Among the geo-hazards caused by the great Wenchuan Earthquake, the rapid and long runout rockslide-debris flow is of primary concern due to the large volume of displaced material and the resultant catastrophic impacts...Among the geo-hazards caused by the great Wenchuan Earthquake, the rapid and long runout rockslide-debris flow is of primary concern due to the large volume of displaced material and the resultant catastrophic impacts to the landscape and socioeconomic structure. In order to analyze the dynamical process of this kind of geo-hazard, the Donghekou rockslide-debris flow is given as an example in this paper. This event, which killed 780 people, initiated at an elevation of 1300 m with a total long run-out distance of more than 2400 m. The slide mass is mainly composed of dolomite limestone and siliceous limestone of Sinian system, together with carbon slate and phyllite of Cambrian. During the processes from slide initiation to the final cessation of slide movement, five dynamic stages took place, here identified as the initiation stage, the acceleration of movement stage, the air-blast effect stage, the impact and redirection stage and the long runout slidematerial accumulation stage. Field investigations indicate that due to the effects of the earthquake, the dynamics of the Donghekou rockslide-debris flow are apparently controlled by geologic and tectonic conditions, the local geomorphological aspects of the terrain, and the microstructural and macroscopic mechanical properties of rocks which compose the slide mass. These three main factors which dictate the Donghekou rockslide-debris flow dynamics are discussed in detail in this paper, and significant results of field investigations and tests of materials are presented. The above dynamical processes are analyzed in this paper, and some useful conclusions have been gained.展开更多
The cold tongue mode(CTM),which represents the out-of-phase relationship in sea surface temperature anomaly(SSTA)variability between the Pacific cold tongue region and elsewhere in the tropical Pacific,shows a long-te...The cold tongue mode(CTM),which represents the out-of-phase relationship in sea surface temperature anomaly(SSTA)variability between the Pacific cold tongue region and elsewhere in the tropical Pacific,shows a long-term cooling trend in the eastern equatorial Pacific.In this study,we investigate how well the CTM is reproduced in historical simulations generated by the 20 models considered in Phase 5 of the Coupled Model Intercomparison Project(CMIP5).Qualitatively,all 20 models roughly capture the cooling SSTA associated with the CTM.However,a quantitative assessment(i.e.,Taylor diagrams and the ratio of the trend between the simulations and observations)shows that only five of these 20 models(i.e.,CESM1-CAM5,CMCC-CM,FGOALS-g2,IPSL-CM5B-LR,and NorESM1-M)can reproduce with useful accuracy the spatial pattern and long-term trend of the CTM.We find that these five models generally simulate the main ocean dynamical process associated with the CTM.That is,these models adequately capture the long-term cooling trend in the vertical advection of the anomalous temperature by the mean upwelling.We conclude that the performance of these CMIP5 models,with respect to simulations of the long-term cooling trend associated with the vertical advection,and the related long-term decreasing trend of the vertical gradient of the oceanic temperature anomaly,can play an important role in successful reproduction of the CTM.展开更多
Data-driven process monitoring is an effective approach to assure safe operation of modern manufacturing and energy systems,such as thermal power plants being studied in this work.Industrial processes are inherently d...Data-driven process monitoring is an effective approach to assure safe operation of modern manufacturing and energy systems,such as thermal power plants being studied in this work.Industrial processes are inherently dynamic and need to be monitored using dynamic algorithms.Mainstream dynamic algorithms rely on concatenating current measurement with past data.This work proposes a new,alternative dynamic process monitoring algorithm,using dot product feature analysis(DPFA).DPFA computes the dot product of consecutive samples,thus naturally capturing the process dynamics through temporal correlation.At the same time,DPFA's online computational complexity is lower than not just existing dynamic algorithms,but also classical static algorithms(e.g.,principal component analysis and slow feature analysis).The detectability of the new algorithm is analyzed for three types of faults typically seen in process systems:sensor bias,process fault and gain change fault.Through experiments with a numerical example and real data from a thermal power plant,the DPFA algorithm is shown to be superior to the state-of-the-art methods,in terms of better monitoring performance(fault detection rate and false alarm rate)and lower computational complexity.展开更多
The exothermic efficiency of microwave heating an electrolyte/water solution is remarkably high due to the dielectric heating by orientation polarization of water and resistance heating by the Joule process occurred s...The exothermic efficiency of microwave heating an electrolyte/water solution is remarkably high due to the dielectric heating by orientation polarization of water and resistance heating by the Joule process occurred simultaneously compared with pure water.A three-dimensional finite element numerical model of multi-feed microwave heating industrial liquids continuously flowing in a meter-scale circular tube is presented.The temperature field inside the applicator tube in the cavity is solved by COMSOL Multiphysics and professional programming to describe the momentum,energy and Maxwell's equations.The evaluations of the electromagnetic field,the temperature distribution and the velocity field are simulated for the fluids dynamically heated by singleand multi-feed microwave system,respectively.Both the pilot experimental investigations and numerical results of microwave with single-feed heating for fluids with different effective permittivity and flow rates show that the presented numerical modeling makes it possible to analyze dynamic process of multi-feed microwave heating the industrial liquid.The study aids in enhancing the understanding and optimizing of dynamic process in the use of multi-feed microwave heating industrial continuous flow for a variety of material properties and technical parameters.展开更多
