Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mi...Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mixing by means of the fuel jet developmentperiphery charts obtained by the high speed photography with a modeling test device deve-loped by authors,and to examine it by the tests on a single cylinder diesel engine.Resultsand Conclusion The mixing process can be divided into four phases.The optimizing range of the ration of the inner chamber diameter to the cylinder bore,d2/D,is 0.4-0.7; and the outerchamber diameter,d1 the height of the circular ridge to the piston top face,h1,the radius of outer/inner chamber circle,R1,R2 ,the max depth of outer/inner chamber bowl,H1,H2,etc. are also important展开更多
An algorithm named InterOpt for optimizing operational parameters is proposed based on interpretable machine learning,and is demonstrated via optimization of shale gas development.InterOpt consists of three parts:a ne...An algorithm named InterOpt for optimizing operational parameters is proposed based on interpretable machine learning,and is demonstrated via optimization of shale gas development.InterOpt consists of three parts:a neural network is used to construct an emulator of the actual drilling and hydraulic fracturing process in the vector space(i.e.,virtual environment);:the Sharpley value method in inter-pretable machine learning is applied to analyzing the impact of geological and operational parameters in each well(i.e.,single well feature impact analysis):and ensemble randomized maximum likelihood(EnRML)is conducted to optimize the operational parameters to comprehensively improve the efficiency of shale gas development and reduce the average cost.In the experiment,InterOpt provides different drilling and fracturing plans for each well according to its specific geological conditions,and finally achieves an average cost reduction of 9.7%for a case study with 104 wells.展开更多
Sampling ports were firstly drilled on a ZGM95 coal mill in the power plant in China, and the coal samples from various points in the pulverizer were collected under the different operation conditions. The prop- erty ...Sampling ports were firstly drilled on a ZGM95 coal mill in the power plant in China, and the coal samples from various points in the pulverizer were collected under the different operation conditions. The prop- erty of the sampling material from the mill was analyzed, applying the float-sink test, size distribution analysis, proximate analysis and so on. It was indicated that the ＋250 I^m fraction in the pulverized fuel accounted for only 0.02%, while it was 83.2% in the new feed. The circulating ratio and coal flow in the separator and the cone zone were calculated using the mass balance of the circulating load. So, the cir- culating ratio in the separator of the pulverizer was between 8 and 13, and the circulating ratio, the feed flow of separator and cone zone all raised with the increase of the air volume. Furthermore, the parameters of the separation functions were obtained based on the fitting method. It was shown that the mean value of the shape factor B was 0.7617, and the parameter D which is the particle size at 50% cumulative yield in the separator almost kept unchanged.展开更多
We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experime...We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experiment. Saturation broadening spectra of the ground state hyperfine transition of trapped 199Hg＋ ions are measured and analyzed. The value of the optimal microwave power is obtained by using the proposed method and is verified. Rabi oscillations decay spectra of trapped 199Hg＋ ions are observed and the optimal microwave irradiation time for the maximum transition signal intensity is determined. This work will help to improve the short-term frequency stability of the mercury ion microwave frequency standard.展开更多
In the present work,pulsed gas–liquid hybrid discharge plasma coupled with graphene/Cd S catalyst was evaluated to eliminate bisphenol A(BPA)in wastewater.The optimization of a series of process parameters was perfor...In the present work,pulsed gas–liquid hybrid discharge plasma coupled with graphene/Cd S catalyst was evaluated to eliminate bisphenol A(BPA)in wastewater.The optimization of a series of process parameters was performed in terms of BPA degradation performance.The experimental results demonstrated that nearly 90%of BPA(20 mg l^(-1))in the synthetic wastewater(p H=7.5,σ=10μS m^(-1))was degraded by the plasma catalytic system over 0.2 g l^(-1)graphene/Cd S at 19k V with a 4 l min^(-1)air flow rate and 10 mm electrode gap within 60 min.The BPA removal rate increased with increasing the discharge voltage and decreasing the initial BPA concentration or solution conductivity.Nevertheless,either too high or too low an air flow rate,electrode gap,catalyst dosage or initial solution p H would lead to a decrease in BPA degradation.Moreover,optical emission spectroscopy was used to gain information on short-lived reactive species formed from the pulsed gas–liquid hybrid discharge plasma system.The results indicated the existence of several highly oxidative free radicals such as·O and·OH.Finally,the activation pathway of O_(3)on the catalyst surface was analyzed by density functional theory.展开更多
