Direct viscosification of CO_(2) offers promising alternative for mobility control and reduction in residual brine saturation,thus to improve the CO_(2) trapping in saline aquifers.Hydrocarbon oligomers,recognized for...Direct viscosification of CO_(2) offers promising alternative for mobility control and reduction in residual brine saturation,thus to improve the CO_(2) trapping in saline aquifers.Hydrocarbon oligomers,recognized for their exceptional properties,are considered as one of the most promising viscosifiers in displacement of brine-saturated porous media.However,the molecular-level mechanisms governing the solubility and viscosification of hydrocarbon oligomers in scCO_(2) remain poorly understood.In this study,we employ coarse-grained molecular models to advance our understanding in the effects of molecular structure of hydrocarbon oligomers on their solubility in scCO_(2).The coarse-grained models of five hydrocarbon oligomers with different numbers of methyl-branch(n-C32,P1D-2,P1D-3,P1D-6 and squalane)are established to investigate their effects on solubilization in scCO_(2).We demonstrate that the number of methyl groups has a monotonic correlation with the solubility of hydrocarbon oligomers when the molecular weights of oligomers are comparable.The radial distribution function reveals nC32,P1D and squalane are uniformly dispersed with separation distances of approximately 1.0–2.0 nm.The interaction energy between hydrocarbon oligomers and CO_(2) shows that the number of methylbranch in hydrocarbon oligomers can directly influence their solubility in scCO_(2).Molecular simulation results demonstrate that the interaction distances between the methyl-branch and CO_(2) are smaller than those of other molecular fragments.There are approximately 20%more CO_(2) molecules interacting with methyl-branch than with other parts.This work sets the stage for our future molecular dynamics study in viscosification by hydrocarbon oligomers with different branching length and interfacial phenomena in multiphase systems.展开更多
The mechanical properties of Mg–Al–Ca alloys are significantly affected by their Laves phases,including the Al_(2)Ca phase.Laves phases are generally considered to be brittle and have a detrimental effect on the duc...The mechanical properties of Mg–Al–Ca alloys are significantly affected by their Laves phases,including the Al_(2)Ca phase.Laves phases are generally considered to be brittle and have a detrimental effect on the ductility of Mg.Recently,the Al_(2)Ca phase was shown to undergo plastic deformation in a dilute Mg-Al-Ca alloy to increase the ductility and work hardening of the alloy.In the present study,we investigated the extent to which the deformation of Al_(2)Ca is driven by dislocations in the Mg matrix by simulating the interactions between the basal edge dislocations and Al_(2)Ca particles.In particular,the effects of the interparticle spacing,particle orientation,and particle size were considered.Shearing of small particles and dislocation cross-slips near large particles were observed.Both events contribute to strengthening,and accommodate to plasticity.The shear resistance of the dislocation to bypass the particles increased as the particle size increased.The critical resolved shear stress(CRSS)for activating dislocations and stacking faults was easier to reach for small Al_(2)Ca particles owing to the higher local shear stress,which is consistent with the experimental observations.Overall,this work elucidates the driving force for Al_(2)Ca particles in Mg–Al–Ca alloys to undergo plastic deformation.展开更多
The construction and operation of sulfur-containing gas storage are often more difficult than a non-sulfur storage facility due to the need to prevent environmental contamination from H_(2)S leaks,as well as the corro...The construction and operation of sulfur-containing gas storage are often more difficult than a non-sulfur storage facility due to the need to prevent environmental contamination from H_(2)S leaks,as well as the corrosive effects of H_(2)S on production facilities.Rapid elutriation of H_(2)S from the reservoir during the construction of the gas storage is an effective way to avoid these problems.However,the existing H_(2)S elutriation method has low efficiency and high economic cost,which limits the development of reconstructed gas storage of sulfur-containing gas reservoirs.To improve the efficiency of H_(2)S elutriation in sulfur-containing gas reservoirs and enhance the economic benefits,a numerical simulation model of multiphase flow components was established to study the migration law of H_(2)S in the multi-cycle operation of gas storage.Based on the H_(2)S migrate law,the displacement H_(2)S elutriation method was developed,and the elutriation mechanism and elutriation efficiency of the two methods were compared and analyzed.In addition,the main controlling factors affecting the H_(2)S elutriation efficiency were investigated,and the H_(2)S elutriation scheme of H gas storage was optimized.The results indicate that H_(2)S migrates between near-well and far-well regions under pressure differentials.The traditional H_(2)S elutriation method relies on concentration gradient diffusion,whereas the displacement elutriation approach leverages pressure differentials with higher H_(2)S elutriation efficiency.For the displacement elutriation method,higher reservoir permeability enhances the peak-shaving capacity of the gas storage but has a minor impact on H_(2)S elutriation when the formation permeability is between 30 and 100 mD.The elutriation efficiency is significantly higher when wells are drilled in the high structural parts of the reservoir compared to the low structural parts.Longer displacement elutriation time within a cycle improves H_(2)S elutriation efficiency but reduces the working gas volume of the storage.Therefore,the optimal displacement time for H gas storage is 60 days.An optimized H_(2)S elutriation scheme enabled the working gas to meet the national first-class natural gas standard within 10 cycles.This study elucidates H_(2)S migration patterns,H_(2)S elutriation mechanisms,and key influence factors on H_(2)S elutriation efficiency,offering valuable technical insights for sour gas storage operations.展开更多
The hybrid CO_(2) thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process.Using microscopic visualization experiments...The hybrid CO_(2) thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process.Using microscopic visualization experiments and molecular dynamics(MD)simulations,this study investigates the microscopic enhanced oil recovery(EOR)mechanisms underlying residual oil removal using hybrid CO_(2) thermal systems.Based on the experimental models for the occurrence of heavy oil,this study evaluates the performance of hybrid CO_(2) thermal systems under various conditions using MD simulations.The results demonstrate that introducing CO_(2) molecules into heavy oil can effectively penetrate and decompose dense aggregates that are originally formed on hydrophobic surfaces.A stable miscible hybrid CO_(2) thermal system,with a high effective distribution ratio of CO_(2),proficiently reduces the interaction energies between heavy oil and rock surfaces,as well as within heavy oil.A visualization analysis of the interactions reveals that strong van der Waals(vdW)attractions occur between CO_(2) and heavy oil molecules,effectively promoting the decomposition and swelling of heavy oil.This unlocks the residual oil on the hydrophobic surfaces.Considering the impacts of temperature and CO_(2) concentration,an optimal gas-to-steam injection ratio(here,the CO_(2):steam ratio)ranging between 1:6 and 1:9 is recommended.This study examines the microscopic mechanisms underlying the hybrid CO_(2) thermal technique at a molecular scale,providing a significant theoretical guide for its expanded application in EOR.展开更多