The western coast of Hainan Island exhibits a savanna landscape. Many types of sand dunes, including transverse dune ridges, longitudinal dune ridges, elliptical dunes, coppice dunes, and climbing dunes, are widely di...The western coast of Hainan Island exhibits a savanna landscape. Many types of sand dunes, including transverse dune ridges, longitudinal dune ridges, elliptical dunes, coppice dunes, and climbing dunes, are widely distributed in the coastal zone. In winter, high-frequency and high-energy NE winds （dominant winds） are prevalent, with a resultant drift direction （RDD） of S35.6°W. In spring, low-frequency and low-energy SW secondary winds prevail, with a RDD of N25.1°E. Wind tunnel simulations revealed that the airflow over the dune surface is the main factor controlling the erosion and deposition patterns of dune surfaces and the morphological development of dunes. In the region＇s bidirectional wind environment, with two seasonally distinct energy levels, the airflow over the surface of elliptical dunes, barchan dunes, and transverse dune ridges will exhibit a transverse pattern, whereas the airflow over longitudinal dunes ridges exhibits a lateral pattern and that over climbing dunes exhibits a climbing-circumfluent pattern. These patterns represent different dynamic processes. The coastal dunes on the western coast of Hainan Island are influenced by factors such as onshore winds, sand sources, coastal slopes, rivers, and forest shelter belts. The source of the sand that supplements these dunes particularly influences the development pattern： when there is more sand, the pattern shows positive equilibrium deposition between dune ridges and dunes; otherwise, it shows negative equilibrium deposition. The presence or absence of forest shelter belts also influences deposition and dune development patterns and transformation of dune forms. Coastal dunes and inland desert dunes experience similar dynamic processes, but the former have more diversified shapes and more complex formation mechanisms.展开更多
With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process...With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process plays the main part in the ozone reduction, but the chemical process partly compensates for the transport process. In the dynamic transport process of ozone, the horizontal transport process plays the main part in the ozone reduction in May, but brings about the ozone increase in June and July. The vertical advective process gradually takes the main role in the ozone reduction in June and July. The effect of convective activities rises gradually so that this effect cannot be overlooked in July, as its magnitude is comparable to that of the net changes. The effect of the gaseous chemical process brings about ozone increases which are more than the net changes sometimes, so the chemical effect is also important.展开更多
Abstract The Nansha ultra-crust layer-block is confined by ultra-crustal boundary faults of distinctive features, bordering the Kangtai-Shuangzi-Xiongnan extensional faulted zone on the north, the Baxian-Baram-Yoca-Cu...Abstract The Nansha ultra-crust layer-block is confined by ultra-crustal boundary faults of distinctive features, bordering the Kangtai-Shuangzi-Xiongnan extensional faulted zone on the north, the Baxian-Baram-Yoca-Cuyo nappe faulted zone on the south, the Wan'an-Natuna strike-slip tensional faulted zone on the west and the Mondoro-Panay strike-slip compressive faulted zone on the east. These faults take the top of the Nansha asthenosphere as their common detachmental surface. The Cenozoic dynamic process of the ultra-crust layer-block can be divided into four stages: K2-E21, during which the northern boundary faults extended, this ultra-crust layer-block was separated from the South China-Indosinian continental margin, the Palaeo-South China Sea subducted southwards and the Sibu accretion wedge was formed; E22-E31, during which the Southwest sub-sea basin extended and orogeny was active due to the collision of the Sibu accretion wedge; E32-N11, during which the central sub-sea basin extended, the Miri accretion wedge was formed and “A-type” subduction of the southern margin of the north Balawan occurred; N12-the present, during which large-scale thrusting and napping of the boundary faults in the south and mountain-building have taken place and the South China Sea stopped its extension.展开更多
Chemical process variables are always driven by random noise and disturbances. The closed-loop con-trol yields process measurements that are auto and cross correlated. The influence of auto and cross correlations on s...Chemical process variables are always driven by random noise and disturbances. The closed-loop con-trol yields process measurements that are auto and cross correlated. The influence of auto and cross correlations on statistical process control (SPC) is investigated in detail by Monte Carlo experiments. It is revealed that in the sense of average performance, the false alarms rates (FAR) of principal component analysis (PCA), dynamic PCA are not affected by the time-series structures of process variables. Nevertheless, non-independent identical distribution will cause the actual FAR to deviate from its theoretic value apparently and result in unexpected consecutive false alarms for normal operating process. Dynamic PCA and ARMA-PCA are demonstrated to be inefficient to remove the influences of auto and cross correlations. Subspace identification-based PCA (SI-PCA) is proposed to improve the monitoring of dynamic processes. Through state space modeling, SI-PCA can remove the auto and cross corre-lations efficiently and avoid consecutive false alarms. Synthetic Monte Carlo experiments and the application in Tennessee Eastman challenge process illustrate the advantages of the proposed approach.展开更多
