Coralline soils,specialized materials found extensively in the South China Sea,are playing an increasingly vital role in engineering projects.However,like most terrigenous soils,fine-grained coral soil is prone to shr...Coralline soils,specialized materials found extensively in the South China Sea,are playing an increasingly vital role in engineering projects.However,like most terrigenous soils,fine-grained coral soil is prone to shrinkage and cracking,which can significantly affect its engineering properties and ultimately jeopardize engineering safety.This paper presents a desiccation cracking test of fine-grained coral soil,with a particular focus on the thickness effect.The study involved measuring the water content and recording the evolution of desiccation cracking.Advanced image processing technology is employed to analyze the variations in crack parameters,clod parameters,fractal dimensions,frequency distributions,and desiccation cracking propagation velocities of fine-grained coral soil.Furthermore,the dynamic evolution of desiccation cracking under the influence of layer thickness is analyzed.A comprehensive crack evolution model is proposed,encompassing both top-down and bottom-up crack propagation,as well as internal tensile cracking.This work introduces novel metrics for the propagation velocity of the total crack area,the characteristic propagation velocities of desiccation cracks,and the acceleration of crack propagation.Through data fitting,theoretical formulas for soil water evaporation,propagation velocities of desiccation cracks,and crack propagation acceleration are derived,laying a foundation for future soil cracking theories.展开更多
This study aims to elucidate the dynamic evolution mechanism of the fracturing fracture system during the exploration and development of complex oil and gas reservoirs.By integrating methods of rock mechanical testing...This study aims to elucidate the dynamic evolution mechanism of the fracturing fracture system during the exploration and development of complex oil and gas reservoirs.By integrating methods of rock mechanical testing,logging calculation,and seismic inversion technology,we obtained the current insitu stress characteristics of a single well and rock mechanical parameters.Simultaneously,significant controlling factors of rock mechanical properties were analyzed.Subsequently,by coupling hydraulic fracturing physical experiments with finite element numerical simulation,three different fracturing models were configured:single-cluster,double-cluster,and triple-cluster perforations.Combined with acoustic emission technology,the fracture initiation mode and evolution characteristics during the loading process were determined.The results indicate the following findings:(1)The extension direction and length of the fracture are significantly controlled by the direction of the maximum horizontal principal stress.(2)Areas with poor cementation and compactness exhibit complex fracture morphology,prone to generating network fractures.(3)The interlayer development of fracturing fractures is controlled by the strata occurrence.(4)Increasing the displacement of fracturing fluid enlarges the fracturing fracture length and height.This research provides theoretical support and effective guidance for hydraulic fracturing design in tight oil and gas reservoirs.展开更多
Rock blocks sliding along discontinuities can cause serious disasters,such as landslides,earthquakes,or rock bursts.The shear rate-dependent behavior is a typical time-dependent behavior of a rock discontinuity,and it...Rock blocks sliding along discontinuities can cause serious disasters,such as landslides,earthquakes,or rock bursts.The shear rate-dependent behavior is a typical time-dependent behavior of a rock discontinuity,and it is closely related to the stability of a rock block.To further study the shear rate-dependent behavior of rock discontinuities,shear tests with alternating shear rates(SASRs)were conducted on rock discontinuities with various surface morphologies.The dynamic evolution of the shear rate dependency was studied in detail based on the shear test results,and three stages were identified with respect to the shear stress and shear deformation states.The test results revealed that dynamic changes in shear stiffness and the energy storage abilities of the rock discontinuities occurred in relation to the shear rate-dependent behavior of crack growth,which increased with an increase in normal stress and/or the joint roughness coefficient.The stage of decreasing shear stiffness corresponded to a stage of noticeable shear rate-dependency,and the shear rate was found to have no influence on the initial crack stress.展开更多
It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social ...It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.展开更多
To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the...To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the regional differences and evolutionary trends in the development quality of China’power sector has a high value to inspire the next improvement direction toward how to integrate regional power recourses to an overall optimization level.Motived by this purpose,this paper uses the entropy method to evaluate the com‐prehensive and subsystem indices of the development quality of the power industry,and reveals their re‐gional differences and evolutionary trends with the help of the Dagum Gini coefficient and Kernel density es‐timation methods.The findings show that:There are obvious regional differences in the development quality of China’s power industry,and the differences are steadily declining in all regions except the West.Regional differences are mainly derived from inter-regional differences,with the largest inter-regional differences in the East-Northeast region.Intra-regional differences show a distribution pattern of East>West>North‐east>Center.展开更多
Following a new train of thinking, this paper has explored first the potential information in the ground resistivitydata observed by the existing geoelectric observation system, investigated and proposed a new dimensi...Following a new train of thinking, this paper has explored first the potential information in the ground resistivitydata observed by the existing geoelectric observation system, investigated and proposed a new dimensionlessgeoelectric precursor factor, the degree of ground resistivity anisotropy, S, and studied the characteristics of dynamic evolution pattern of S during the seismogenic process. The results show that, during the seismogenic process, the degree of ground resistivity anisotropy (S) displays h process of 'normal' → 'abnormal strengthening(amplitude, range)' → 'abnormal weakening'→ 'earthquake occurrence'→ 'normal'. The earthquake wouldoccur at the time when the S value has entered the late stage of strengthening and turns to weaken and in the gradient belt on the margin ofS anomaly region. The dynamic evolution pattern ofS reflects the changes of the tectonicstress field during the seismogenic process. Therefore, it would be possible to trace the process of earthquake generation and occurrence from the dynamic evolution pattern ofS so as to service eaJ'thquake prediction.展开更多