Drilling and blasting,characterized by their efficiency,ubiquity,and cost-effectiveness,have emerged as predominant techniques in rock excavation;however,they are accompanied by enormous destructive power.Accurately c...Drilling and blasting,characterized by their efficiency,ubiquity,and cost-effectiveness,have emerged as predominant techniques in rock excavation;however,they are accompanied by enormous destructive power.Accurately controlling the blasting energy and achieving the directional fracture of a rock mass have become common problems in the field.A two-dimensional blasting(2D blasting)technique was proposed that utilizes the characteristic that the tensile strength of a rock mass is significantly lower than its compressive strength.After blasting,only a 2D crack surface is generated along the predetermined direction,eliminating the damage to the reserved rock mass caused by conventional blasting.However,the interior of a natural rock mass is a"black box",and the process of crack propagation is difficult to capture,resulting in an unclear 2D blasting mechanism.To this end,a single-hole polymethyl methacrylate(PMMA)test piece was used to conduct a 2D blasting experiment with the help of a high-speed camera to capture the dynamic crack propagation process and the digital image correlation(DIC)method to analyze the evolution law of surface strain on the test piece.On this basis,a three-dimensional(3D)finite element model was established based on the progressive failure theory to simulate the stress,strain,damage,and displacement evolution process of the model under 2D blasting.The simulation results were consistent with the experimental results.The research results reveal the 2D blasting mechanism and provide theoretical support for the application of 2D blasting technology in the field of rock excavation.展开更多
Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the ...Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the crystal property of 12CaO·7Al2O3 (C12A7) cell were studied. The results show that the minerals containing Na2O mainly include 2Na2O·3CaO·5Al2O3 and Na2O·Al2O3, when the Na2O content in clinkers is less than 4.26% (mass fraction). The rest of Na2O is mainly doped in 12CaO·7Al2O3, which results in the decrease of the crystallinity of 12CaO·7Al2O3. The crystallinity of 2Na2O·3CaO·5Al2O3 is also inversely proportional to the Na2O content in clinkers. The formation processes of 2Na2O·3CaO·5Al2O3 and 12CaO·7Al2O3 can be divided into two ways, which are the direct reactions of raw materials and the transformation of CaO·Al2O3, respectively. The simulation shows that the covalency of O-Na bond in Na2O-doped 12CaO·7Al2O3 cell is weaker than those of O-Ca and O-Al bonds. The free energy of the unit cell increases because of Na2O doping, which results in the improvement of chemical activity of 12CaO·7Al2O3. The leaching efficiency of Al2O3 in clinker is improved from 34.81% to 88.17% when the Na2O content in clinkers increases from 0 to 4.26%.展开更多
The technology used to enhance coalbed methane(CBM) recovery by injecting CO_2(CO_2-ECBM) with heat, combining heat injection with CO_2 injection, is still in its infancy; therefore, theoretical studies of this CO_2-E...The technology used to enhance coalbed methane(CBM) recovery by injecting CO_2(CO_2-ECBM) with heat, combining heat injection with CO_2 injection, is still in its infancy; therefore, theoretical studies of this CO_2-ECBM technology should be perused. First, the coupling equations of the di usion–adsorption–seepage–heat transfer fields of gas are established. The displacement processes under di erent pressures and temperatures are simulated by COMSOL. Finally, the displacement effects, a comparison of the CO_2 storage capacity with the CH_4 output and the e ective influencing radius of CO_2 injection are analyzed and discussed. The results show that(1) the displacement pressure and temperature are two key factors influencing the CH_4 output and the CO_2 storage capacity, and the increase in the CO_2 storage capacity is more sensitive to temperature and pressure than the CH_4 output.(2) The gas flow direction is from the injection hole to the discharge hole during the displacement process, and the regions with high velocity are concentrated at the injection hole and the discharge hole.(3) A reduction in the CH_4 concentration and an increase in the CO_2 concentration are obvious during the displacement process.(4) The e ective influencing radius of injecting CO_2 with heat increases with the increase in time and pressure. The relationship between the e ective influencing radius and the injection time of CO_2 has a power exponential function, and there is a linear relationship between the functional coe cient and the injection pressure of CO_2. This numerical simulation study on enhancing CBM recovery by injecting CO_2 with heat can further promote the implementation of CO_2-ECBM project in deep coal seams.展开更多
API RP 7G-2标准、NS-2标准是钻探设备制造和检验中常用的两个标准,它们各自具有不同的特点和应用范围,了解这些差异对于确保钻探设备的安全性和可靠性至关重要。通过对二者的深入分析,识别其在钻柱常用构件方面的差异,探讨这些不同对...API RP 7G-2标准、NS-2标准是钻探设备制造和检验中常用的两个标准,它们各自具有不同的特点和应用范围,了解这些差异对于确保钻探设备的安全性和可靠性至关重要。通过对二者的深入分析,识别其在钻柱常用构件方面的差异,探讨这些不同对钻具作业整体表现的潜在影响,为同领域的技术进步与创新提供方向。展开更多
In this paper, we build up a three-dimensional model for CO2 storage in the deep reservoir. And this paper gives the mathematical formalism of combined geochemical and multi-phase flow. The results give us the informa...In this paper, we build up a three-dimensional model for CO2 storage in the deep reservoir. And this paper gives the mathematical formalism of combined geochemical and multi-phase flow. The results give us the information about geochemical changing caused by CO2 injection into aqueous, the dissolution or precipitation of reservoir minerals caused by aqueous components change, the change of water density, also the differences between this model and the simulation model without considering geochemical. The basic data for simulation is from York Reservoir.展开更多
In the present study, a great effort was made to improve the performance of an industrial liquefied petroleum gas(LPG) and natural gas liquid(NGL) production unit in one of the major gas refinery located at Pars speci...In the present study, a great effort was made to improve the performance of an industrial liquefied petroleum gas(LPG) and natural gas liquid(NGL) production unit in one of the major gas refinery located at Pars special economic zone in Iran. To demonstrate and obtain the optimal condition, the unit was simulated by using a steady-state flowsheet simulator, i.e. Aspen Plus, under different operational conditions. According to the simulation results,the unit was not operational under its optimal conditions due to some defects in the cooling system at top stage of the debutanizer tower(DBT) during hot and humid seasons. Additionally, the vapor pressure of produced LPG and accordingly the amount of its flaring were decreased by reducing the temperature of debutanizer tower at top stages. In the optimization section, the DBT condenser and reboiler heat duty, temperature, and pressure were regulated as adjustable parameters. The simulation results demonstrated that by applying the optimum suggestion in the hot months, the reflux stream temperature was reached about 55 ℃ which caused an efficient increment in LPG production(about 4%) with adjusting the propane component in LPG, based on the standard range as the plant criteria. Moreover, after applying modifications, about 750 t of LPG product was saved from flaring during five hot months of the year, which resulted in 360000 USD extra annual income for the company.Finally, from environmental point of view, this optimization caused to reduce 81 t of CO_2 emission to the environment. Therefore, the current investigation must be introduced as a friendly environmentally process.展开更多