The kinematics and dynamics of plate tectonics are frontal subjects in geosciences and the strong earthquake occurred along the plate boundary result directly from plate movement. By analyzing Ibaraki earthquake seque...The kinematics and dynamics of plate tectonics are frontal subjects in geosciences and the strong earthquake occurred along the plate boundary result directly from plate movement. By analyzing Ibaraki earthquake sequence, it has been found that the focal fault plane shows a special image of grading expansion along the direction of strike and adjustment along the dip direction respectively. With the consideration of strike, dip and slip directions of focal mechanism, we have confirmed that Ibaraki earthquake belongs to a thrust fault earthquake occurred under the Japan Trench. The cause of the earthquake sequence is discussed in the paper. The study on the temporal-spatial distribution of the earthquake sequence with a time-scale between the year-scale spatial geodetic data and the second-scale moment tensor of the strong earthquake has indicated the dynamic process of Pacific Plate subduction under the Eurasia Plate. According to the average slip distance of earthquake and the velocity of plate movement, it is predicted that a strong earthquake might occur in recent years.展开更多
The dynamic soft sensor based on a single Gaussian process regression(GPR) model has been developed in fermentation processes.However,limitations of single regression models,for multiphase/multimode fermentation proce...The dynamic soft sensor based on a single Gaussian process regression(GPR) model has been developed in fermentation processes.However,limitations of single regression models,for multiphase/multimode fermentation processes,may result in large prediction errors and complexity of the soft sensor.Therefore,a dynamic soft sensor based on Gaussian mixture regression(GMR) was proposed to overcome the problems.Two structure parameters,the number of Gaussian components and the order of the model,are crucial to the soft sensor model.To achieve a simple and effective soft sensor,an iterative strategy was proposed to optimize the two structure parameters synchronously.For the aim of comparisons,the proposed dynamic GMR soft sensor and the existing dynamic GPR soft sensor were both investigated to estimate biomass concentration in a Penicillin simulation process and an industrial Erythromycin fermentation process.Results show that the proposed dynamic GMR soft sensor has higher prediction accuracy and is more suitable for dynamic multiphase/multimode fermentation processes.展开更多
Dynamic processes of electron transfer by optical doping in monolayer MoSe2 at 6 K are investigated via measuring time resolved photoluminescence(PL)traces under different excitation powers.Time-dependent electron tra...Dynamic processes of electron transfer by optical doping in monolayer MoSe2 at 6 K are investigated via measuring time resolved photoluminescence(PL)traces under different excitation powers.Time-dependent electron transfer process can be analyzed by a power-law distribution of t^−α withα=0.1-0.24,depending on the laser excitation power.The average electron transfer time of approximately 27.65 s is obtained in the excitation power range of 0.5 to 100μW.As the temperature increases from 20 to 44 K,the energy difference between the neutral and charged excitons is observed to decrease.展开更多
The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and ...The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the ore-forming fluids and the rocks advanced slowly along the permeable strata, and then stratiform skarn and ore bodies concordant with the strata were formed. (3) The gradient transport-reaction taking place across the isotherms in the cross-bedding direction caused the mineralogical composition to alter gradually from magnesian skarn to sulphide ore bodies.展开更多
Shallow gas is considered one of the most serious geological hazards in deepwater drilling because it has the characteristics of suddenness and is difficult to deal with.To perform a quantitative evaluation of shallow...Shallow gas is considered one of the most serious geological hazards in deepwater drilling because it has the characteristics of suddenness and is difficult to deal with.To perform a quantitative evaluation of shallow gas risk during deepwater drilling,a numerical model for calculating gas invasion volume is established based on gas-water two-phase flow theory.The model considers the effect of the dynamic drilling process,and the influencing factors which affect the gas invasion volume are analyzed.Results indicate that the gas invasion rate and accumulated gas invasion volume increase with increasing bottom-hole pressure difference.A linear relationship exists between gas invasion volume and bottom-hole pressure difference.The duration of gas invasion increases as the shallow gas zone thickness increases,and the accumulated gas invasion volume grows as shallow gas zone thickness increases.The increase in formation permeability,water depth,and rate of penetration will enhance the gas invasion rate.However,these three factors can hardly affect the accumulated gas invasion volume.The gas flow rate increases significantly with increasing burial depth of shallow gas.On the basis of influencing factor analysis,a series of methods that consider different risk levels is proposed to control shallow gas,which can provide a reference for the prevention of shallow gas disasters during deepwater drilling.展开更多
Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea,especially submarine landslides,which caused serious damage to marine facilities.The cyclic elastoplastic mo...Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea,especially submarine landslides,which caused serious damage to marine facilities.The cyclic elastoplastic model that can describe the cyclic stress-strain response characteristic for soft clay,is embedded into the coupled Eulerian-Lagrangian(CEL)algorithm of ABAQUS by means of subroutine interface technology.On the basis of CEL technique and undrained cyclic elastoplastic model,a method for analyzing the dynamic instability process of marine slopes under the action of earthquake load is developed.The rationality for cyclic elastoplastic constitutive model is validated by comparing its calculated results with those of von Mises model built in Abaqus.The dynamic instability process of slopes under different conditions are analyzed.The results indicate that the deformation accumulation of soft clay have a significant effect on the dynamic instability process of submarine slopes under earthquake loading.The cumulative deformation is taken into our model and this makes the calculated final deformation of the slope under earthquake load larger than the results of conventional numerical method.When different contact conditions are used for analysis,the smaller the friction coefficient is,the larger the deformation of slopes will be.A numerical analysis method that can both reflect the dynamic properties of soft clay and display the dynamic instability process of submarine landslide is proposed,which could visually predict the topographies of the previous and post failure for submarine slope.展开更多
Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for ana...Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve(DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation(T_(AL)) and the start temperature of eutectic solidification(T_(ES)); double curves method to determine the temperature of the dendrite coherency point of primary austenite(T-(AC)) and the temperature of eutectic cells collision point(T_(EC)); the "technical solidus" method to determine the end temperature of eutectic reaction(T_(EN)). For this purpose, a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction(f_s) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting. Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process(from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting, the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer.展开更多
Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true ...Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true stress-strain curves of the steel were characterized by hardening and subsequent softening and varied with temperatures and strain rates. The hot deformation activation energy of the steel was calculated to be 657.4 k J/mol, which was higher than that of the corresponding wrought steel due to its as-cast coarse columnar grains and heterogeneous structure. Hot processing maps were developed at different plastic strains, which exhibited two domains with peak power dissipation efficiencies at 1150 ℃/0.001 s^（-1） and 1200 ℃/1 s^（-1）, respectively. The corresponding microstructures were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, and electron backscatter diffraction（EBSD）. It has been confirmed that dynamic recrystallization（DRX） controlled by dislocation slipping and climbing mechanism occurs in the temperature and strain rate range of 1050-1200 ℃ and 0.001-0.01 s^（-1）; And DRX controlled by twinning mechanism occurs in the temperature and strain rate range of 1100-1200 ℃, 0.1-1 s^（-1）. These two DRX domains can serve as the hot working windows of the as-cast steel at lower strain rates and at higher strain rates, respectively. The processing maps at different strains also exhibit that the instability region decreases with increasing strain. The corresponding microstructures and the less tensile ductility in the instability region imply that the flow instability is attributed to flow localization accelerated by a few layers of very fine recrystallized grains along the original grain boundaries.展开更多
The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–sol...The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas.Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB（hydroxyl-terminated polybutadiene） hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.展开更多
The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.B...The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.Based on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was reconstructed.It is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate convergence.Future work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.展开更多
The integrative process of a quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and beyond the range of a precursor flow field was simulated numerically. The calculation was based...The integrative process of a quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and beyond the range of a precursor flow field was simulated numerically. The calculation was based on ALE equations and a second-order precision Roe method that adopted chimera grids and a dynamic mesh. From the predicted results, the coupling and interaction among the precursor flow field, propellant gas flow field and high-speed projectile were discussed in detail. The shock-vortex interaction, shockwave reflection, shock-projectile interaction with shock diffraction, and shock focus were clearly demonstrated to explain the effect on the acceleration of the projectile.展开更多