Empirical data show that most of the degree distribution of airline networks assume a double power law. In this work, firstly, we assume cities as sites, flight between two cities as an edge between two sites, and bui...Empirical data show that most of the degree distribution of airline networks assume a double power law. In this work, firstly, we assume cities as sites, flight between two cities as an edge between two sites, and build a dynamic evolution model for airline networks by improving the BA model, in which the conception of attractiveness plays a decisive role in the course of evolution of the networks. To this end, we discuss whether the attractiveness depends on the site label s or not separately, finally we obtain analytic degree distribution. As a result, if the attractiveness of a site is independent of the degree distribution of sites, which will follow the double power law, otherwise, it will be scale-free. Moreover, degree distribution depends on the parameters of the models, and some parameters aye more sensitive than others.展开更多
As the ability of a single agent is limited while information and resources in multi-agent systems are distributed, cooperation is necessary for agents to accomplish a complex task. In the open and changeable environm...As the ability of a single agent is limited while information and resources in multi-agent systems are distributed, cooperation is necessary for agents to accomplish a complex task. In the open and changeable environment on the Internet, it is of great significance to research a system flexible and capable in dynamic evolution that can find a collaboration method for agents which can be used in dynamic evolution process. With such a method, agents accomplish tasks for an overall target and at the same time, the collaborative relationship of agents can be adjusted with the change of environment. A method of task decomposition and collaboration of agents by improved contract net protocol is introduced. Finally, analysis on the result of the experiments is performed to verify the improved contract net protocol can greatly increase the efficiency of communication and collaboration in multi-agent system.展开更多
The electrochemical nitrate reduction reaction(eNO_(3)^(-)RR)is considered an effective approach for converting nitrate-containing wastewater to ammonia.The adsorption and activation of NO_(3)^(-)is the critical step ...The electrochemical nitrate reduction reaction(eNO_(3)^(-)RR)is considered an effective approach for converting nitrate-containing wastewater to ammonia.The adsorption and activation of NO_(3)^(-)is the critical step for many materials and the high energy barrier inhibits the continuation of the reduction reaction.The Co nanoparticles encapsulated in the carbon layer we prepared spontaneously react with NO_(3)^(-)and the resulting Co^(2+)is then reduced by electroreduction to Co^(0),which circulates continuously.This resulted in overcoming the energy input required for NO_(3)^(-)adsorption and conversion,thereby increasing the catalytic activity.At the same time,the morphology of the catalyst reconstructed from a dodecahedron to an interwoven nanosheet structure and the increased surface area also gives it better properties.The obtained Co(OH)_(2)@Co-N-C has an excellent eNO_(3)^(-)RR of 2774.7μg·h^(-1)·cm^(-2)with a Faraday efficiency of 81.4%in neutral solution.At the same time,the material-modified electrode can run stably for more than 100 h.Our work provides a new idea for the design of Co-based catalysts for eNO_(3)^(-)RR.展开更多
Agricultural new quality productive forces are the key foundation for realizing high-quality agricultural development.This study constructs the evaluation indicator system of agricultural new quality productive forces...Agricultural new quality productive forces are the key foundation for realizing high-quality agricultural development.This study constructs the evaluation indicator system of agricultural new quality productive forces(ANQPFs)from three dimensions:agricultural laborers,agricultural labor objects,and agricultural labor resources.The equal weight method,entropy method,and CRITIC method are comprehensively applied to measure ANQPFs in China from 2011 to 2021.The Dagum's Gini coefficient,variance decomposition,kernel density estimation,Markov chain,and obstacle degree model are used to analyze regional differences,structural differences,dynamic evolution,and obstacle factors of ANQPFs.The findings show that:(1)There is an upward trend in ANQPFs in the national and the three major regions during the study period,while there are significant differences in ANQPFs by regions,which are characterized by a decreasing distribution from the east to the central,and then to the west.(2)The overall differences in ANQPFs have tended to widen,with inter-regional differences being the main source.(3)Agricultural labor object differences and agricultural labor resource differences are the main structural sources of ANQPFs development differences in China,with agricultural labor resource differences replacing agricultural labor object differences as the top source of ANQPFs differences after 2016.(4)The ANQPFs of the national and three regions show the distribution dynamics of"overall increase,absolute differences widen",and there is the phenomenon of"club convergence"in ANQPFs.(5)The number of Taobao villages,rural entrepreneurial activities,the number of agricultural science and technology patents per capita,and expenditure on agricultural science and technology activities are the main factors obstructing the development of ANQPFs.展开更多
Rapid climate change and human disturbance have caused serious damage and shrinkage of the wetlands in the Mongolian Plateau,posing severe challenges to environmental development.Based on remote sensing images and DEM...Rapid climate change and human disturbance have caused serious damage and shrinkage of the wetlands in the Mongolian Plateau,posing severe challenges to environmental development.Based on remote sensing images and DEM data,this study established a series of datasets for lakeside wetlands in the Mongolian Plateau in 2000,2010 and 2020,and investigated the dynamic evolution of lakeside wetlands in the Mongolian Plateau through spatial and temporal analyses.The results showed that in 2000,there were 564 lakes(>1 km^(2))in the Mongolian Plateau,with a total area of about 55216.47 km^(2).Compared with 2000,the area of lakes in 2010 was significantly reduced,and there was a significant increase in the number of woody marshes and a reduction in the number of herbaceous marshes.In 2020,the lakes in the central part of the Mongolian Plateau were smaller than in 2010.The areas of lakes in the western,southern and eastern regions were increasing,and the areas of herbaceous swamps,woody marshes and meadows were increasing overall.Lakes,bare land and saline-alkali land decreased overall.The degree of salinization was reduced over the study period.There was a significant correlation between the Adaptive Palmer Drought Index(scPDSI)and lake area.In the past two decades,the climatic factors and human activities of the Mongolian Plateau have profoundly affected the evolution of the lakeside wetlands.We should prioritize the protection of lakes and wetland resources in order to achieve the dynamic balance of wetland ecology.展开更多