Active faults are a common adverse geological phenomenon that can occur during tunnel excavation and has a very negative impact on the construction and operation of the tunnel.In this paper,the grade IV rock surroundi...Active faults are a common adverse geological phenomenon that can occur during tunnel excavation and has a very negative impact on the construction and operation of the tunnel.In this paper,the grade IV rock surrounding the cross-fault tunnel with poor geological conditions has been chosen for the study.The support capacity of 2^(nd) Generation-Negative Poisson’s Ratio(2G-NPR)bolt in an active fault tunnel has been carried out on the basis of relevant results obtained from the geomechanical model test and numerical investigations of failure model for existing unsupported fault tunnel.The investigation shows that surrounding rock of the tunnel is prone to shear deformation and crack formation along the fault,as a result,the rock mass on the upper part of the fault slips as a whole.Furthermore,small-scale deformation and loss of blocks are observed around the tunnel;however,the 2G-NPR bolt support is found to be helpful in keeping the overall tunnel intact without any damage and instability.Due to the blocking effect of fault,the stress of the surrounding rock on the upper and lower parts of the fault is significantly different,and the stress at the left shoulder of the tunnel is greater than that at the right shoulder.The asymmetrical arrangement of 2G-NPR bolts can effectively control the asymmetric deformation and instability of the surrounding rock.The present numerical scheme is in good agreement with the model test results,and can reasonably reflect the stress and displacement characteristics of the surrounding rock of the tunnel.In comparison to unsupported and ordinary PR(Poisson’s Ratio)bolt support,2G-NPR bolt can effectively limit the fault slip and control the stability of the surrounding rock of the fault tunnel.The research findings may serve as a guideline for the use of 2G-NPR bolts in fault tunnel support engineering.展开更多
Till now, there have been lots of researches on numerical simulation of vortex-induced vibration. Acceptable results have been obtained for fixed cylinders with low Reynolds number. However, for responses of 2-DOF vor...Till now, there have been lots of researches on numerical simulation of vortex-induced vibration. Acceptable results have been obtained for fixed cylinders with low Reynolds number. However, for responses of 2-DOF vortex-induced vibration with low mass ratio, the accuracy is not satisfactory, especially for the maximum amplitudes. In Jauvtis and Williamson＇s work, the maximum amplitude of the cylinder with low mass ratio m＊=2.6 can reach as large as 1.5D to be called as the ＂super-upper branch＂, but from current literatures, few simulation results can achieve such value, even fail to capture the upper branch. Besides, it is found that the amplitude decays too fast in the lower branch with the RANS-based turbulence model. The reason is likely to be the defects of the turbulence model itself in the prediction of unsteady separated flows as well as the unreasonable setting of the numerical simulation parameters. Aiming at above issues, a modified turbulence model is proposed in this paper, and the effect of the acceleration of flow field on the response of vortex-induced vibration is studied based on OpenFOAM. By analyzing the responses of amplitude, phase and trajectory, frequency and vortex mode, it is proved that the vortex-induced vibration can be predicted accurately with the modified turbulence model under appropriate flow field acceleration.展开更多
Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 20...Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 2005, the piercing process of 33Mn2V steel in Mannesmann mill is then simulated. The modeling results visualized the dynamic evolution of equivalent stress, especially inside the workpieee. It is shown that the non-uniform distribu- tion of stress on the internal and external surface of the workpiece is a distinct characteristic of processing tube pierc- ing. The numerical model was verified by comparing the values of calculated force parameters of the piercing process with those measured in laboratory eonditions. And it shows that the Kumar-type constitutive relationship meets the practical needs.展开更多
An accurate and efficient Synthetic Aperture Radar(SAR)raw data generator is of considerable value for testing system parameters and verifying imaging algorithms.Nevertheless,the existing simulator cannot exactly hand...An accurate and efficient Synthetic Aperture Radar(SAR)raw data generator is of considerable value for testing system parameters and verifying imaging algorithms.Nevertheless,the existing simulator cannot exactly handle the case of the fast moving targets in high squint geometry.As for the issue,the analytical expression for the two Dimensional(2-D)signal spectrum of moving targets is derived and a fast raw echo simulation method is proposed in this study.The proposed simulator can accommodate the moving targets in the high squint geometry,whose processing steps of the simulation are given in detail and its computational complexity is analyzed.The simulation data for static and moving targets are processed and analyzed,and the results are given to validate the effectiveness of the proposed approach.展开更多
2G-NPR bolt (the 2nd generation Negative Poisson’s Ratio bolt) is a new type of bolt with high strength, high toughness and no yield platform. It has signifcant efects on improving the shear strength of jointed rock ...2G-NPR bolt (the 2nd generation Negative Poisson’s Ratio bolt) is a new type of bolt with high strength, high toughness and no yield platform. It has signifcant efects on improving the shear strength of jointed rock mass and controlling the stability of surrounding rock. To achieve an accurate simulation of bolted joint shear tests, we have studied a numerical simulation method that takes into account the 2G-NPR bolt's tensile–shear fracture criterion. Firstly, the indoor experimental study on the tensile–shear mechanical properties of 2G-NPR bolt is carried out to explore its mechanical properties under diferent tensile–shear angles, and the fracture criterion of 2G-NPR bolt considering the tensile–shear angle is established. Then, a three-dimensional numerical simulation method considering the tensile–shear mechanical constitutive and fracture criterion of 2G-NPR bolt, the elastoplastic mechanical behavior of surrounding rock and the damage and deterioration of grouting body is proposed. The feasibility and accuracy of the method are verifed by comparing with the indoor shear test results of 2G-NPR bolt anchorage joints. Finally, based on the numerical simulation results, the deformation and stress of the bolt, the distribution of the plastic zone of the rock mass, the stress distribution and the damage of the grouting body are analyzed in detail. The research results can provide a good reference value for the practical engineering application and shear mechanical performance analysis of 2G-NPR bolt.展开更多
