are deployed to train models based on experimental data.Data analysis is first conducted to determine proper pipe features for training.Hyperparameter tuning to control the learning process is then performed to fit the best strength models for corroded pipelines.Among all the proposed data-driven models,the ANN model with three neural layers has the highest training accuracy,but also presents the largest variance.The SVM model provides both high training accuracy and high validation accuracy.The LR model has the best performance in terms of generalization ability.These models can be served as surrogate models by transfer learning with new coming data in future research,facilitating a sustainable and intelligent decision-making of corroded pipelines. 展开更多
关键词 Pipelines CORROSION Burst strength Internal pressure Data-driven method Machine learning
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Diffusion-controlled Adsorption Kinetics at Air/Solution Surface Studied by Maximum Bubble Pressure Method 被引量:1
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作者 刘俊吉 王创业 MESSOW Ulf 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2004年第4期577-581,共5页
In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be... In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be used. In this paper the equation was solved by means of Laplace transformation under different initial and boundary conditions. The dynamic surface adsorption F(t) for a surfactant solution, which was used to describe the diffusion-controlled adsorption kinetics at the solution surface, was derived. Different from the planar surface adsorption, the dynamic surface adsorption F(t) for the short time consists of two terms: one is the same as Ward-Tordai equation and the other reflects the geometric effect caused by the spherical bubble surface. This effect should not be neglected for the very small radius of the capillary. The equilibrium surface tension γeq and the dynamic surface tension γ(t) of aqueous C10E6 [CH3(CH2)9(OCH2CH2)6OH] solution at temperature 25℃ were measuredby means of Wilhelmy plate method and maximal bubble pressure method respectively. As t→ 0, the theoreticalanalysis is in good agreement with experimental results and the dependence of γ(t) on is linear. 展开更多
关键词 diffusion-controlled adsorption kinetics dynamic surface tension maximum bubble pressure method
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Modeling viscosity of methane,nitrogen,and hydrocarbon gas mixtures at ultra-high pressures and temperatures using group method of data handling and gene expression programming techniques 被引量:1
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作者 Farzaneh Rezaei Saeed Jafari +1 位作者 Abdolhossein Hemmati-Sarapardeh Amir H.Mohammadi 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2021年第4期431-445,共15页
Accurate gas viscosity determination is an important issue in the oil and gas industries.Experimental approaches for gas viscosity measurement are timeconsuming,expensive and hardly possible at high pressures and high... Accurate gas viscosity determination is an important issue in the oil and gas industries.Experimental approaches for gas viscosity measurement are timeconsuming,expensive and hardly possible at high pressures and high temperatures(HPHT).In this study,a number of correlations were developed to estimate gas viscosity by the use of group method of data handling(GMDH)type neural network and gene expression programming(GEP)techniques using a large data set containing more than 3000 experimental data points for methane,nitrogen,and hydrocarbon gas mixtures.It is worth mentioning that unlike many of viscosity correlations,the proposed ones in this study could compute gas viscosity at pressures ranging between 34 and 172 MPa and temperatures between 310 and 1300 K.Also,a comparison was performed between the results of these established models and the results of ten wellknown models reported in the literature.Average absolute relative errors of GMDH models were obtained 4.23%,0.64%,and 0.61%for hydrocarbon gas mixtures,methane,and nitrogen,respectively.In addition,graphical analyses indicate that the GMDH can predict gas viscosity with higher accuracy than GEP at HPHT conditions.Also,using leverage technique,valid,suspected and outlier data points were determined.Finally,trends of gas viscosity models at different conditions were evaluated. 展开更多
关键词 Gas Viscosity High pressure high temperature Group method of data handling Gene expression programming
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