On the basis of analysis the governing process of downstream water level gates AVIO and AVIS, a mathematical model for simulation of dynamic operation process of hydraulically automated irrigation canals instalIed wit...On the basis of analysis the governing process of downstream water level gates AVIO and AVIS, a mathematical model for simulation of dynamic operation process of hydraulically automated irrigation canals instalIed with AVIO and AVIS gates is presented, the main point of this rnathematical model is firstly applying a set of unsteady flow equations （St. Venant equations here） and treating the condition of gate movement as its dynamic boundary, and then deeoupling this interaction of gate movement with the change of canal flow. In this process, it is necessary to give the gateg open-loop transfer function whose input is water level deviation and output is gate discharge. The result of this simulation for a practical reach has shown it has satisfactory accuracy.展开更多
基金supported by the National Natural Science Foundation of China (NSFC) (Grant No. 40802067)the National Basic Research Program of China (973 program, Grant No.2008CB425803)+1 种基金the Basic Scientific Research Operating Expenses of Institute of Geomechanics, CAGS (Grant No. DZLXJK200805)the Land and Natural Resources of China (Grant No. 1212010914025)
文摘Among the geo-hazards caused by the great Wenchuan Earthquake, the rapid and long runout rockslide-debris flow is of primary concern due to the large volume of displaced material and the resultant catastrophic impacts to the landscape and socioeconomic structure. In order to analyze the dynamical process of this kind of geo-hazard, the Donghekou rockslide-debris flow is given as an example in this paper. This event, which killed 780 people, initiated at an elevation of 1300 m with a total long run-out distance of more than 2400 m. The slide mass is mainly composed of dolomite limestone and siliceous limestone of Sinian system, together with carbon slate and phyllite of Cambrian. During the processes from slide initiation to the final cessation of slide movement, five dynamic stages took place, here identified as the initiation stage, the acceleration of movement stage, the air-blast effect stage, the impact and redirection stage and the long runout slidematerial accumulation stage. Field investigations indicate that due to the effects of the earthquake, the dynamics of the Donghekou rockslide-debris flow are apparently controlled by geologic and tectonic conditions, the local geomorphological aspects of the terrain, and the microstructural and macroscopic mechanical properties of rocks which compose the slide mass. These three main factors which dictate the Donghekou rockslide-debris flow dynamics are discussed in detail in this paper, and significant results of field investigations and tests of materials are presented. The above dynamical processes are analyzed in this paper, and some useful conclusions have been gained.
基金supported jointly by the National Key Research and Development Program on Monitoring,Early Warning and Prevention of Major Natural Disaster(2018YFC1506006)the National Natural Science Foundation of China Project(41805054,41875108,41775072,41705065)the SOA International Cooperation Program on Global Change and Air-Sea Interactions(GASI-IPOVAI-03)
文摘The cold tongue mode(CTM),which represents the out-of-phase relationship in sea surface temperature anomaly(SSTA)variability between the Pacific cold tongue region and elsewhere in the tropical Pacific,shows a long-term cooling trend in the eastern equatorial Pacific.In this study,we investigate how well the CTM is reproduced in historical simulations generated by the 20 models considered in Phase 5 of the Coupled Model Intercomparison Project(CMIP5).Qualitatively,all 20 models roughly capture the cooling SSTA associated with the CTM.However,a quantitative assessment(i.e.,Taylor diagrams and the ratio of the trend between the simulations and observations)shows that only five of these 20 models(i.e.,CESM1-CAM5,CMCC-CM,FGOALS-g2,IPSL-CM5B-LR,and NorESM1-M)can reproduce with useful accuracy the spatial pattern and long-term trend of the CTM.We find that these five models generally simulate the main ocean dynamical process associated with the CTM.That is,these models adequately capture the long-term cooling trend in the vertical advection of the anomalous temperature by the mean upwelling.We conclude that the performance of these CMIP5 models,with respect to simulations of the long-term cooling trend associated with the vertical advection,and the related long-term decreasing trend of the vertical gradient of the oceanic temperature anomaly,can play an important role in successful reproduction of the CTM.
基金supported in part by the National Science Fund for Distinguished Young Scholars of China(62225303)the National Natural Science Fundation of China(62303039,62433004)+2 种基金the China Postdoctoral Science Foundation(BX20230034,2023M730190)the Fundamental Research Funds for the Central Universities(buctrc202201,QNTD2023-01)the High Performance Computing Platform,College of Information Science and Technology,Beijing University of Chemical Technology
文摘Data-driven process monitoring is an effective approach to assure safe operation of modern manufacturing and energy systems,such as thermal power plants being studied in this work.Industrial processes are inherently dynamic and need to be monitored using dynamic algorithms.Mainstream dynamic algorithms rely on concatenating current measurement with past data.This work proposes a new,alternative dynamic process monitoring algorithm,using dot product feature analysis(DPFA).DPFA computes the dot product of consecutive samples,thus naturally capturing the process dynamics through temporal correlation.At the same time,DPFA's online computational complexity is lower than not just existing dynamic algorithms,but also classical static algorithms(e.g.,principal component analysis and slow feature analysis).The detectability of the new algorithm is analyzed for three types of faults typically seen in process systems:sensor bias,process fault and gain change fault.Through experiments with a numerical example and real data from a thermal power plant,the DPFA algorithm is shown to be superior to the state-of-the-art methods,in terms of better monitoring performance(fault detection rate and false alarm rate)and lower computational complexity.