Thermo-hydro-mechanical-chemical(THMC)interactions are prevalent during CO_(2)geological sequestration(CGS).In this study,a sequential coupling THMC numerical simulation program was constructed,which can be used to ex...Thermo-hydro-mechanical-chemical(THMC)interactions are prevalent during CO_(2)geological sequestration(CGS).In this study,a sequential coupling THMC numerical simulation program was constructed,which can be used to explore the following issues of CGS:fluid and heat flow,solute transport;stresses,displacements and rock failures related to geo-mechanical effects;equilibrium and kinetic chemical reactions;chemical damage to mechanical properties of the rock.Then,the coupling program was applied to the Ordos CGS Project to study the formation response under the multifield interaction caused by CO_(2)injection.The simulation results show that the mechanical process dominates the short CO_(2)injection period.Specifically,the formation’s permeability near the injection well increases by 43%,due to the reduction of effective stress,which significantly promotes the lateral migration of CO_(2).When the injection rate exceeds 0.15 million tons per year,the cohesion of the reservoir rock is not enough to resist the shear force inside the rock and rock failure may occur.During the subsequent long-term sequestration period(200 years),the influence of mineral reactions gradually increases.Due to calcite dissolution,the shear modulus of caprock is predicted to decrease by 7.6%,which will to some extent increase the risk of rock failure.展开更多
The Guide sedimentary basin is located in the northeastern part of Qinghai-Xizang Plateau,which is rich in geothermal resources.However,exploitation of the geothermal resources has so far been limited,because of limit...The Guide sedimentary basin is located in the northeastern part of Qinghai-Xizang Plateau,which is rich in geothermal resources.However,exploitation of the geothermal resources has so far been limited,because of limited understanding of the resources quantity and storage gained from scientific researches.In this study,using a typical cross section across the basin and taking into account its geothermal and geological conditions,a new waterheat coupled model was built and associated modelling was done by the software TOUGH2.During modelling process,the accuracy and applicability of the model was confirmed through the calibration of relevant parameters for modelling the heat and water transport and the formation of geothermal reservoir across the basin,with particular focus on the Neogene geothermal field.Results show that the groundwater that flows from the basin margins to the center is heated by the Neogene and Paleogene sedimentary rocks with high geothermal gradients.Since the east-west extending fault F1 is conductive,it acts as preferential flow paths which on one hand provide additional and rapid flows to the thermal reservoir;and on the other hand,cool down the thermal water to a certain extent due to the infiltration of shallower water sources in the vicinity of the fault.Furthermore,the estimated geothermal resources quantity is close to that of previous studies.In comparison with the Paleogene rock formations,the Neogene geothermal reservoir shows a better nature in terms of water content,aquifer permeability and resources exploitability,although the resource quantity of the Paleogene reservoir is considerable.展开更多
Debris flows are rapid mass movements with a mixture of rock,soil and water.High-intensity rainfall events have triggered multiple debris flows around the globe,making it an important concern from the disaster managem...Debris flows are rapid mass movements with a mixture of rock,soil and water.High-intensity rainfall events have triggered multiple debris flows around the globe,making it an important concern from the disaster management perspective.This study presents a numerical model called debris flow simulation 2D(DFS 2D)and applicability of the proposed model is investigated through the values of the model parameters used for the reproduction of an occurred debris flow at Yindongzi gully in China on 13 August 2010.The model can be used to simulate debris flows using three different rheologies and has a userfriendly interface for providing the inputs.Using DFS 2D,flow parameters can be estimated with respect to space and time.The values of the flow resistance parameters of model,dry-Coulomb and turbulent friction,were calibrated through the back analysis and the values obtained are 0.1 and 1000 m/s^(2),respectively.Two new methods of calibration are proposed in this study,considering the crosssectional area of flow and topographical changes induced by the debris flow.The proposed methods of calibration provide an effective solution to the cumulative errors induced by coarse-resolution digital elevation models(DEMs)in numerical modelling of debris flows.The statistical indices such as Willmott's index of agreement,mean-absolute-error,and normalized-root-mean-square-error of the calibrated model are 0.5,1.02 and 1.44,respectively.The comparison between simulated and observed values of topographic changes indicates that DFS 2D provides satisfactory results and can be used for dynamic modelling of debris flows.展开更多
In this work, a two-dimensional fluid model has been employed to study the characteristics of Ar/O2 radio frequency（RF） inductively coupled plasma discharges. The emphasis of this work has been put on the influence ...In this work, a two-dimensional fluid model has been employed to study the characteristics of Ar/O2 radio frequency（RF） inductively coupled plasma discharges. The emphasis of this work has been put on the influence of the external parameters（i.e., the RF power, the pressure, and the Ar/O2 gas ratio） on the plasma properties. The numerical results show that the RF power has a significant influence on the amplitude of the plasma density rather than on the spatial distribution.However, the pressure and the Ar/O2 gas ratio affect not only the amplitude of the plasma density, but also the spatial uniformity. Finally, the comparison between the simulation results and the experimental data has been made at different gas pressures and oxygen contents, and a good agreement has been achieved.展开更多