CO_(2) dry fracturing is a promising alternative method to water fracturing in tight gas reservoirs,especially in water-scarce areas such as the Loess Plateau.The CO_(2) flowback efficiency is a critical factor that a...CO_(2) dry fracturing is a promising alternative method to water fracturing in tight gas reservoirs,especially in water-scarce areas such as the Loess Plateau.The CO_(2) flowback efficiency is a critical factor that affects the final gas production effect.However,there have been few studies focusing on the flowback characteristics after CO_(2) dry fracturing.In this study,an extensive core-to-field scale study was conducted to investigate CO_(2) flowback characteristics and CH_(4) production behavior.Firstly,to investigate the impact of core properties and production conditions on CO_(2) flowback,a series of laboratory experiments at the core scale were conducted.Then,the key factors affecting the flowback were analyzed using the grey correlation method based on field data.Finally,taking the construction parameters of Well S60 as an example,a dual-permeability model was used to characterize the different seepage fields in the matrix and fracture for tight gas reservoirs.The production parameters after CO_(2) dry fracturing were then optimized.Experimental results demonstrate that CO_(2) dry fracturing is more effective than slickwater fracturing,with a 9.2%increase in CH_(4) recovery.The increase in core permeability plays a positive role in improving CH_(4) production and CO_(2) flowback.The soaking process is mainly affected by CO_(2) diffusion,and the soaking time should be controlled within 12 h.Increasing the flowback pressure gradient results in a significant increase in both CH_(4) recovery and CO_(2) flowback efficiency.While,an increase in CO_(2) injection is not conducive to CH_(4) production and CO_(2) flowback.Based on the experimental and field data,the important factors affecting flowback and production were comprehensively and effectively discussed.The results show that permeability is the most important factor,followed by porosity and effective thickness.Considering flowback efficiency and the influence of proppant reflux,the injection volume should be the minimum volume that meets the requirements for generating fractures.The soaking time should be short which is 1 day in this study,and the optimal bottom hole flowback pressure should be set at 10 MPa.This study aims to improve the understanding of CO_(2) dry fracturing in tight gas reservoirs and provide valuable insights for optimizing the process parameters.展开更多
A design idea of fidelity sampling cylinder while drilling based on surface nitrogen precharging and supplemented by downhole pressurization was proposed, and the working mode and optimization method of sampling param...A design idea of fidelity sampling cylinder while drilling based on surface nitrogen precharging and supplemented by downhole pressurization was proposed, and the working mode and optimization method of sampling parameters were discussed. The nitrogen chamber in the sampling cylinder functions as an energy storage air cushion, which can supplement the pressure loss caused by temperature change in the sampling process to some extent. The downhole pressurization is to press the sample into the sample chamber as soon as possible, and further increase the pressure of sample to make up for the pressure that the nitrogen chamber cannot provide. Through the analysis of working mode of the sampling fidelity cylinder, the non-ideal gas state equation was used to deduce and calculate the optimal values of fidelity parameters such as pre-charged nitrogen pressure, downhole pressurization amount and sampling volume according to whether the bubble point pressure of the sampling fluid was known and on-site emergency sampling situation. Besides, the influences of ground temperature on fidelity parameters were analyzed, and corresponding correction methods were put forward. The research shows that the fidelity sampling cylinder while drilling can effectively improve the fidelity of the sample. When the formation fluid sample reaches the surface, it can basically ensure that the sample does not change in physical phase state and keeps the same chemical components in the underground formation.展开更多
As a useful alternative of Shewhart control chart, exponentially weighted moving average （EWMA） control chat has been applied widely to quality control, process monitoring, forecast, etc. In this paper, a method was...As a useful alternative of Shewhart control chart, exponentially weighted moving average （EWMA） control chat has been applied widely to quality control, process monitoring, forecast, etc. In this paper, a method was introduced for optimal design of EWMA and multivariate EWMA （MEWMA） control charts, in which the optimal parameter pair （ λ, k） or （ λ, h ） was searched by using the generalized regression neural network （GRNN）. The results indicate that the optimal parameter pair can be obtained effectively by the proposed strategy for a given in-control average running length （ARLo） and shift to detect under any conditions, removing the drawback of incompleteness existing in the tables that had been reported.展开更多
Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typica...Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.展开更多
The oil production of the multi-fractured horizontal wells(MFHWs) declines quickly in unconventional oil reservoirs due to the fast depletion of natural energy. Gas injection has been acknowledged as an effective meth...The oil production of the multi-fractured horizontal wells(MFHWs) declines quickly in unconventional oil reservoirs due to the fast depletion of natural energy. Gas injection has been acknowledged as an effective method to improve oil recovery factor from unconventional oil reservoirs. Hydrocarbon gas huff-n-puff becomes preferable when the CO_(2) source is limited. However, the impact of complex fracture networks and well interference on the EOR performance of multiple MFHWs is still unclear. The optimal gas huff-n-puff parameters are significant for enhancing oil recovery. This work aims to optimize the hydrocarbon gas injection and production parameters for multiple MFHWs with complex fracture networks in unconventional oil reservoirs. Firstly, the numerical model based on unstructured grids is developed to characterize the complex fracture networks and capture the dynamic fracture features.Secondly, the PVT phase behavior simulation was carried out to provide the fluid model for numerical simulation. Thirdly, the optimal parameters for hydrocarbon gas huff-n-puff were obtained. Finally, the dominant factors of hydrocarbon gas huff-n-puff under complex fracture networks are obtained by fuzzy mathematical method. Results reveal that the current pressure of hydrocarbon gas injection can achieve miscible displacement. The optimal injection and production parameters are obtained by single-factor analysis to analyze the effect of individual parameter. Gas injection time is the dominant factor of hydrocarbon gas huff-n-puff in unconventional oil reservoirs with complex fracture networks. This work can offer engineers guidance for hydrocarbon gas huff-n-puff of multiple MFHWs considering the complex fracture networks.展开更多