基金Project(KKSY201503006)supported by Scientific Research Foundation of Kunming University of Science and Technology,ChinaProject(2014FD009)supported by the Applied Basic Research Foundation(Youth Program)of ChinaProject(51090385)supported by the National Natural Science Foundation of China
文摘The exothermic efficiency of microwave heating an electrolyte/water solution is remarkably high due to the dielectric heating by orientation polarization of water and resistance heating by the Joule process occurred simultaneously compared with pure water.A three-dimensional finite element numerical model of multi-feed microwave heating industrial liquids continuously flowing in a meter-scale circular tube is presented.The temperature field inside the applicator tube in the cavity is solved by COMSOL Multiphysics and professional programming to describe the momentum,energy and Maxwell's equations.The evaluations of the electromagnetic field,the temperature distribution and the velocity field are simulated for the fluids dynamically heated by singleand multi-feed microwave system,respectively.Both the pilot experimental investigations and numerical results of microwave with single-feed heating for fluids with different effective permittivity and flow rates show that the presented numerical modeling makes it possible to analyze dynamic process of multi-feed microwave heating the industrial liquid.The study aids in enhancing the understanding and optimizing of dynamic process in the use of multi-feed microwave heating industrial continuous flow for a variety of material properties and technical parameters.
基金National Natural Science Foundation of China, No.40671186 No.40271012
文摘The western coast of Hainan Island exhibits a savanna landscape. Many types of sand dunes, including transverse dune ridges, longitudinal dune ridges, elliptical dunes, coppice dunes, and climbing dunes, are widely distributed in the coastal zone. In winter, high-frequency and high-energy NE winds （dominant winds） are prevalent, with a resultant drift direction （RDD） of S35.6°W. In spring, low-frequency and low-energy SW secondary winds prevail, with a RDD of N25.1°E. Wind tunnel simulations revealed that the airflow over the dune surface is the main factor controlling the erosion and deposition patterns of dune surfaces and the morphological development of dunes. In the region＇s bidirectional wind environment, with two seasonally distinct energy levels, the airflow over the surface of elliptical dunes, barchan dunes, and transverse dune ridges will exhibit a transverse pattern, whereas the airflow over longitudinal dunes ridges exhibits a lateral pattern and that over climbing dunes exhibits a climbing-circumfluent pattern. These patterns represent different dynamic processes. The coastal dunes on the western coast of Hainan Island are influenced by factors such as onshore winds, sand sources, coastal slopes, rivers, and forest shelter belts. The source of the sand that supplements these dunes particularly influences the development pattern： when there is more sand, the pattern shows positive equilibrium deposition between dune ridges and dunes; otherwise, it shows negative equilibrium deposition. The presence or absence of forest shelter belts also influences deposition and dune development patterns and transformation of dune forms. Coastal dunes and inland desert dunes experience similar dynamic processes, but the former have more diversified shapes and more complex formation mechanisms.
文摘With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process plays the main part in the ozone reduction, but the chemical process partly compensates for the transport process. In the dynamic transport process of ozone, the horizontal transport process plays the main part in the ozone reduction in May, but brings about the ozone increase in June and July. The vertical advective process gradually takes the main role in the ozone reduction in June and July. The effect of convective activities rises gradually so that this effect cannot be overlooked in July, as its magnitude is comparable to that of the net changes. The effect of the gaseous chemical process brings about ozone increases which are more than the net changes sometimes, so the chemical effect is also important.
文摘Abstract The Nansha ultra-crust layer-block is confined by ultra-crustal boundary faults of distinctive features, bordering the Kangtai-Shuangzi-Xiongnan extensional faulted zone on the north, the Baxian-Baram-Yoca-Cuyo nappe faulted zone on the south, the Wan'an-Natuna strike-slip tensional faulted zone on the west and the Mondoro-Panay strike-slip compressive faulted zone on the east. These faults take the top of the Nansha asthenosphere as their common detachmental surface. The Cenozoic dynamic process of the ultra-crust layer-block can be divided into four stages: K2-E21, during which the northern boundary faults extended, this ultra-crust layer-block was separated from the South China-Indosinian continental margin, the Palaeo-South China Sea subducted southwards and the Sibu accretion wedge was formed; E22-E31, during which the Southwest sub-sea basin extended and orogeny was active due to the collision of the Sibu accretion wedge; E32-N11, during which the central sub-sea basin extended, the Miri accretion wedge was formed and “A-type” subduction of the southern margin of the north Balawan occurred; N12-the present, during which large-scale thrusting and napping of the boundary faults in the south and mountain-building have taken place and the South China Sea stopped its extension.