Lake wetlands play a crucial role as global carbon sinks,significantly contributing to carbon storage and ecological balance.This study estimates the quarterly carbon storage in the Dongting Lake wetland for the years...Lake wetlands play a crucial role as global carbon sinks,significantly contributing to carbon storage and ecological balance.This study estimates the quarterly carbon storage in the Dongting Lake wetland for the years 2010,2015,and 2020,using MODIS remote sensing imagery and the InVEST model.A Structural Equation Model(SEM)was then employed to analyze the driving factors behind changes in carbon storage.Results show that intra-annual carbon storage increases and then decreases,with maximum level in the third quarter(average of 34.242 Tg)and a minimum one in the first quarter(average of 21.435 Tg).From 2010 to 2020,inter-annual carbon storage variations initially exhibited an increasing trend before decreasing,with the peak annual average carbon storage reaching 32.230 Tg in 2015.Notably,the coefficient of variation for intra-annual carbon storage increased from 8.5%in 2010 to 25.8%in 2020.Key driving factors that influence carbon storage changes include surface solar radiation,temperature,and water level,with carbon storage positively correlated with surface solar radiation and temperature,and negatively correlated with water level.These findings reveal the spatiotemporal evolution characteristics of carbon storage in the Dongting Lake wetland,offering scientific guidance for wetland conservation and regional climate adaptation policies.展开更多
Poly(phthalazinone ether sulfone ketone)(PPESK)is a new-generation high-performance thermoplastic resin that exhibits excellent thermal stability and mechanical properties.However,its damage and failure mechanisms und...Poly(phthalazinone ether sulfone ketone)(PPESK)is a new-generation high-performance thermoplastic resin that exhibits excellent thermal stability and mechanical properties.However,its damage and failure mechanisms under high-temperature and high-strain-rate coupling conditions remain unclear,significantly limiting the engineering applications of PPESK-based composites in extreme environments such as aerospace.To address this issue,in this study,a temperature-controlled split Hopkinson pressure bar experimental platform was developed for dynamic tensile/compressive loading scenarios.Combined with scanning electron microscopy and molecular dynamics simulations,the thermomechanical behavior and failure mechanisms of PPESK were systematically investigated over the temperature range of 293-473 K.The study revealed a novel"dynamic hysteresis brittle behavior"and its underlying"segmental activation±response lag antagonistic mechanism".The results showed that the strain-rate-induced response lag of polymer chain segments significantly weakened the viscous dissipation capacity activated by thermal energy at elevated temperatures.Although high-strain-rate conditions led to notable enhancement in the dynamic strength of the material(with an increase of 8%-233%,reaching 130%-330%at elevated temperatures),the fracture surface morphology tended to become smoother,and brittle fracture characteristics became more pronounced.Based on these findings,a temperature±strain rate hysteresis antagonistic function was constructed,which effectively captured the competitive relationship between temperature-driven relaxation behavior and strain-rateinduced hysteresis in thermoplastic resins.A multiscale damage evolution constitutive model with temperature±rate coupling was subsequently established and numerically implemented via the VUMAT user subroutine.This study not only unveils the nonlinear damage mechanisms of PPESK under combined service temperatures and dynamic/static loading conditions,but also provides a strong theoretical foundation and engineering guidance for the constitutive modeling and parametric design of thermoplastic resin-based materials.展开更多
Plant genomes harbor dozens to hundreds of nucleotide-binding site-leucine-rich repeat （NBS-LRR） genes; however, the long-term evolutionary history of these resistance genes has not been fully understood, This study...Plant genomes harbor dozens to hundreds of nucleotide-binding site-leucine-rich repeat （NBS-LRR） genes; however, the long-term evolutionary history of these resistance genes has not been fully understood, This study focuses on five Brassicaceae genomes and the Carica papaya genome to explore changes in NBS-LRR genes that have taken place in this Rosid II lineage during the past 72 million years. Various numbers of NBS-LRR genes were identified from Arabidopsis lyrata （198）, A. thaliana （165）, Brassica rapa （204）, Capsella rubella （127）, Thellungiella salsuginea （88）, and C. papaya （51）. In each genome, the identified NBS-LRR genes were found to be unevenly distributed among chromosomes and most of them were clustered together. Phylogenetic analysis revealed that, before and after Brassicaceae speciation events, both toll/interleukin-1 receptor-NBS-LRR （TNL） genes and non-toll/interleukin-1 receptor-NBS-LRR （nTNL） genes exhibited a pattern of first expansion and then contraction, suggesting that both subclasses of NBS-LRR genes were responding to pathogen pressures synchronically. Further, by examining the gain/loss of TNL and nTNL genes at different evolutionary nodes, this study revealed that both events often occurred more drastically in TNL genes. Finally, the phylogeny of nTNL genes suggested that this NBS-LRR subclass is composed of two separate ancient gene types： RPW8-NBS-LRR and Coiled-coiI-N BS-LRR.展开更多
Based on the idea of adjoint method and the dynamic evolution method,a new optimum aerodynamic design technique is presented in this paper.It can be applied to the optimum problems with a large number of design variab...Based on the idea of adjoint method and the dynamic evolution method,a new optimum aerodynamic design technique is presented in this paper.It can be applied to the optimum problems with a large number of design variables and is time saving.The key of the new method lies in that the optimization process is regarded as an unsteady evolution,i.e.,the optimization is executed,simultaneously with solving the unsteady flow governing equations and adjoint equations.Numerical examples for both the inverse problem and drag minimization using Euler equations have been presented,and the results show that the method presented in this paper is more efficient than the optimum methods based on the steady flow solution and the steady solution of adjoint equations.展开更多
Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,includ...Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,including a H_(2)O_(2)molecule dissociated on the metal single site to form the(metal_(1)-N_(x))=O active site,and followed by the dissociation of another H_(2)O_(2)on the other side of metal atom to form O=(metal_(1)-N_(x))=O intermediate center,which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol.In this manuscript,we report a Cu SAC with nitrogen and oxygen dual-coordination(Cu1-N3O1 moiety)that doesn’t need the first H_(2)O_(2)activation process,as verified by both experimental and density function theory(DFT)calculations results.Compared with the counterpart nitrogen-coordinated Cu SAC(denoted as Cu1/NC),Cu SAC with nitrogen and oxygen dual-coordination(denoted as Cu1/NOC)exhibits 2.5 times higher turnover frequency(TOF)and 1.6 times higher utilization efficiency of H_(2)O_(2).Particularly,the coordination number(CN)of Cu atom in Cu1/NOC maintains four even after H_(2)O_(2)treatment and reaction.Combining DFT calculations,the dynamic evolution of single atomic Cu with nitrogen and oxygen dualcoordination in hydroxylation of benzene is proposed.These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.展开更多