A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to impr...A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion resistance.Moreover,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element models.This work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element models.In this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element modeling.The Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element models.Because of the heat treatment,one plate has equiaxed microstructure and the other has bimodal microstructure.The convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion resistance.The bimodal target exhibits excellent deformation resistance.The response of bimodal microstructure to the shock wave may be more intense under explosive loading.The well-coordinated structure of the bimodal target enhances its resistance to deformation.展开更多
An optimization method of fracturing fluid volume strength was introduced taking well X-1 in Biyang Sag of Nanxiang Basin as an example.The characteristic curves of capillary pressure and relative permeability were ob...An optimization method of fracturing fluid volume strength was introduced taking well X-1 in Biyang Sag of Nanxiang Basin as an example.The characteristic curves of capillary pressure and relative permeability were obtained from history matching between forced imbibition experimental data and core-scale reservoir simulation results and taken into a large scale reservoir model to mimic the forced imbibition behavior during the well shut-in period after fracturing.The optimization of the stimulated reservoir volume(SRV)fracturing fluid volume strength should meet the requirements of estimated ultimate recovery(EUR),increased oil recovery by forced imbibition and enhancement of formation pressure and the fluid volume strength of fracturing fluid should be controlled around a critical value to avoid either insufficiency of imbibition displacement caused by insufficient fluid amount or increase of costs and potential formation damage caused by excessive fluid amount.Reservoir simulation results showed that SRV fracturing fluid volume strength positively correlated with single-well EUR and an optimal fluid volume strength existed,above which the single-well EUR increase rate kept decreasing.An optimized increase of SRV fracturing fluid volume and shut-in time would effectively increase the formation pressure and enhance well production.Field test results of well X-1 proved the practicality of established optimization method of SRV fracturing fluid volume strength on significant enhancement of shale oil well production.展开更多
The trajectory of the compact torus(CT)within a tokamak discharge is crucial to fueling.In this study,we developed a penetration model with a vacuum magnetic field region to accurately determine CT trajectories in tok...The trajectory of the compact torus(CT)within a tokamak discharge is crucial to fueling.In this study,we developed a penetration model with a vacuum magnetic field region to accurately determine CT trajectories in tokamak discharges.This model was used to calculate the trajectory and penetration parameters of CT injections by applying both perpendicular and tangential injection schemes in both HL-2A and ITER tokamaks.For perpendicular injection along the tokamak's major radius direction from the outboard,CTs with the same injection parameters exhibited a 0.08 reduction in relative penetration depth when injected into HL-2A and a 0.13reduction when injected into ITER geometry when considering the vacuum magnetic field region compared with cases where this region was not considered.In addition,we proposed an optimization method for determining the CT's initial injection velocity to accurately calculate the initial injection velocity of CTs for central fueling in tokamaks.Furthermore,this paper discusses schemes for the tangential injection of CT into tokamak discharges.The optimal injection angle and CT magnetic moment direction for injection into both HL-2A and ITER were determined through numerical simulations.Finally,the kinetic energy loss occurring when the CT penetrated the vacuum magnetic field region in ITER was reduced byΔEk=975.08 J by optimizing the injection angle for the CT injected into ITER.These results provide valuable insights for optimizing injection angles in fusion experiments.Our model closely represents actual experimental scenarios and can assist the design of CT parameters.展开更多
In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforatio...In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforation using ANSYS/LS-DYNA simulation technology. The combination of critical perforation parameters for double casing is obtained by studying the influencing factors of the jet-forming process,perforation depth, diameter, and stress changes of the inner and outer casing. The single-target perforation experiments under high-temperature and high-pressure(HTHP) conditions and ground full-scale ring target perforation tests are designed to verify the accuracy of numerical simulation results. The reduced factor is adopted as the quantitative measure of perforation depth and diameter for different types of perforation charge under different conditions. The results show that the perforation depth reduction increases with temperature and pressure, and the reduced factor is between 0.67 and 0.87 under HTHP conditions of 130℃/44 MPa and 137℃/60 MPa. Comparing the results of the numerical simulation and the full-scale test correction, the maximum error is less than 8.91%, and this numerical simulation has strong reliability. This research provides a basis for a reasonable range of double-cased perforation parameters and their optimal selection.展开更多