Based on the logical causal relationship and taking Liaoning Province, China, which is the Chinese traditional industrial base and is in the stage of accelerated urbanisation, as a case study, this study builds the ＇...Based on the logical causal relationship and taking Liaoning Province, China, which is the Chinese traditional industrial base and is in the stage of accelerated urbanisation, as a case study, this study builds the ＇Urbanisation-Energy Consumption-COn Emissions System Dynamics （UEC-SD）＇ model using a system dynamics method. The UEC-SD model is applied to analyse the effect of the ar- banisation process on the regional energy structure and CO2 emissions, followed by simulation of future production and living energy consumption structure as well as the evolutionary trend of CO2 emissions of three urbanisation scenarios （low speed, intermediate speed and high speed） under the assumed boundary conditions in urban and rural areas of Liaoning Province, China. The results show that the urbanisation process can alter production and the living energy consumption structure and thereby change regional CO2 emissions. An increase in the urbanisation rate in case area will lead to regional COz emissions rising in the short term, but when the urbanisation rate approaches 80%, CO2 emissions will reach a peak value and then decrease. Comparison of different urbanisation rates showed that pro- duction and living energy consumption exhibit different directions of change and rules in urban and rural areas. The effect of urbanisa- tion on CO2 emissions and energy structure is not direct, and urbanisation can increase the differences in energy and CO2 emissions between urban and rural areas caused by the industrial structure, technical level and other factors.展开更多
基金the financial support and funding provided by the National Natural Science Foundation of China(Youth Talent Program,Key Special Project,Grant No.52341401 and Distinguished Scholar Program with a Grant No.52425402)High-level Start-up Funding from Peking University Shenzhen Graduate School,Shenzhen Science and Technology Foundation(Grant No.JCYJ20230807120807016)+2 种基金High-level Startup Funding from China University of Petroleum-Beijing(Grant No.2462024YJRC033)the China Postdoctoral Science(CPS)Foundation(Certificate No.2024M750106)the Postdoctoral Fellowship Program of CPS(Grant No.GZC20240051)。
文摘Direct viscosification of CO_(2) offers promising alternative for mobility control and reduction in residual brine saturation,thus to improve the CO_(2) trapping in saline aquifers.Hydrocarbon oligomers,recognized for their exceptional properties,are considered as one of the most promising viscosifiers in displacement of brine-saturated porous media.However,the molecular-level mechanisms governing the solubility and viscosification of hydrocarbon oligomers in scCO_(2) remain poorly understood.In this study,we employ coarse-grained molecular models to advance our understanding in the effects of molecular structure of hydrocarbon oligomers on their solubility in scCO_(2).The coarse-grained models of five hydrocarbon oligomers with different numbers of methyl-branch(n-C32,P1D-2,P1D-3,P1D-6 and squalane)are established to investigate their effects on solubilization in scCO_(2).We demonstrate that the number of methyl groups has a monotonic correlation with the solubility of hydrocarbon oligomers when the molecular weights of oligomers are comparable.The radial distribution function reveals nC32,P1D and squalane are uniformly dispersed with separation distances of approximately 1.0–2.0 nm.The interaction energy between hydrocarbon oligomers and CO_(2) shows that the number of methylbranch in hydrocarbon oligomers can directly influence their solubility in scCO_(2).Molecular simulation results demonstrate that the interaction distances between the methyl-branch and CO_(2) are smaller than those of other molecular fragments.There are approximately 20%more CO_(2) molecules interacting with methyl-branch than with other parts.This work sets the stage for our future molecular dynamics study in viscosification by hydrocarbon oligomers with different branching length and interfacial phenomena in multiphase systems.
基金funded by the National Natural Science Foundation of China(nos.51631006 and 51825101)。
文摘The mechanical properties of Mg–Al–Ca alloys are significantly affected by their Laves phases,including the Al_(2)Ca phase.Laves phases are generally considered to be brittle and have a detrimental effect on the ductility of Mg.Recently,the Al_(2)Ca phase was shown to undergo plastic deformation in a dilute Mg-Al-Ca alloy to increase the ductility and work hardening of the alloy.In the present study,we investigated the extent to which the deformation of Al_(2)Ca is driven by dislocations in the Mg matrix by simulating the interactions between the basal edge dislocations and Al_(2)Ca particles.In particular,the effects of the interparticle spacing,particle orientation,and particle size were considered.Shearing of small particles and dislocation cross-slips near large particles were observed.Both events contribute to strengthening,and accommodate to plasticity.The shear resistance of the dislocation to bypass the particles increased as the particle size increased.The critical resolved shear stress(CRSS)for activating dislocations and stacking faults was easier to reach for small Al_(2)Ca particles owing to the higher local shear stress,which is consistent with the experimental observations.Overall,this work elucidates the driving force for Al_(2)Ca particles in Mg–Al–Ca alloys to undergo plastic deformation.
基金supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202401501,KJZD-M202401501).
文摘The construction and operation of sulfur-containing gas storage are often more difficult than a non-sulfur storage facility due to the need to prevent environmental contamination from H_(2)S leaks,as well as the corrosive effects of H_(2)S on production facilities.Rapid elutriation of H_(2)S from the reservoir during the construction of the gas storage is an effective way to avoid these problems.However,the existing H_(2)S elutriation method has low efficiency and high economic cost,which limits the development of reconstructed gas storage of sulfur-containing gas reservoirs.To improve the efficiency of H_(2)S elutriation in sulfur-containing gas reservoirs and enhance the economic benefits,a numerical simulation model of multiphase flow components was established to study the migration law of H_(2)S in the multi-cycle operation of gas storage.Based on the H_(2)S migrate law,the displacement H_(2)S elutriation method was developed,and the elutriation mechanism and elutriation efficiency of the two methods were compared and analyzed.In addition,the main controlling factors affecting the H_(2)S elutriation efficiency were investigated,and the H_(2)S elutriation scheme of H gas storage was optimized.The results indicate that H_(2)S migrates between near-well and far-well regions under pressure differentials.The traditional H_(2)S elutriation method relies on concentration gradient diffusion,whereas the displacement elutriation approach leverages pressure differentials with higher H_(2)S elutriation efficiency.For the displacement elutriation method,higher reservoir permeability enhances the peak-shaving capacity of the gas storage but has a minor impact on H_(2)S elutriation when the formation permeability is between 30 and 100 mD.The elutriation efficiency is significantly higher when wells are drilled in the high structural parts of the reservoir compared to the low structural parts.Longer displacement elutriation time within a cycle improves H_(2)S elutriation efficiency but reduces the working gas volume of the storage.Therefore,the optimal displacement time for H gas storage is 60 days.An optimized H_(2)S elutriation scheme enabled the working gas to meet the national first-class natural gas standard within 10 cycles.This study elucidates H_(2)S migration patterns,H_(2)S elutriation mechanisms,and key influence factors on H_(2)S elutriation efficiency,offering valuable technical insights for sour gas storage operations.