In order to quantitatively describe the geoelectric precursor anomaly in the short-impending process of earthquakes, a new geoelectric precursor index — (monthly) relative change rate of ground resistivity, R ρ...In order to quantitatively describe the geoelectric precursor anomaly in the short-impending process of earthquakes, a new geoelectric precursor index — (monthly) relative change rate of ground resistivity, R ρ (t) , is designed. Using this index and choosing the internationally accepted ground resistivity data before the Tangshan M =7.8 earthquake of July 28, 1976, the features of dynamic evolution pattern of R ρ(t) are studied. The results show that: ① about 10～9 months before earthquake, the ground resistivity in a certain range around the epicentral region begins to display the anomaly of accelerating descent, and the rate of descent is higher in the epicentral region than in surrounding areas; ② with the shortening of countdown before earthquake, the R ρ(t) value in epicentral region increases gradually (ground resistivity value decreases at an increasing rate); ③ the R ρ(t) value has the epicentral area as a center and its contour lines propagate towards surrounding areas with the shortening of countdown before earthquake; ④after the R ρ(t) value in epicentral region has descended at increasing rate to reach an extremity [ R ρ(t) = (7.0], it turns to descend at decreasing rate (2～3 months) and earthquake occurs when it accelerates again. Meanwhile, earthquake occurs when the contour lines of R ρ(t) stop propagating towards surrounding areas and turn to shrink back (2～3 months later). Its physical process can be explained by the″ swollen hypothesis″ of Prof. Fu and the theory of ″Slip-weakening and rockmass instability″ of Mei, Niu, et al ..展开更多
We propose an evolution model of cooperative agent and noncooperative agent aggregates to investigate the dynamic evolution behaviors of the system and the effects of the competing microscopic reactions on the dynamic...We propose an evolution model of cooperative agent and noncooperative agent aggregates to investigate the dynamic evolution behaviors of the system and the effects of the competing microscopic reactions on the dynamic evolution. In this model, each cooperative agent and noncooperative agent are endowed with integer values of cooperative spirits and nonco- operative spirits, respectively. The cooperative spirits of a cooperative agent aggregate and the noncooperative spirits of a noncooperative agent aggregate change via four competing microscopic reaction schemes： the win-win reaction between two cooperative agents, the lose-lose reaction between two noncooperative agents, the win-lose reaction between a coop- erative agent and a noncooperative agent （equivalent to the migration of spirits from cooperative agents to noncooperative agents）, and the cooperative agent catalyzed decline of noncooperative spirits. Based on the generalized Smoluchowski＇s rate equation approach, we investigate the dynamic evolution behaviors such as the total cooperative spirits of all coop- erative agents and the total noncooperative spirits of all noncooperative agents. The effects of the three main groups of competition on the dynamic evolution are revealed. These include： （i） the competition between the lose-lose reaction and the win-lose reaction, which gives rise to respectively the decrease and increase in the noncooperative agent spirits; （ii） the competition between the win-win reaction and the win-lose reaction, which gives rise to respectively the increase and decrease in the cooperative agent spirits; （iii） the competition between the win-lose reaction and the catalyzed-decline reaction, which gives rise to respectively the increase and decrease in the noncooperative agent spirits.展开更多
We have set up a new reduced model Hamiltonian for the polariton system, in which the nonlinear interaction contains the rotating term k l （ a ＋ b ＋ ab＋） and the attractive two-mode squeezed coupling - k2 （ a ...We have set up a new reduced model Hamiltonian for the polariton system, in which the nonlinear interaction contains the rotating term k l （ a ＋ b ＋ ab＋） and the attractive two-mode squeezed coupling - k2 （ a ＋ b＋ ＋ ab ） . The dynamical evolution of this system has been solved and the nonclassical features relevant to the second-order and high-order squeezing have been obtained in an analytical form. For the first time, in contrast to the existing result, we have confirmed for the phonon field that the attractive two-mode squeezed interaction will not only result in the second-order and high-order squeezing in X-component with the time evolution, but also in time average. Furthermore, the phenomena of collapse and revival of inversion will occur as well in the time evolution of the average number of photon and phonon, as also in the second-order and high-order squeezing of photon field, particularly, in the high-order squeezing of phonon field.展开更多
Electrochemical trepanning(ECTr)is an effective electrochemical machining(ECM)technique that can be used to manufacture the integral components of aero-engine compressors.This study focused on the dynamic evolution of...Electrochemical trepanning(ECTr)is an effective electrochemical machining(ECM)technique that can be used to manufacture the integral components of aero-engine compressors.This study focused on the dynamic evolution of ECTr for production of inner blisks(bladed disks)with a special chamfer structure at blade tip.Due to the existence of chamfer,the ECTr process of inner blades is in a non-equilibrium state during the early stages,and the physical field changes in the machining gap are complex,making it difficult to predict the forming process.In this paper,a dynamic evolution model(DEM)of inner blade ECTr with a special chamfer at blade tip structure is proposed,and an ECTr multi-physical fields simulation study was carried out.The evolution of the chamfer at blade tip was analyzed and data related to chamfer were predicted based on the dependence of anode boundary properties with machining time and feed rate.In addition,the dis-tributions of current density,electrolyte flow rate,bubble volume fraction,temperature rise,and electrolyte conductivity in the machining area at different times were obtained by combining them with the multi-physical fields simulation results.Subsequently,a series of ECTr experiments were conducted,in which,as the feed rate increased,the surface quality and machining accuracy of the inner blades were improved.Compared with the simulation results,the error in machining accu-racy of the chamfer profile is controlled within±2%,and the machining accuracy of the blade full profile was controlled within±0.2 mm,indicating that the model proposed in this study was effec-tive in predicting the evolution of inner blades ECTr with chamfer structures at blade tip.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2022CDJQY-012)the Innovation Group Science Foundation of the Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyj-cxttX0003).