The influence of processing parameters on the precision of parts fabricated by fused deposition modeling （FDM） technology is studied based on a series of performed experiments. Processing parameters of FDM in terms ...The influence of processing parameters on the precision of parts fabricated by fused deposition modeling （FDM） technology is studied based on a series of performed experiments. Processing parameters of FDM in terms of wire-width compensation, extrusion velocity, filing velocity, and layer thickness are chosen as the control fac- tors. Robust design analysis and multi-index fuzzy comprehensive assessment method are used to obtain the opti- mal parameters. Results show that the influencing degrees of these four factors on the precision of as-processed parts are different. The optimizations of individual parameters and their combined effects are of the same impor- tance for a high precision manufacturing.展开更多
A new kind of process sintering process is dealt with manufacturing hammers of the hammer mill. Metallurgical products and single factor parameters are systematically studied in this paper. One element experiments a...A new kind of process sintering process is dealt with manufacturing hammers of the hammer mill. Metallurgical products and single factor parameters are systematically studied in this paper. One element experiments and orthogonal design experiments are carried out to achieve optimized parameters. Experimental results provide important theoretical guidance and experimental data for its further application.展开更多
This paper deals with Polyurethane Foam Polishing Tool (PFPT), which has three dimensional softness and are adapted to polishing sophisticated curved surfaces. The manufacturing technology, the equilibrium theory of ...This paper deals with Polyurethane Foam Polishing Tool (PFPT), which has three dimensional softness and are adapted to polishing sophisticated curved surfaces. The manufacturing technology, the equilibrium theory of matter and energy have been discussed and the PFPT is produced successfully at our laboratory. After investigating their properties, the effective factors to the behavior of the PFPT are studied. The microcosmic construction of the PFPT have been observed by sweep electron microscope(SEM) and the polishing mechanism studied. A great deal of experiments have been carried out to optimize the manufacturing parameters.展开更多
By the study of extended range guided munitions (ERGM) trajectory characteristics, ERGM free-flight and glide trajectory characteristics are revealed and illustrated. On the basis of free-flight trajectory mathematica...By the study of extended range guided munitions (ERGM) trajectory characteristics, ERGM free-flight and glide trajectory characteristics are revealed and illustrated. On the basis of free-flight trajectory mathematical model, a two-parameter optimization problem of quadrant elevation and rocket ignition time is studied. Using the atmosphere mathematical model, the best glide-starting point of the downward trajectory is determined. With an optimal control mathematical model, the ERGM optimal glide trajectory is obtained.展开更多
The adjustable parameters in the popular conductor-like screening model for real solvents(COSMO-RS)within the Amsterdam density functional(ADF)framework have been re-optimized to fit for the systems containing ionic l...The adjustable parameters in the popular conductor-like screening model for real solvents(COSMO-RS)within the Amsterdam density functional(ADF)framework have been re-optimized to fit for the systems containing ionic liquids(ILs).To get the optimal values of misfit energy constant a^0,hydrogen bond coefficient c_(hb)and effective contact surface area of a segment a_(eff),2283 activity coefficient data points at infinite dilution and 1433 CO_2 solubility data points exhaustively collected from references were used as training set.The average relative deviations(ARDs)of activity coefficients at infinite dilution and CO_2 solubility between experimental data and predicted values are 32.22%and17.61%,respectively,both of which are significantly lower than the original COSMO-RS versions.Predictions for other activity coefficients of solutes in ILs,solubility data of CO_2 in pure ILs and the binary mixtures of ILs at either high or low temperatures,and vapor–liquid equilibrium(VLE)for binary systems involving ILs have also been performed to demonstrate the validity of the parameterization of COSMO-RS model for ILs.The results showed that the predicted results by COSMO-RS model with the new optimized parameters are in much better agreement with experimental data than those by the original versions over a wide temperature and pressure range.The COSMO-RS model for ILs presented in this work improves the prediction accuracy of thermodynamic properties for the systems containing ILs,which is always highly desirable for general chemical engineers.展开更多
Surface modification,as a promising approach to improve biocompatibility of biomaterials,has captured extensive close attention among many researchers.Here,micro-milling technology was used in constructing pyramid mic...Surface modification,as a promising approach to improve biocompatibility of biomaterials,has captured extensive close attention among many researchers.Here,micro-milling technology was used in constructing pyramid micro-structures on the surface of Ti-6Al-4Vimplant.Cutting parameters,including spindle speed,feed rate and depth of cut,were optimized to control the generation of burrs.In addition,low melting point alloy was selected to extend the boundary of the workpiece as supporting material to prevent the generation of top burrs.The surface topographies were characterized using scanning electron microscope and laser scanning microscope.Results showed that the dimension of burrs decreased with the decrease of depth of cut,and the size of burrs decreased with the increase of feed rate.Moreover,burrs nearly not appeared on both sides of the micro-grooves machined with low melting point alloy(LMPA)coating.Pyramid micro-structure on the workpiece surface was built successfully by combining optimized cutting parameters(S=35kr/min,Vf=60mm/min,ap=5μm)and LMPA coating.展开更多