基金financially supported by the National Natural Science Foundation of China(No.U20B6003)the China Scholarship Council(No.202306440015)a project of the China Petroleum&Chemical Corporation(No.P22174)。
文摘The hybrid CO_(2) thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process.Using microscopic visualization experiments and molecular dynamics(MD)simulations,this study investigates the microscopic enhanced oil recovery(EOR)mechanisms underlying residual oil removal using hybrid CO_(2) thermal systems.Based on the experimental models for the occurrence of heavy oil,this study evaluates the performance of hybrid CO_(2) thermal systems under various conditions using MD simulations.The results demonstrate that introducing CO_(2) molecules into heavy oil can effectively penetrate and decompose dense aggregates that are originally formed on hydrophobic surfaces.A stable miscible hybrid CO_(2) thermal system,with a high effective distribution ratio of CO_(2),proficiently reduces the interaction energies between heavy oil and rock surfaces,as well as within heavy oil.A visualization analysis of the interactions reveals that strong van der Waals(vdW)attractions occur between CO_(2) and heavy oil molecules,effectively promoting the decomposition and swelling of heavy oil.This unlocks the residual oil on the hydrophobic surfaces.Considering the impacts of temperature and CO_(2) concentration,an optimal gas-to-steam injection ratio(here,the CO_(2):steam ratio)ranging between 1:6 and 1:9 is recommended.This study examines the microscopic mechanisms underlying the hybrid CO_(2) thermal technique at a molecular scale,providing a significant theoretical guide for its expanded application in EOR.
基金supported by the National Natural Science Foundation of China(Grant Nos.52404155 and 52304111)State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining&Technology,Beijing(Grant No.XD2024006).
文摘Drilling and blasting,characterized by their efficiency,ubiquity,and cost-effectiveness,have emerged as predominant techniques in rock excavation;however,they are accompanied by enormous destructive power.Accurately controlling the blasting energy and achieving the directional fracture of a rock mass have become common problems in the field.A two-dimensional blasting(2D blasting)technique was proposed that utilizes the characteristic that the tensile strength of a rock mass is significantly lower than its compressive strength.After blasting,only a 2D crack surface is generated along the predetermined direction,eliminating the damage to the reserved rock mass caused by conventional blasting.However,the interior of a natural rock mass is a"black box",and the process of crack propagation is difficult to capture,resulting in an unclear 2D blasting mechanism.To this end,a single-hole polymethyl methacrylate(PMMA)test piece was used to conduct a 2D blasting experiment with the help of a high-speed camera to capture the dynamic crack propagation process and the digital image correlation(DIC)method to analyze the evolution law of surface strain on the test piece.On this basis,a three-dimensional(3D)finite element model was established based on the progressive failure theory to simulate the stress,strain,damage,and displacement evolution process of the model under 2D blasting.The simulation results were consistent with the experimental results.The research results reveal the 2D blasting mechanism and provide theoretical support for the application of 2D blasting technology in the field of rock excavation.
基金Projects(51174054,51104041,51374065)supported by the National Natural Science Foundation of ChinaProject(N130402010)supported by the Fundamental Research Funds for the Central Universities of China
文摘Calcium aluminate clinkers doped with Na2O were synthesized using analytically pure reagents CaCO3, Al2O3, SiO2 and Na2CO3. The effects of Na2O-doping on the formation mechanism of calcium aluminate compounds and the crystal property of 12CaO·7Al2O3 (C12A7) cell were studied. The results show that the minerals containing Na2O mainly include 2Na2O·3CaO·5Al2O3 and Na2O·Al2O3, when the Na2O content in clinkers is less than 4.26% (mass fraction). The rest of Na2O is mainly doped in 12CaO·7Al2O3, which results in the decrease of the crystallinity of 12CaO·7Al2O3. The crystallinity of 2Na2O·3CaO·5Al2O3 is also inversely proportional to the Na2O content in clinkers. The formation processes of 2Na2O·3CaO·5Al2O3 and 12CaO·7Al2O3 can be divided into two ways, which are the direct reactions of raw materials and the transformation of CaO·Al2O3, respectively. The simulation shows that the covalency of O-Na bond in Na2O-doped 12CaO·7Al2O3 cell is weaker than those of O-Ca and O-Al bonds. The free energy of the unit cell increases because of Na2O doping, which results in the improvement of chemical activity of 12CaO·7Al2O3. The leaching efficiency of Al2O3 in clinker is improved from 34.81% to 88.17% when the Na2O content in clinkers increases from 0 to 4.26%.
基金financially supported by the National Natural Science Foundation of China(No.41330638)
文摘The technology used to enhance coalbed methane(CBM) recovery by injecting CO_2(CO_2-ECBM) with heat, combining heat injection with CO_2 injection, is still in its infancy; therefore, theoretical studies of this CO_2-ECBM technology should be perused. First, the coupling equations of the di usion–adsorption–seepage–heat transfer fields of gas are established. The displacement processes under di erent pressures and temperatures are simulated by COMSOL. Finally, the displacement effects, a comparison of the CO_2 storage capacity with the CH_4 output and the e ective influencing radius of CO_2 injection are analyzed and discussed. The results show that(1) the displacement pressure and temperature are two key factors influencing the CH_4 output and the CO_2 storage capacity, and the increase in the CO_2 storage capacity is more sensitive to temperature and pressure than the CH_4 output.(2) The gas flow direction is from the injection hole to the discharge hole during the displacement process, and the regions with high velocity are concentrated at the injection hole and the discharge hole.(3) A reduction in the CH_4 concentration and an increase in the CO_2 concentration are obvious during the displacement process.(4) The e ective influencing radius of injecting CO_2 with heat increases with the increase in time and pressure. The relationship between the e ective influencing radius and the injection time of CO_2 has a power exponential function, and there is a linear relationship between the functional coe cient and the injection pressure of CO_2. This numerical simulation study on enhancing CBM recovery by injecting CO_2 with heat can further promote the implementation of CO_2-ECBM project in deep coal seams.
基金Supported by the National Natural Science Foundation of China （50904073） and CNPC Innovation Foundation （2008D-5006-02-06）.
文摘In this paper, we build up a three-dimensional model for CO2 storage in the deep reservoir. And this paper gives the mathematical formalism of combined geochemical and multi-phase flow. The results give us the information about geochemical changing caused by CO2 injection into aqueous, the dissolution or precipitation of reservoir minerals caused by aqueous components change, the change of water density, also the differences between this model and the simulation model without considering geochemical. The basic data for simulation is from York Reservoir.