文摘Coralline soils,specialized materials found extensively in the South China Sea,are playing an increasingly vital role in engineering projects.However,like most terrigenous soils,fine-grained coral soil is prone to shrinkage and cracking,which can significantly affect its engineering properties and ultimately jeopardize engineering safety.This paper presents a desiccation cracking test of fine-grained coral soil,with a particular focus on the thickness effect.The study involved measuring the water content and recording the evolution of desiccation cracking.Advanced image processing technology is employed to analyze the variations in crack parameters,clod parameters,fractal dimensions,frequency distributions,and desiccation cracking propagation velocities of fine-grained coral soil.Furthermore,the dynamic evolution of desiccation cracking under the influence of layer thickness is analyzed.A comprehensive crack evolution model is proposed,encompassing both top-down and bottom-up crack propagation,as well as internal tensile cracking.This work introduces novel metrics for the propagation velocity of the total crack area,the characteristic propagation velocities of desiccation cracks,and the acceleration of crack propagation.Through data fitting,theoretical formulas for soil water evaporation,propagation velocities of desiccation cracks,and crack propagation acceleration are derived,laying a foundation for future soil cracking theories.
基金supported by the Major Scientific and Technological Projects of CNPC under grant ZD2019-183-006the National Science and Technology Major Project of China(2016ZX05014002-006)the National Natural Science Foundation of China(42072234)。
文摘This study aims to elucidate the dynamic evolution mechanism of the fracturing fracture system during the exploration and development of complex oil and gas reservoirs.By integrating methods of rock mechanical testing,logging calculation,and seismic inversion technology,we obtained the current insitu stress characteristics of a single well and rock mechanical parameters.Simultaneously,significant controlling factors of rock mechanical properties were analyzed.Subsequently,by coupling hydraulic fracturing physical experiments with finite element numerical simulation,three different fracturing models were configured:single-cluster,double-cluster,and triple-cluster perforations.Combined with acoustic emission technology,the fracture initiation mode and evolution characteristics during the loading process were determined.The results indicate the following findings:(1)The extension direction and length of the fracture are significantly controlled by the direction of the maximum horizontal principal stress.(2)Areas with poor cementation and compactness exhibit complex fracture morphology,prone to generating network fractures.(3)The interlayer development of fracturing fractures is controlled by the strata occurrence.(4)Increasing the displacement of fracturing fluid enlarges the fracturing fracture length and height.This research provides theoretical support and effective guidance for hydraulic fracturing design in tight oil and gas reservoirs.
基金Projects(42002266,51908288)supported by the National Natural Science Foundation of ChinaProject(2020M673654)supported by the Chinese Postdoctoral Science FoundationProject(2019K284)supported by Jiangsu Post-doctoral Research Funding Program,China。
文摘Rock blocks sliding along discontinuities can cause serious disasters,such as landslides,earthquakes,or rock bursts.The shear rate-dependent behavior is a typical time-dependent behavior of a rock discontinuity,and it is closely related to the stability of a rock block.To further study the shear rate-dependent behavior of rock discontinuities,shear tests with alternating shear rates(SASRs)were conducted on rock discontinuities with various surface morphologies.The dynamic evolution of the shear rate dependency was studied in detail based on the shear test results,and three stages were identified with respect to the shear stress and shear deformation states.The test results revealed that dynamic changes in shear stiffness and the energy storage abilities of the rock discontinuities occurred in relation to the shear rate-dependent behavior of crack growth,which increased with an increase in normal stress and/or the joint roughness coefficient.The stage of decreasing shear stiffness corresponded to a stage of noticeable shear rate-dependency,and the shear rate was found to have no influence on the initial crack stress.
基金National Key Research and Development Program of China(2019YFB1600400)National Natural Science Foundation of China(72174035)+2 种基金National Natural Science Foundation of China(71774018)Liaoning Revitalization Talents Program(XLYC2008030)Liaoning Provincial Natural Science Foundation Shipping Joint Foundation Program(2020-HYLH-20)。
文摘It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.
基金supported by National Natural Science Foundation of China[Grant number.71673034]Postdoctoral Research Founda‐tion of China[Grant number.2021M692654]+1 种基金Natural Science Basic Research Program of Shaanxi Province[Grant number.2020JQ282]Social Science Foundation of Shaanxi Province[Grant number.2020R042].
文摘To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the regional differences and evolutionary trends in the development quality of China’power sector has a high value to inspire the next improvement direction toward how to integrate regional power recourses to an overall optimization level.Motived by this purpose,this paper uses the entropy method to evaluate the com‐prehensive and subsystem indices of the development quality of the power industry,and reveals their re‐gional differences and evolutionary trends with the help of the Dagum Gini coefficient and Kernel density es‐timation methods.The findings show that:There are obvious regional differences in the development quality of China’s power industry,and the differences are steadily declining in all regions except the West.Regional differences are mainly derived from inter-regional differences,with the largest inter-regional differences in the East-Northeast region.Intra-regional differences show a distribution pattern of East>West>North‐east>Center.
文摘Following a new train of thinking, this paper has explored first the potential information in the ground resistivitydata observed by the existing geoelectric observation system, investigated and proposed a new dimensionlessgeoelectric precursor factor, the degree of ground resistivity anisotropy, S, and studied the characteristics of dynamic evolution pattern of S during the seismogenic process. The results show that, during the seismogenic process, the degree of ground resistivity anisotropy (S) displays h process of 'normal' → 'abnormal strengthening(amplitude, range)' → 'abnormal weakening'→ 'earthquake occurrence'→ 'normal'. The earthquake wouldoccur at the time when the S value has entered the late stage of strengthening and turns to weaken and in the gradient belt on the margin ofS anomaly region. The dynamic evolution pattern ofS reflects the changes of the tectonicstress field during the seismogenic process. Therefore, it would be possible to trace the process of earthquake generation and occurrence from the dynamic evolution pattern ofS so as to service eaJ'thquake prediction.
基金Supported by the National Natural Science Foundation of China under Grant No 10975057the Programme of Introducing Talents of Discipline to Universities under Grant No B08033
文摘Empirical data show that most of the degree distribution of airline networks assume a double power law. In this work, firstly, we assume cities as sites, flight between two cities as an edge between two sites, and build a dynamic evolution model for airline networks by improving the BA model, in which the conception of attractiveness plays a decisive role in the course of evolution of the networks. To this end, we discuss whether the attractiveness depends on the site label s or not separately, finally we obtain analytic degree distribution. As a result, if the attractiveness of a site is independent of the degree distribution of sites, which will follow the double power law, otherwise, it will be scale-free. Moreover, degree distribution depends on the parameters of the models, and some parameters aye more sensitive than others.