基金National Natural Foundation of China (No.60421002, No.70471052)
文摘Chemical process variables are always driven by random noise and disturbances. The closed-loop con-trol yields process measurements that are auto and cross correlated. The influence of auto and cross correlations on statistical process control (SPC) is investigated in detail by Monte Carlo experiments. It is revealed that in the sense of average performance, the false alarms rates (FAR) of principal component analysis (PCA), dynamic PCA are not affected by the time-series structures of process variables. Nevertheless, non-independent identical distribution will cause the actual FAR to deviate from its theoretic value apparently and result in unexpected consecutive false alarms for normal operating process. Dynamic PCA and ARMA-PCA are demonstrated to be inefficient to remove the influences of auto and cross correlations. Subspace identification-based PCA (SI-PCA) is proposed to improve the monitoring of dynamic processes. Through state space modeling, SI-PCA can remove the auto and cross corre-lations efficiently and avoid consecutive false alarms. Synthetic Monte Carlo experiments and the application in Tennessee Eastman challenge process illustrate the advantages of the proposed approach.
文摘The kinematics and dynamics of plate tectonics are frontal subjects in geosciences and the strong earthquake occurred along the plate boundary result directly from plate movement. By analyzing Ibaraki earthquake sequence, it has been found that the focal fault plane shows a special image of grading expansion along the direction of strike and adjustment along the dip direction respectively. With the consideration of strike, dip and slip directions of focal mechanism, we have confirmed that Ibaraki earthquake belongs to a thrust fault earthquake occurred under the Japan Trench. The cause of the earthquake sequence is discussed in the paper. The study on the temporal-spatial distribution of the earthquake sequence with a time-scale between the year-scale spatial geodetic data and the second-scale moment tensor of the strong earthquake has indicated the dynamic process of Pacific Plate subduction under the Eurasia Plate. According to the average slip distance of earthquake and the velocity of plate movement, it is predicted that a strong earthquake might occur in recent years.
基金Supported by the Natural Science Foundation of Jiangsu Province of China(BK20130531)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD[2011]6)Jiangsu Government Scholarship
文摘The dynamic soft sensor based on a single Gaussian process regression(GPR) model has been developed in fermentation processes.However,limitations of single regression models,for multiphase/multimode fermentation processes,may result in large prediction errors and complexity of the soft sensor.Therefore,a dynamic soft sensor based on Gaussian mixture regression(GMR) was proposed to overcome the problems.Two structure parameters,the number of Gaussian components and the order of the model,are crucial to the soft sensor model.To achieve a simple and effective soft sensor,an iterative strategy was proposed to optimize the two structure parameters synchronously.For the aim of comparisons,the proposed dynamic GMR soft sensor and the existing dynamic GPR soft sensor were both investigated to estimate biomass concentration in a Penicillin simulation process and an industrial Erythromycin fermentation process.Results show that the proposed dynamic GMR soft sensor has higher prediction accuracy and is more suitable for dynamic multiphase/multimode fermentation processes.
基金supported by the National Natural Science Foundation of China under Grant Nos 61674135,11974342 and 61827823.
文摘Dynamic processes of electron transfer by optical doping in monolayer MoSe2 at 6 K are investigated via measuring time resolved photoluminescence(PL)traces under different excitation powers.Time-dependent electron transfer process can be analyzed by a power-law distribution of t^−α withα=0.1-0.24,depending on the laser excitation power.The average electron transfer time of approximately 27.65 s is obtained in the excitation power range of 0.5 to 100μW.As the temperature increases from 20 to 44 K,the energy difference between the neutral and charged excitons is observed to decrease.
基金MGMR Eighth Five- Year Plan Basic Geology Research Foundation Grant 8502216China National Natural Science Foundation Grant 49173169
文摘The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the ore-forming fluids and the rocks advanced slowly along the permeable strata, and then stratiform skarn and ore bodies concordant with the strata were formed. (3) The gradient transport-reaction taking place across the isotherms in the cross-bedding direction caused the mineralogical composition to alter gradually from magnesian skarn to sulphide ore bodies.