文摘In the present study, a great effort was made to improve the performance of an industrial liquefied petroleum gas(LPG) and natural gas liquid(NGL) production unit in one of the major gas refinery located at Pars special economic zone in Iran. To demonstrate and obtain the optimal condition, the unit was simulated by using a steady-state flowsheet simulator, i.e. Aspen Plus, under different operational conditions. According to the simulation results,the unit was not operational under its optimal conditions due to some defects in the cooling system at top stage of the debutanizer tower(DBT) during hot and humid seasons. Additionally, the vapor pressure of produced LPG and accordingly the amount of its flaring were decreased by reducing the temperature of debutanizer tower at top stages. In the optimization section, the DBT condenser and reboiler heat duty, temperature, and pressure were regulated as adjustable parameters. The simulation results demonstrated that by applying the optimum suggestion in the hot months, the reflux stream temperature was reached about 55 ℃ which caused an efficient increment in LPG production(about 4%) with adjusting the propane component in LPG, based on the standard range as the plant criteria. Moreover, after applying modifications, about 750 t of LPG product was saved from flaring during five hot months of the year, which resulted in 360000 USD extra annual income for the company.Finally, from environmental point of view, this optimization caused to reduce 81 t of CO_2 emission to the environment. Therefore, the current investigation must be introduced as a friendly environmentally process.
基金supported by the National Natural Science Foundation of China(NSFC)(41941018)the Program of China Scholarship Council(202106430031)。
文摘Active faults are a common adverse geological phenomenon that can occur during tunnel excavation and has a very negative impact on the construction and operation of the tunnel.In this paper,the grade IV rock surrounding the cross-fault tunnel with poor geological conditions has been chosen for the study.The support capacity of 2^(nd) Generation-Negative Poisson’s Ratio(2G-NPR)bolt in an active fault tunnel has been carried out on the basis of relevant results obtained from the geomechanical model test and numerical investigations of failure model for existing unsupported fault tunnel.The investigation shows that surrounding rock of the tunnel is prone to shear deformation and crack formation along the fault,as a result,the rock mass on the upper part of the fault slips as a whole.Furthermore,small-scale deformation and loss of blocks are observed around the tunnel;however,the 2G-NPR bolt support is found to be helpful in keeping the overall tunnel intact without any damage and instability.Due to the blocking effect of fault,the stress of the surrounding rock on the upper and lower parts of the fault is significantly different,and the stress at the left shoulder of the tunnel is greater than that at the right shoulder.The asymmetrical arrangement of 2G-NPR bolts can effectively control the asymmetric deformation and instability of the surrounding rock.The present numerical scheme is in good agreement with the model test results,and can reasonably reflect the stress and displacement characteristics of the surrounding rock of the tunnel.In comparison to unsupported and ordinary PR(Poisson’s Ratio)bolt support,2G-NPR bolt can effectively limit the fault slip and control the stability of the surrounding rock of the fault tunnel.The research findings may serve as a guideline for the use of 2G-NPR bolts in fault tunnel support engineering.
基金financially supported by the National Natural Science Foundation of China(Grant No.51509045)
文摘Till now, there have been lots of researches on numerical simulation of vortex-induced vibration. Acceptable results have been obtained for fixed cylinders with low Reynolds number. However, for responses of 2-DOF vortex-induced vibration with low mass ratio, the accuracy is not satisfactory, especially for the maximum amplitudes. In Jauvtis and Williamson＇s work, the maximum amplitude of the cylinder with low mass ratio m＊=2.6 can reach as large as 1.5D to be called as the ＂super-upper branch＂, but from current literatures, few simulation results can achieve such value, even fail to capture the upper branch. Besides, it is found that the amplitude decays too fast in the lower branch with the RANS-based turbulence model. The reason is likely to be the defects of the turbulence model itself in the prediction of unsteady separated flows as well as the unreasonable setting of the numerical simulation parameters. Aiming at above issues, a modified turbulence model is proposed in this paper, and the effect of the acceleration of flow field on the response of vortex-induced vibration is studied based on OpenFOAM. By analyzing the responses of amplitude, phase and trajectory, frequency and vortex mode, it is proved that the vortex-induced vibration can be predicted accurately with the modified turbulence model under appropriate flow field acceleration.
基金Item Sponsored by Tianjin Natural Science Foundation of China(06YFJ MJC02200,11JCZDJC22600)
文摘Based on test data from the hot forge experiments on Gleeble 1500, a Kumar type constitutive equation for 33Mn2V steel is established. Applying this constitutive equation in commercial FEM software of MSC/SuperForm 2005, the piercing process of 33Mn2V steel in Mannesmann mill is then simulated. The modeling results visualized the dynamic evolution of equivalent stress, especially inside the workpieee. It is shown that the non-uniform distribu- tion of stress on the internal and external surface of the workpiece is a distinct characteristic of processing tube pierc- ing. The numerical model was verified by comparing the values of calculated force parameters of the piercing process with those measured in laboratory eonditions. And it shows that the Kumar-type constitutive relationship meets the practical needs.
文摘An accurate and efficient Synthetic Aperture Radar(SAR)raw data generator is of considerable value for testing system parameters and verifying imaging algorithms.Nevertheless,the existing simulator cannot exactly handle the case of the fast moving targets in high squint geometry.As for the issue,the analytical expression for the two Dimensional(2-D)signal spectrum of moving targets is derived and a fast raw echo simulation method is proposed in this study.The proposed simulator can accommodate the moving targets in the high squint geometry,whose processing steps of the simulation are given in detail and its computational complexity is analyzed.The simulation data for static and moving targets are processed and analyzed,and the results are given to validate the effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(NSFC)(41941018).
文摘2G-NPR bolt (the 2nd generation Negative Poisson’s Ratio bolt) is a new type of bolt with high strength, high toughness and no yield platform. It has signifcant efects on improving the shear strength of jointed rock mass and controlling the stability of surrounding rock. To achieve an accurate simulation of bolted joint shear tests, we have studied a numerical simulation method that takes into account the 2G-NPR bolt's tensile–shear fracture criterion. Firstly, the indoor experimental study on the tensile–shear mechanical properties of 2G-NPR bolt is carried out to explore its mechanical properties under diferent tensile–shear angles, and the fracture criterion of 2G-NPR bolt considering the tensile–shear angle is established. Then, a three-dimensional numerical simulation method considering the tensile–shear mechanical constitutive and fracture criterion of 2G-NPR bolt, the elastoplastic mechanical behavior of surrounding rock and the damage and deterioration of grouting body is proposed. The feasibility and accuracy of the method are verifed by comparing with the indoor shear test results of 2G-NPR bolt anchorage joints. Finally, based on the numerical simulation results, the deformation and stress of the bolt, the distribution of the plastic zone of the rock mass, the stress distribution and the damage of the grouting body are analyzed in detail. The research results can provide a good reference value for the practical engineering application and shear mechanical performance analysis of 2G-NPR bolt.