基金Projects(61173026,61373045,61202039)supported by the National Natural Science Foundation of ChinaProjects(K5051223008,BDY221411)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2012AA02A603)supported by the High-Tech Research and Development Program of China
文摘As the ability of a single agent is limited while information and resources in multi-agent systems are distributed, cooperation is necessary for agents to accomplish a complex task. In the open and changeable environment on the Internet, it is of great significance to research a system flexible and capable in dynamic evolution that can find a collaboration method for agents which can be used in dynamic evolution process. With such a method, agents accomplish tasks for an overall target and at the same time, the collaborative relationship of agents can be adjusted with the change of environment. A method of task decomposition and collaboration of agents by improved contract net protocol is introduced. Finally, analysis on the result of the experiments is performed to verify the improved contract net protocol can greatly increase the efficiency of communication and collaboration in multi-agent system.
基金supported by the National Natural Science Foundation of China(No.22175030)the Open Project of State Key Laboratory of Supramolecular Structure and Materials(No.sklssm 202406).
文摘The electrochemical nitrate reduction reaction(eNO_(3)^(-)RR)is considered an effective approach for converting nitrate-containing wastewater to ammonia.The adsorption and activation of NO_(3)^(-)is the critical step for many materials and the high energy barrier inhibits the continuation of the reduction reaction.The Co nanoparticles encapsulated in the carbon layer we prepared spontaneously react with NO_(3)^(-)and the resulting Co^(2+)is then reduced by electroreduction to Co^(0),which circulates continuously.This resulted in overcoming the energy input required for NO_(3)^(-)adsorption and conversion,thereby increasing the catalytic activity.At the same time,the morphology of the catalyst reconstructed from a dodecahedron to an interwoven nanosheet structure and the increased surface area also gives it better properties.The obtained Co(OH)_(2)@Co-N-C has an excellent eNO_(3)^(-)RR of 2774.7μg·h^(-1)·cm^(-2)with a Faraday efficiency of 81.4%in neutral solution.At the same time,the material-modified electrode can run stably for more than 100 h.Our work provides a new idea for the design of Co-based catalysts for eNO_(3)^(-)RR.
基金The Major Program of National Social Science Foundation of China(23&ZD108)The General Program of National Social Science Foundation of China(23BJY171)+1 种基金The China Postdoctoral Special Funding Project(2024T170590)The Liaoning Province“Xingliao Talent Program”Project(XLYC2410051)。
文摘Agricultural new quality productive forces are the key foundation for realizing high-quality agricultural development.This study constructs the evaluation indicator system of agricultural new quality productive forces(ANQPFs)from three dimensions:agricultural laborers,agricultural labor objects,and agricultural labor resources.The equal weight method,entropy method,and CRITIC method are comprehensively applied to measure ANQPFs in China from 2011 to 2021.The Dagum's Gini coefficient,variance decomposition,kernel density estimation,Markov chain,and obstacle degree model are used to analyze regional differences,structural differences,dynamic evolution,and obstacle factors of ANQPFs.The findings show that:(1)There is an upward trend in ANQPFs in the national and the three major regions during the study period,while there are significant differences in ANQPFs by regions,which are characterized by a decreasing distribution from the east to the central,and then to the west.(2)The overall differences in ANQPFs have tended to widen,with inter-regional differences being the main source.(3)Agricultural labor object differences and agricultural labor resource differences are the main structural sources of ANQPFs development differences in China,with agricultural labor resource differences replacing agricultural labor object differences as the top source of ANQPFs differences after 2016.(4)The ANQPFs of the national and three regions show the distribution dynamics of"overall increase,absolute differences widen",and there is the phenomenon of"club convergence"in ANQPFs.(5)The number of Taobao villages,rural entrepreneurial activities,the number of agricultural science and technology patents per capita,and expenditure on agricultural science and technology activities are the main factors obstructing the development of ANQPFs.
基金The National Natural Science Foundation of China(32161143025,32160279,31960249)The Science and Technology Major Project of Inner Mongolia(2022YFHH0017,2021ZD0011)+1 种基金The Ordos Science and Technology Plan(2022EEDSKJZDZX010,2022EEDSKJXM005)The Mongolian Foundation for Science and Technology(NSFC_2022/01,CHN2022/276)。
文摘Rapid climate change and human disturbance have caused serious damage and shrinkage of the wetlands in the Mongolian Plateau,posing severe challenges to environmental development.Based on remote sensing images and DEM data,this study established a series of datasets for lakeside wetlands in the Mongolian Plateau in 2000,2010 and 2020,and investigated the dynamic evolution of lakeside wetlands in the Mongolian Plateau through spatial and temporal analyses.The results showed that in 2000,there were 564 lakes(>1 km^(2))in the Mongolian Plateau,with a total area of about 55216.47 km^(2).Compared with 2000,the area of lakes in 2010 was significantly reduced,and there was a significant increase in the number of woody marshes and a reduction in the number of herbaceous marshes.In 2020,the lakes in the central part of the Mongolian Plateau were smaller than in 2010.The areas of lakes in the western,southern and eastern regions were increasing,and the areas of herbaceous swamps,woody marshes and meadows were increasing overall.Lakes,bare land and saline-alkali land decreased overall.The degree of salinization was reduced over the study period.There was a significant correlation between the Adaptive Palmer Drought Index(scPDSI)and lake area.In the past two decades,the climatic factors and human activities of the Mongolian Plateau have profoundly affected the evolution of the lakeside wetlands.We should prioritize the protection of lakes and wetland resources in order to achieve the dynamic balance of wetland ecology.
基金supported by National Natural Science Foundation of China(No.42272291,No.42077176)the Strategic Research Program of the National Natural Science Foundation of China(No.42242202).