文摘Aim To obtain an optimizing range of the main configuration parameters of double swirls combustion system (DSCS) Methods To analyze the influence of DS combustion cham-ber configuration parameters on fuel spray and mixing by means of the fuel jet developmentperiphery charts obtained by the high speed photography with a modeling test device deve-loped by authors,and to examine it by the tests on a single cylinder diesel engine.Resultsand Conclusion The mixing process can be divided into four phases.The optimizing range of the ration of the inner chamber diameter to the cylinder bore,d2/D,is 0.4-0.7; and the outerchamber diameter,d1 the height of the circular ridge to the piston top face,h1,the radius of outer/inner chamber circle,R1,R2 ,the max depth of outer/inner chamber bowl,H1,H2,etc. are also important
文摘An algorithm named InterOpt for optimizing operational parameters is proposed based on interpretable machine learning,and is demonstrated via optimization of shale gas development.InterOpt consists of three parts:a neural network is used to construct an emulator of the actual drilling and hydraulic fracturing process in the vector space(i.e.,virtual environment);:the Sharpley value method in inter-pretable machine learning is applied to analyzing the impact of geological and operational parameters in each well(i.e.,single well feature impact analysis):and ensemble randomized maximum likelihood(EnRML)is conducted to optimize the operational parameters to comprehensively improve the efficiency of shale gas development and reduce the average cost.In the experiment,InterOpt provides different drilling and fracturing plans for each well according to its specific geological conditions,and finally achieves an average cost reduction of 9.7%for a case study with 104 wells.
基金The financial support from the Australian Government as Part of the Asia-Pacific Partnership on Clean Development and Climate,and the National Natural Science Foundation of China (Nos. 51074156 and 51274196)
文摘Sampling ports were firstly drilled on a ZGM95 coal mill in the power plant in China, and the coal samples from various points in the pulverizer were collected under the different operation conditions. The prop- erty of the sampling material from the mill was analyzed, applying the float-sink test, size distribution analysis, proximate analysis and so on. It was indicated that the ＋250 I^m fraction in the pulverized fuel accounted for only 0.02%, while it was 83.2% in the new feed. The circulating ratio and coal flow in the separator and the cone zone were calculated using the mass balance of the circulating load. So, the cir- culating ratio in the separator of the pulverizer was between 8 and 13, and the circulating ratio, the feed flow of separator and cone zone all raised with the increase of the air volume. Furthermore, the parameters of the separation functions were obtained based on the fitting method. It was shown that the mean value of the shape factor B was 0.7617, and the parameter D which is the particle size at 50% cumulative yield in the separator almost kept unchanged.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074282 and 11474320
文摘We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experiment. Saturation broadening spectra of the ground state hyperfine transition of trapped 199Hg＋ ions are measured and analyzed. The value of the optimal microwave power is obtained by using the proposed method and is verified. Rabi oscillations decay spectra of trapped 199Hg＋ ions are observed and the optimal microwave irradiation time for the maximum transition signal intensity is determined. This work will help to improve the short-term frequency stability of the mercury ion microwave frequency standard.
基金supported by the Open Fund for State Environmental Protection Key Laboratory of Synergetic Control and Joint Remediation for Soil&Water Pollution(No.GHBK-2020-006)National Natural Science Foundation of China(No.21876070)。
文摘In the present work,pulsed gas–liquid hybrid discharge plasma coupled with graphene/Cd S catalyst was evaluated to eliminate bisphenol A(BPA)in wastewater.The optimization of a series of process parameters was performed in terms of BPA degradation performance.The experimental results demonstrated that nearly 90%of BPA(20 mg l^(-1))in the synthetic wastewater(p H=7.5,σ=10μS m^(-1))was degraded by the plasma catalytic system over 0.2 g l^(-1)graphene/Cd S at 19k V with a 4 l min^(-1)air flow rate and 10 mm electrode gap within 60 min.The BPA removal rate increased with increasing the discharge voltage and decreasing the initial BPA concentration or solution conductivity.Nevertheless,either too high or too low an air flow rate,electrode gap,catalyst dosage or initial solution p H would lead to a decrease in BPA degradation.Moreover,optical emission spectroscopy was used to gain information on short-lived reactive species formed from the pulsed gas–liquid hybrid discharge plasma system.The results indicated the existence of several highly oxidative free radicals such as·O and·OH.Finally,the activation pathway of O_(3)on the catalyst surface was analyzed by density functional theory.
基金support from the National Natural Science Foundation of China(No.51904324,No.51974348)the Prospective Basic Major Science and Technology Projects for the 14th Five Year Plan(No.2021DJ2202).