基金jointly supported by the National Natural Science Foundation of China(Grant No.42141013)the CNPC Innovation Found(2021 D002-1102)the China Postdoctoral Science Foundation(No.2021M701379)。
文摘Thermo-hydro-mechanical-chemical(THMC)interactions are prevalent during CO_(2)geological sequestration(CGS).In this study,a sequential coupling THMC numerical simulation program was constructed,which can be used to explore the following issues of CGS:fluid and heat flow,solute transport;stresses,displacements and rock failures related to geo-mechanical effects;equilibrium and kinetic chemical reactions;chemical damage to mechanical properties of the rock.Then,the coupling program was applied to the Ordos CGS Project to study the formation response under the multifield interaction caused by CO_(2)injection.The simulation results show that the mechanical process dominates the short CO_(2)injection period.Specifically,the formation’s permeability near the injection well increases by 43%,due to the reduction of effective stress,which significantly promotes the lateral migration of CO_(2).When the injection rate exceeds 0.15 million tons per year,the cohesion of the reservoir rock is not enough to resist the shear force inside the rock and rock failure may occur.During the subsequent long-term sequestration period(200 years),the influence of mineral reactions gradually increases.Due to calcite dissolution,the shear modulus of caprock is predicted to decrease by 7.6%,which will to some extent increase the risk of rock failure.
基金This work was supported by grants from National Natural Science Foundation of China(No.41402231)geothermal survey project of China Geological Survey(No.DD20190128)+1 种基金Natural Science Foundation of Hebei Province China(No.D2019330003)S&T Program of Hebei China(No.20374201D).
文摘The Guide sedimentary basin is located in the northeastern part of Qinghai-Xizang Plateau,which is rich in geothermal resources.However,exploitation of the geothermal resources has so far been limited,because of limited understanding of the resources quantity and storage gained from scientific researches.In this study,using a typical cross section across the basin and taking into account its geothermal and geological conditions,a new waterheat coupled model was built and associated modelling was done by the software TOUGH2.During modelling process,the accuracy and applicability of the model was confirmed through the calibration of relevant parameters for modelling the heat and water transport and the formation of geothermal reservoir across the basin,with particular focus on the Neogene geothermal field.Results show that the groundwater that flows from the basin margins to the center is heated by the Neogene and Paleogene sedimentary rocks with high geothermal gradients.Since the east-west extending fault F1 is conductive,it acts as preferential flow paths which on one hand provide additional and rapid flows to the thermal reservoir;and on the other hand,cool down the thermal water to a certain extent due to the infiltration of shallower water sources in the vicinity of the fault.Furthermore,the estimated geothermal resources quantity is close to that of previous studies.In comparison with the Paleogene rock formations,the Neogene geothermal reservoir shows a better nature in terms of water content,aquifer permeability and resources exploitability,although the resource quantity of the Paleogene reservoir is considerable.
基金financially supported by Department of Space,India(Grant No.ISRO/RES/4/663/18-19)。
文摘Debris flows are rapid mass movements with a mixture of rock,soil and water.High-intensity rainfall events have triggered multiple debris flows around the globe,making it an important concern from the disaster management perspective.This study presents a numerical model called debris flow simulation 2D(DFS 2D)and applicability of the proposed model is investigated through the values of the model parameters used for the reproduction of an occurred debris flow at Yindongzi gully in China on 13 August 2010.The model can be used to simulate debris flows using three different rheologies and has a userfriendly interface for providing the inputs.Using DFS 2D,flow parameters can be estimated with respect to space and time.The values of the flow resistance parameters of model,dry-Coulomb and turbulent friction,were calibrated through the back analysis and the values obtained are 0.1 and 1000 m/s^(2),respectively.Two new methods of calibration are proposed in this study,considering the crosssectional area of flow and topographical changes induced by the debris flow.The proposed methods of calibration provide an effective solution to the cumulative errors induced by coarse-resolution digital elevation models(DEMs)in numerical modelling of debris flows.The statistical indices such as Willmott's index of agreement,mean-absolute-error,and normalized-root-mean-square-error of the calibrated model are 0.5,1.02 and 1.44,respectively.The comparison between simulated and observed values of topographic changes indicates that DFS 2D provides satisfactory results and can be used for dynamic modelling of debris flows.
基金Project supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011ZX02403-001)the National Natural Science Foundation of China(Grant No.11205025)
文摘In this work, a two-dimensional fluid model has been employed to study the characteristics of Ar/O2 radio frequency（RF） inductively coupled plasma discharges. The emphasis of this work has been put on the influence of the external parameters（i.e., the RF power, the pressure, and the Ar/O2 gas ratio） on the plasma properties. The numerical results show that the RF power has a significant influence on the amplitude of the plasma density rather than on the spatial distribution.However, the pressure and the Ar/O2 gas ratio affect not only the amplitude of the plasma density, but also the spatial uniformity. Finally, the comparison between the simulation results and the experimental data has been made at different gas pressures and oxygen contents, and a good agreement has been achieved.
基金Under the auspices of National Natural Science Foundation of China(No.41301637,41101117,41271186)Key Program of National Natural Science Foundation of China(No.71133003)
文摘Based on the logical causal relationship and taking Liaoning Province, China, which is the Chinese traditional industrial base and is in the stage of accelerated urbanisation, as a case study, this study builds the ＇Urbanisation-Energy Consumption-COn Emissions System Dynamics （UEC-SD）＇ model using a system dynamics method. The UEC-SD model is applied to analyse the effect of the ar- banisation process on the regional energy structure and CO2 emissions, followed by simulation of future production and living energy consumption structure as well as the evolutionary trend of CO2 emissions of three urbanisation scenarios （low speed, intermediate speed and high speed） under the assumed boundary conditions in urban and rural areas of Liaoning Province, China. The results show that the urbanisation process can alter production and the living energy consumption structure and thereby change regional CO2 emissions. An increase in the urbanisation rate in case area will lead to regional COz emissions rising in the short term, but when the urbanisation rate approaches 80%, CO2 emissions will reach a peak value and then decrease. Comparison of different urbanisation rates showed that pro- duction and living energy consumption exhibit different directions of change and rules in urban and rural areas. The effect of urbanisa- tion on CO2 emissions and energy structure is not direct, and urbanisation can increase the differences in energy and CO2 emissions between urban and rural areas caused by the industrial structure, technical level and other factors.