文摘Lake wetlands play a crucial role as global carbon sinks,significantly contributing to carbon storage and ecological balance.This study estimates the quarterly carbon storage in the Dongting Lake wetland for the years 2010,2015,and 2020,using MODIS remote sensing imagery and the InVEST model.A Structural Equation Model(SEM)was then employed to analyze the driving factors behind changes in carbon storage.Results show that intra-annual carbon storage increases and then decreases,with maximum level in the third quarter(average of 34.242 Tg)and a minimum one in the first quarter(average of 21.435 Tg).From 2010 to 2020,inter-annual carbon storage variations initially exhibited an increasing trend before decreasing,with the peak annual average carbon storage reaching 32.230 Tg in 2015.Notably,the coefficient of variation for intra-annual carbon storage increased from 8.5%in 2010 to 25.8%in 2020.Key driving factors that influence carbon storage changes include surface solar radiation,temperature,and water level,with carbon storage positively correlated with surface solar radiation and temperature,and negatively correlated with water level.These findings reveal the spatiotemporal evolution characteristics of carbon storage in the Dongting Lake wetland,offering scientific guidance for wetland conservation and regional climate adaptation policies.
基金supported by National Key Research and Development Program"Advanced Structures and Composite Materials"Special Project[Grant No.2024YFB3712800]the Fundamental Research Funds for the Central Universities[Grant No.DUT22-LAB605]Liaoning Province's"Unveiling the List and Leading the Way"Science and Technology Research and Development Special Project[Grant No.2022JH1/10400043]。
文摘Poly(phthalazinone ether sulfone ketone)(PPESK)is a new-generation high-performance thermoplastic resin that exhibits excellent thermal stability and mechanical properties.However,its damage and failure mechanisms under high-temperature and high-strain-rate coupling conditions remain unclear,significantly limiting the engineering applications of PPESK-based composites in extreme environments such as aerospace.To address this issue,in this study,a temperature-controlled split Hopkinson pressure bar experimental platform was developed for dynamic tensile/compressive loading scenarios.Combined with scanning electron microscopy and molecular dynamics simulations,the thermomechanical behavior and failure mechanisms of PPESK were systematically investigated over the temperature range of 293-473 K.The study revealed a novel"dynamic hysteresis brittle behavior"and its underlying"segmental activation±response lag antagonistic mechanism".The results showed that the strain-rate-induced response lag of polymer chain segments significantly weakened the viscous dissipation capacity activated by thermal energy at elevated temperatures.Although high-strain-rate conditions led to notable enhancement in the dynamic strength of the material(with an increase of 8%-233%,reaching 130%-330%at elevated temperatures),the fracture surface morphology tended to become smoother,and brittle fracture characteristics became more pronounced.Based on these findings,a temperature±strain rate hysteresis antagonistic function was constructed,which effectively captured the competitive relationship between temperature-driven relaxation behavior and strain-rateinduced hysteresis in thermoplastic resins.A multiscale damage evolution constitutive model with temperature±rate coupling was subsequently established and numerically implemented via the VUMAT user subroutine.This study not only unveils the nonlinear damage mechanisms of PPESK under combined service temperatures and dynamic/static loading conditions,but also provides a strong theoretical foundation and engineering guidance for the constitutive modeling and parametric design of thermoplastic resin-based materials.
基金supported by the National Natural Science Foundation of China(30930008,31170210,31200177,91231102,31300190,31400201 and 31470327)China Postdoctoral Science Foundation(2013M540435 and 2014T70503)+3 种基金Postdoctoral Science Foundation of Jiangsu Province(1302131C)Fundamental Research Funds for the Central Universities(20620140546 and 20620140558)Natural Science Founding of Jiangsu Province(BK20130565)Qing Lan Project of Jiangsu Province
文摘Plant genomes harbor dozens to hundreds of nucleotide-binding site-leucine-rich repeat （NBS-LRR） genes; however, the long-term evolutionary history of these resistance genes has not been fully understood, This study focuses on five Brassicaceae genomes and the Carica papaya genome to explore changes in NBS-LRR genes that have taken place in this Rosid II lineage during the past 72 million years. Various numbers of NBS-LRR genes were identified from Arabidopsis lyrata （198）, A. thaliana （165）, Brassica rapa （204）, Capsella rubella （127）, Thellungiella salsuginea （88）, and C. papaya （51）. In each genome, the identified NBS-LRR genes were found to be unevenly distributed among chromosomes and most of them were clustered together. Phylogenetic analysis revealed that, before and after Brassicaceae speciation events, both toll/interleukin-1 receptor-NBS-LRR （TNL） genes and non-toll/interleukin-1 receptor-NBS-LRR （nTNL） genes exhibited a pattern of first expansion and then contraction, suggesting that both subclasses of NBS-LRR genes were responding to pathogen pressures synchronically. Further, by examining the gain/loss of TNL and nTNL genes at different evolutionary nodes, this study revealed that both events often occurred more drastically in TNL genes. Finally, the phylogeny of nTNL genes suggested that this NBS-LRR subclass is composed of two separate ancient gene types： RPW8-NBS-LRR and Coiled-coiI-N BS-LRR.
文摘Based on the idea of adjoint method and the dynamic evolution method,a new optimum aerodynamic design technique is presented in this paper.It can be applied to the optimum problems with a large number of design variables and is time saving.The key of the new method lies in that the optimization process is regarded as an unsteady evolution,i.e.,the optimization is executed,simultaneously with solving the unsteady flow governing equations and adjoint equations.Numerical examples for both the inverse problem and drag minimization using Euler equations have been presented,and the results show that the method presented in this paper is more efficient than the optimum methods based on the steady flow solution and the steady solution of adjoint equations.
基金We thank the National Key R&D Program of China(Nos.2018YFA0703503 and 2018YFA0208504)the National Natural Science Foundation of China(No.21932006)the Youth Innovation Promotion Association of CAS(No.2017049)for financial support.