文摘CO_(2) dry fracturing is a promising alternative method to water fracturing in tight gas reservoirs,especially in water-scarce areas such as the Loess Plateau.The CO_(2) flowback efficiency is a critical factor that affects the final gas production effect.However,there have been few studies focusing on the flowback characteristics after CO_(2) dry fracturing.In this study,an extensive core-to-field scale study was conducted to investigate CO_(2) flowback characteristics and CH_(4) production behavior.Firstly,to investigate the impact of core properties and production conditions on CO_(2) flowback,a series of laboratory experiments at the core scale were conducted.Then,the key factors affecting the flowback were analyzed using the grey correlation method based on field data.Finally,taking the construction parameters of Well S60 as an example,a dual-permeability model was used to characterize the different seepage fields in the matrix and fracture for tight gas reservoirs.The production parameters after CO_(2) dry fracturing were then optimized.Experimental results demonstrate that CO_(2) dry fracturing is more effective than slickwater fracturing,with a 9.2%increase in CH_(4) recovery.The increase in core permeability plays a positive role in improving CH_(4) production and CO_(2) flowback.The soaking process is mainly affected by CO_(2) diffusion,and the soaking time should be controlled within 12 h.Increasing the flowback pressure gradient results in a significant increase in both CH_(4) recovery and CO_(2) flowback efficiency.While,an increase in CO_(2) injection is not conducive to CH_(4) production and CO_(2) flowback.Based on the experimental and field data,the important factors affecting flowback and production were comprehensively and effectively discussed.The results show that permeability is the most important factor,followed by porosity and effective thickness.Considering flowback efficiency and the influence of proppant reflux,the injection volume should be the minimum volume that meets the requirements for generating fractures.The soaking time should be short which is 1 day in this study,and the optimal bottom hole flowback pressure should be set at 10 MPa.This study aims to improve the understanding of CO_(2) dry fracturing in tight gas reservoirs and provide valuable insights for optimizing the process parameters.
基金Supported by the Sinopec Major Science and Technology Project (JPE19007)。
文摘A design idea of fidelity sampling cylinder while drilling based on surface nitrogen precharging and supplemented by downhole pressurization was proposed, and the working mode and optimization method of sampling parameters were discussed. The nitrogen chamber in the sampling cylinder functions as an energy storage air cushion, which can supplement the pressure loss caused by temperature change in the sampling process to some extent. The downhole pressurization is to press the sample into the sample chamber as soon as possible, and further increase the pressure of sample to make up for the pressure that the nitrogen chamber cannot provide. Through the analysis of working mode of the sampling fidelity cylinder, the non-ideal gas state equation was used to deduce and calculate the optimal values of fidelity parameters such as pre-charged nitrogen pressure, downhole pressurization amount and sampling volume according to whether the bubble point pressure of the sampling fluid was known and on-site emergency sampling situation. Besides, the influences of ground temperature on fidelity parameters were analyzed, and corresponding correction methods were put forward. The research shows that the fidelity sampling cylinder while drilling can effectively improve the fidelity of the sample. When the formation fluid sample reaches the surface, it can basically ensure that the sample does not change in physical phase state and keeps the same chemical components in the underground formation.
基金Funded by the National Key Technologies R&D Programs of China (No.2002BA105C)
文摘As a useful alternative of Shewhart control chart, exponentially weighted moving average （EWMA） control chat has been applied widely to quality control, process monitoring, forecast, etc. In this paper, a method was introduced for optimal design of EWMA and multivariate EWMA （MEWMA） control charts, in which the optimal parameter pair （ λ, k） or （ λ, h ） was searched by using the generalized regression neural network （GRNN）. The results indicate that the optimal parameter pair can be obtained effectively by the proposed strategy for a given in-control average running length （ARLo） and shift to detect under any conditions, removing the drawback of incompleteness existing in the tables that had been reported.
基金supported by the National Natural Science Foundation of China Joint Fund Project (Grant/Award Number: U20B6003)National Natural Science Foundation of China (Grant/Award Number: 52304054)。
文摘Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.
基金funded by the National Natural Science Foundation of China(No.51974268)Open Fund of Key Laboratory of Ministry of Education for Improving Oil and Gas Recovery(NEPUEOR-2022-03)Research and Innovation Fund for Graduate Students of Southwest Petroleum University(No.2022KYCX005)。
文摘The oil production of the multi-fractured horizontal wells(MFHWs) declines quickly in unconventional oil reservoirs due to the fast depletion of natural energy. Gas injection has been acknowledged as an effective method to improve oil recovery factor from unconventional oil reservoirs. Hydrocarbon gas huff-n-puff becomes preferable when the CO_(2) source is limited. However, the impact of complex fracture networks and well interference on the EOR performance of multiple MFHWs is still unclear. The optimal gas huff-n-puff parameters are significant for enhancing oil recovery. This work aims to optimize the hydrocarbon gas injection and production parameters for multiple MFHWs with complex fracture networks in unconventional oil reservoirs. Firstly, the numerical model based on unstructured grids is developed to characterize the complex fracture networks and capture the dynamic fracture features.Secondly, the PVT phase behavior simulation was carried out to provide the fluid model for numerical simulation. Thirdly, the optimal parameters for hydrocarbon gas huff-n-puff were obtained. Finally, the dominant factors of hydrocarbon gas huff-n-puff under complex fracture networks are obtained by fuzzy mathematical method. Results reveal that the current pressure of hydrocarbon gas injection can achieve miscible displacement. The optimal injection and production parameters are obtained by single-factor analysis to analyze the effect of individual parameter. Gas injection time is the dominant factor of hydrocarbon gas huff-n-puff in unconventional oil reservoirs with complex fracture networks. This work can offer engineers guidance for hydrocarbon gas huff-n-puff of multiple MFHWs considering the complex fracture networks.