文摘Single atom catalysts(SACs)with metal_(1)-N_(x)sites have shown promising activity and selectivity in direct catalytic oxidation of benzene to phenol.The reaction pathway is considered to be involving two steps,including a H_(2)O_(2)molecule dissociated on the metal single site to form the(metal_(1)-N_(x))=O active site,and followed by the dissociation of another H_(2)O_(2)on the other side of metal atom to form O=(metal_(1)-N_(x))=O intermediate center,which is active for the adsorption of benzene molecule via the formation of a C-O bond to form phenol.In this manuscript,we report a Cu SAC with nitrogen and oxygen dual-coordination(Cu1-N3O1 moiety)that doesn’t need the first H_(2)O_(2)activation process,as verified by both experimental and density function theory(DFT)calculations results.Compared with the counterpart nitrogen-coordinated Cu SAC(denoted as Cu1/NC),Cu SAC with nitrogen and oxygen dual-coordination(denoted as Cu1/NOC)exhibits 2.5 times higher turnover frequency(TOF)and 1.6 times higher utilization efficiency of H_(2)O_(2).Particularly,the coordination number(CN)of Cu atom in Cu1/NOC maintains four even after H_(2)O_(2)treatment and reaction.Combining DFT calculations,the dynamic evolution of single atomic Cu with nitrogen and oxygen dualcoordination in hydroxylation of benzene is proposed.These findings provide an efficient route to improve the catalytic performance through regulating the coordination environments of SACs and demonstrate a new reaction mechanism in hydroxylation of benzene to phenol reaction.
文摘In order to quantitatively describe the geoelectric precursor anomaly in the short-impending process of earthquakes, a new geoelectric precursor index — (monthly) relative change rate of ground resistivity, R ρ (t) , is designed. Using this index and choosing the internationally accepted ground resistivity data before the Tangshan M =7.8 earthquake of July 28, 1976, the features of dynamic evolution pattern of R ρ(t) are studied. The results show that: ① about 10～9 months before earthquake, the ground resistivity in a certain range around the epicentral region begins to display the anomaly of accelerating descent, and the rate of descent is higher in the epicentral region than in surrounding areas; ② with the shortening of countdown before earthquake, the R ρ(t) value in epicentral region increases gradually (ground resistivity value decreases at an increasing rate); ③ the R ρ(t) value has the epicentral area as a center and its contour lines propagate towards surrounding areas with the shortening of countdown before earthquake; ④after the R ρ(t) value in epicentral region has descended at increasing rate to reach an extremity [ R ρ(t) = (7.0], it turns to descend at decreasing rate (2～3 months) and earthquake occurs when it accelerates again. Meanwhile, earthquake occurs when the contour lines of R ρ(t) stop propagating towards surrounding areas and turn to shrink back (2～3 months later). Its physical process can be explained by the″ swollen hypothesis″ of Prof. Fu and the theory of ″Slip-weakening and rockmass instability″ of Mei, Niu, et al ..
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10875086 and 11175131)
文摘We propose an evolution model of cooperative agent and noncooperative agent aggregates to investigate the dynamic evolution behaviors of the system and the effects of the competing microscopic reactions on the dynamic evolution. In this model, each cooperative agent and noncooperative agent are endowed with integer values of cooperative spirits and nonco- operative spirits, respectively. The cooperative spirits of a cooperative agent aggregate and the noncooperative spirits of a noncooperative agent aggregate change via four competing microscopic reaction schemes： the win-win reaction between two cooperative agents, the lose-lose reaction between two noncooperative agents, the win-lose reaction between a coop- erative agent and a noncooperative agent （equivalent to the migration of spirits from cooperative agents to noncooperative agents）, and the cooperative agent catalyzed decline of noncooperative spirits. Based on the generalized Smoluchowski＇s rate equation approach, we investigate the dynamic evolution behaviors such as the total cooperative spirits of all coop- erative agents and the total noncooperative spirits of all noncooperative agents. The effects of the three main groups of competition on the dynamic evolution are revealed. These include： （i） the competition between the lose-lose reaction and the win-lose reaction, which gives rise to respectively the decrease and increase in the noncooperative agent spirits; （ii） the competition between the win-win reaction and the win-lose reaction, which gives rise to respectively the increase and decrease in the cooperative agent spirits; （iii） the competition between the win-lose reaction and the catalyzed-decline reaction, which gives rise to respectively the increase and decrease in the noncooperative agent spirits.
基金Supported by the Foundation of Scientific Research Education and Innovations under Grant No.11609506,Jinan University
文摘We have set up a new reduced model Hamiltonian for the polariton system, in which the nonlinear interaction contains the rotating term k l （ a ＋ b ＋ ab＋） and the attractive two-mode squeezed coupling - k2 （ a ＋ b＋ ＋ ab ） . The dynamical evolution of this system has been solved and the nonclassical features relevant to the second-order and high-order squeezing have been obtained in an analytical form. For the first time, in contrast to the existing result, we have confirmed for the phonon field that the attractive two-mode squeezed interaction will not only result in the second-order and high-order squeezing in X-component with the time evolution, but also in time average. Furthermore, the phenomena of collapse and revival of inversion will occur as well in the time evolution of the average number of photon and phonon, as also in the second-order and high-order squeezing of photon field, particularly, in the high-order squeezing of phonon field.
基金the National Nature Science Foundation of China (52275435)the National Natural Science Foundation of China for Creative Research Groups (51921003)the National Science and Technology Major Project (2017-VII-0004-0097).
文摘Electrochemical trepanning(ECTr)is an effective electrochemical machining(ECM)technique that can be used to manufacture the integral components of aero-engine compressors.This study focused on the dynamic evolution of ECTr for production of inner blisks(bladed disks)with a special chamfer structure at blade tip.Due to the existence of chamfer,the ECTr process of inner blades is in a non-equilibrium state during the early stages,and the physical field changes in the machining gap are complex,making it difficult to predict the forming process.In this paper,a dynamic evolution model(DEM)of inner blade ECTr with a special chamfer at blade tip structure is proposed,and an ECTr multi-physical fields simulation study was carried out.The evolution of the chamfer at blade tip was analyzed and data related to chamfer were predicted based on the dependence of anode boundary properties with machining time and feed rate.In addition,the dis-tributions of current density,electrolyte flow rate,bubble volume fraction,temperature rise,and electrolyte conductivity in the machining area at different times were obtained by combining them with the multi-physical fields simulation results.Subsequently,a series of ECTr experiments were conducted,in which,as the feed rate increased,the surface quality and machining accuracy of the inner blades were improved.Compared with the simulation results,the error in machining accu-racy of the chamfer profile is controlled within±2%,and the machining accuracy of the blade full profile was controlled within±0.2 mm,indicating that the model proposed in this study was effec-tive in predicting the evolution of inner blades ECTr with chamfer structures at blade tip.