基金National Key Laboratory of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2022-4)to provide fund for conducting experiments。
文摘A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion resistance.Moreover,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element models.This work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element models.In this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element modeling.The Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element models.Because of the heat treatment,one plate has equiaxed microstructure and the other has bimodal microstructure.The convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion resistance.The bimodal target exhibits excellent deformation resistance.The response of bimodal microstructure to the shock wave may be more intense under explosive loading.The well-coordinated structure of the bimodal target enhances its resistance to deformation.
文摘An optimization method of fracturing fluid volume strength was introduced taking well X-1 in Biyang Sag of Nanxiang Basin as an example.The characteristic curves of capillary pressure and relative permeability were obtained from history matching between forced imbibition experimental data and core-scale reservoir simulation results and taken into a large scale reservoir model to mimic the forced imbibition behavior during the well shut-in period after fracturing.The optimization of the stimulated reservoir volume(SRV)fracturing fluid volume strength should meet the requirements of estimated ultimate recovery(EUR),increased oil recovery by forced imbibition and enhancement of formation pressure and the fluid volume strength of fracturing fluid should be controlled around a critical value to avoid either insufficiency of imbibition displacement caused by insufficient fluid amount or increase of costs and potential formation damage caused by excessive fluid amount.Reservoir simulation results showed that SRV fracturing fluid volume strength positively correlated with single-well EUR and an optimal fluid volume strength existed,above which the single-well EUR increase rate kept decreasing.An optimized increase of SRV fracturing fluid volume and shut-in time would effectively increase the formation pressure and enhance well production.Field test results of well X-1 proved the practicality of established optimization method of SRV fracturing fluid volume strength on significant enhancement of shale oil well production.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2022YFE03100004 and 2022YFE03060003)National Natural Science Foundation of China(Nos.12375226,12175227 and 11875255)the China Postdoctoral Science Foundation(No.2022M723066).
文摘The trajectory of the compact torus(CT)within a tokamak discharge is crucial to fueling.In this study,we developed a penetration model with a vacuum magnetic field region to accurately determine CT trajectories in tokamak discharges.This model was used to calculate the trajectory and penetration parameters of CT injections by applying both perpendicular and tangential injection schemes in both HL-2A and ITER tokamaks.For perpendicular injection along the tokamak's major radius direction from the outboard,CTs with the same injection parameters exhibited a 0.08 reduction in relative penetration depth when injected into HL-2A and a 0.13reduction when injected into ITER geometry when considering the vacuum magnetic field region compared with cases where this region was not considered.In addition,we proposed an optimization method for determining the CT's initial injection velocity to accurately calculate the initial injection velocity of CTs for central fueling in tokamaks.Furthermore,this paper discusses schemes for the tangential injection of CT into tokamak discharges.The optimal injection angle and CT magnetic moment direction for injection into both HL-2A and ITER were determined through numerical simulations.Finally,the kinetic energy loss occurring when the CT penetrated the vacuum magnetic field region in ITER was reduced byΔEk=975.08 J by optimizing the injection angle for the CT injected into ITER.These results provide valuable insights for optimizing injection angles in fusion experiments.Our model closely represents actual experimental scenarios and can assist the design of CT parameters.
基金the support of the Foundation of Natural Science Foundation of Shaanxi Province, Grant/ Award nos. 2023-JC-YB-361National Natural Science Foundation (Number 52104033)。
文摘In order to ensure the penetrability of double-cased perforation in offshore oil and gas fields and to maximize the capacity of perforation completion, This study establishes a dynamic model of double-cased perforation using ANSYS/LS-DYNA simulation technology. The combination of critical perforation parameters for double casing is obtained by studying the influencing factors of the jet-forming process,perforation depth, diameter, and stress changes of the inner and outer casing. The single-target perforation experiments under high-temperature and high-pressure(HTHP) conditions and ground full-scale ring target perforation tests are designed to verify the accuracy of numerical simulation results. The reduced factor is adopted as the quantitative measure of perforation depth and diameter for different types of perforation charge under different conditions. The results show that the perforation depth reduction increases with temperature and pressure, and the reduced factor is between 0.67 and 0.87 under HTHP conditions of 130℃/44 MPa and 137℃/60 MPa. Comparing the results of the numerical simulation and the full-scale test correction, the maximum error is less than 8.91%, and this numerical simulation has strong reliability. This research provides a basis for a reasonable range of double-cased perforation parameters and their optimal selection.
基金Supported by the Science and Technology Support Key Project of 12th Five-Year of China(2011BAD20B00-4)~~
文摘The influence of processing parameters on the precision of parts fabricated by fused deposition modeling （FDM） technology is studied based on a series of performed experiments. Processing parameters of FDM in terms of wire-width compensation, extrusion velocity, filing velocity, and layer thickness are chosen as the control fac- tors. Robust design analysis and multi-index fuzzy comprehensive assessment method are used to obtain the opti- mal parameters. Results show that the influencing degrees of these four factors on the precision of as-processed parts are different. The optimizations of individual parameters and their combined effects are of the same impor- tance for a high precision manufacturing.
文摘A new kind of process sintering process is dealt with manufacturing hammers of the hammer mill. Metallurgical products and single factor parameters are systematically studied in this paper. One element experiments and orthogonal design experiments are carried out to achieve optimized parameters. Experimental results provide important theoretical guidance and experimental data for its further application.
文摘This paper deals with Polyurethane Foam Polishing Tool (PFPT), which has three dimensional softness and are adapted to polishing sophisticated curved surfaces. The manufacturing technology, the equilibrium theory of matter and energy have been discussed and the PFPT is produced successfully at our laboratory. After investigating their properties, the effective factors to the behavior of the PFPT are studied. The microcosmic construction of the PFPT have been observed by sweep electron microscope(SEM) and the polishing mechanism studied. A great deal of experiments have been carried out to optimize the manufacturing parameters.
文摘By the study of extended range guided munitions (ERGM) trajectory characteristics, ERGM free-flight and glide trajectory characteristics are revealed and illustrated. On the basis of free-flight trajectory mathematical model, a two-parameter optimization problem of quadrant elevation and rocket ignition time is studied. Using the atmosphere mathematical model, the best glide-starting point of the downward trajectory is determined. With an optimal control mathematical model, the ERGM optimal glide trajectory is obtained.
基金financially supported by the National Natural Science Foundation of China under Grants (Nos. 21476009, 21406007 and U1462104)
文摘The adjustable parameters in the popular conductor-like screening model for real solvents(COSMO-RS)within the Amsterdam density functional(ADF)framework have been re-optimized to fit for the systems containing ionic liquids(ILs).To get the optimal values of misfit energy constant a^0,hydrogen bond coefficient c_(hb)and effective contact surface area of a segment a_(eff),2283 activity coefficient data points at infinite dilution and 1433 CO_2 solubility data points exhaustively collected from references were used as training set.The average relative deviations(ARDs)of activity coefficients at infinite dilution and CO_2 solubility between experimental data and predicted values are 32.22%and17.61%,respectively,both of which are significantly lower than the original COSMO-RS versions.Predictions for other activity coefficients of solutes in ILs,solubility data of CO_2 in pure ILs and the binary mixtures of ILs at either high or low temperatures,and vapor–liquid equilibrium(VLE)for binary systems involving ILs have also been performed to demonstrate the validity of the parameterization of COSMO-RS model for ILs.The results showed that the predicted results by COSMO-RS model with the new optimized parameters are in much better agreement with experimental data than those by the original versions over a wide temperature and pressure range.The COSMO-RS model for ILs presented in this work improves the prediction accuracy of thermodynamic properties for the systems containing ILs,which is always highly desirable for general chemical engineers.
基金supported by the National Natural Science Foundations of China(Nos.51175306,51425503)the Tai Shan Scholar Foundation,the Fundamental Research Funds for the Central Universities(No.2014JC020)the Opening fund of State Key Laboratory of Nonlinear Mechanics
文摘Surface modification,as a promising approach to improve biocompatibility of biomaterials,has captured extensive close attention among many researchers.Here,micro-milling technology was used in constructing pyramid micro-structures on the surface of Ti-6Al-4Vimplant.Cutting parameters,including spindle speed,feed rate and depth of cut,were optimized to control the generation of burrs.In addition,low melting point alloy was selected to extend the boundary of the workpiece as supporting material to prevent the generation of top burrs.The surface topographies were characterized using scanning electron microscope and laser scanning microscope.Results showed that the dimension of burrs decreased with the decrease of depth of cut,and the size of burrs decreased with the increase of feed rate.Moreover,burrs nearly not appeared on both sides of the micro-grooves machined with low melting point alloy(LMPA)coating.Pyramid micro-structure on the workpiece surface was built successfully by combining optimized cutting parameters(S=35kr/min,Vf=60mm/min,ap=5μm)and LMPA coating.