基金the Hainan Provincial Natural Science Foundation of China(No.2018CXTD346)the Sanya Yazhou Bay Science and Technology City Program(No.SKJC-2020-01-009)+1 种基金the Hainan Provincial Major Science and Technology Program of China(Nos.521 MS069,ZDKJ202019)the National Key Research and Development Program of China(No.2019YFC0312301)。
文摘Shallow gas is considered one of the most serious geological hazards in deepwater drilling because it has the characteristics of suddenness and is difficult to deal with.To perform a quantitative evaluation of shallow gas risk during deepwater drilling,a numerical model for calculating gas invasion volume is established based on gas-water two-phase flow theory.The model considers the effect of the dynamic drilling process,and the influencing factors which affect the gas invasion volume are analyzed.Results indicate that the gas invasion rate and accumulated gas invasion volume increase with increasing bottom-hole pressure difference.A linear relationship exists between gas invasion volume and bottom-hole pressure difference.The duration of gas invasion increases as the shallow gas zone thickness increases,and the accumulated gas invasion volume grows as shallow gas zone thickness increases.The increase in formation permeability,water depth,and rate of penetration will enhance the gas invasion rate.However,these three factors can hardly affect the accumulated gas invasion volume.The gas flow rate increases significantly with increasing burial depth of shallow gas.On the basis of influencing factor analysis,a series of methods that consider different risk levels is proposed to control shallow gas,which can provide a reference for the prevention of shallow gas disasters during deepwater drilling.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.51179174).
文摘Marine geological disasters occurred frequently in the deep-water slope area of the northern South China Sea,especially submarine landslides,which caused serious damage to marine facilities.The cyclic elastoplastic model that can describe the cyclic stress-strain response characteristic for soft clay,is embedded into the coupled Eulerian-Lagrangian(CEL)algorithm of ABAQUS by means of subroutine interface technology.On the basis of CEL technique and undrained cyclic elastoplastic model,a method for analyzing the dynamic instability process of marine slopes under the action of earthquake load is developed.The rationality for cyclic elastoplastic constitutive model is validated by comparing its calculated results with those of von Mises model built in Abaqus.The dynamic instability process of slopes under different conditions are analyzed.The results indicate that the deformation accumulation of soft clay have a significant effect on the dynamic instability process of submarine slopes under earthquake loading.The cumulative deformation is taken into our model and this makes the calculated final deformation of the slope under earthquake load larger than the results of conventional numerical method.When different contact conditions are used for analysis,the smaller the friction coefficient is,the larger the deformation of slopes will be.A numerical analysis method that can both reflect the dynamic properties of soft clay and display the dynamic instability process of submarine landslide is proposed,which could visually predict the topographies of the previous and post failure for submarine slope.
基金financially supported by the National Development and Reform Commission(2010-324)
文摘Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve(DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation(T_(AL)) and the start temperature of eutectic solidification(T_(ES)); double curves method to determine the temperature of the dendrite coherency point of primary austenite(T-(AC)) and the temperature of eutectic cells collision point(T_(EC)); the "technical solidus" method to determine the end temperature of eutectic reaction(T_(EN)). For this purpose, a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction(f_s) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting. Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process(from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting, the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer.
基金Funded by the National Natural Science Foundation of China(No.51575372)
文摘Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true stress-strain curves of the steel were characterized by hardening and subsequent softening and varied with temperatures and strain rates. The hot deformation activation energy of the steel was calculated to be 657.4 k J/mol, which was higher than that of the corresponding wrought steel due to its as-cast coarse columnar grains and heterogeneous structure. Hot processing maps were developed at different plastic strains, which exhibited two domains with peak power dissipation efficiencies at 1150 ℃/0.001 s^（-1） and 1200 ℃/1 s^（-1）, respectively. The corresponding microstructures were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, and electron backscatter diffraction（EBSD）. It has been confirmed that dynamic recrystallization（DRX） controlled by dislocation slipping and climbing mechanism occurs in the temperature and strain rate range of 1050-1200 ℃ and 0.001-0.01 s^（-1）; And DRX controlled by twinning mechanism occurs in the temperature and strain rate range of 1100-1200 ℃, 0.1-1 s^（-1）. These two DRX domains can serve as the hot working windows of the as-cast steel at lower strain rates and at higher strain rates, respectively. The processing maps at different strains also exhibit that the instability region decreases with increasing strain. The corresponding microstructures and the less tensile ductility in the instability region imply that the flow instability is attributed to flow localization accelerated by a few layers of very fine recrystallized grains along the original grain boundaries.
基金co-supported by the Innovation Foundation of Beihang University for Ph.D. Graduatesthe National Natural Science Foundation of China (No. 51206007)
文摘The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas.Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB（hydroxyl-terminated polybutadiene） hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.
基金Support by the National Natural Science Foundation of China(No.92258303)the Project of Donghai Laboratory(No.DH-2022ZY0005)。
文摘The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical models.Based on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was reconstructed.It is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate convergence.Future work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.
基金the National Key Laboratory of Transient Physics of China
文摘The integrative process of a quiescent projectile accelerated by high-pressure gas to shoot out at a supersonic speed and beyond the range of a precursor flow field was simulated numerically. The calculation was based on ALE equations and a second-order precision Roe method that adopted chimera grids and a dynamic mesh. From the predicted results, the coupling and interaction among the precursor flow field, propellant gas flow field and high-speed projectile were discussed in detail. The shock-vortex interaction, shockwave reflection, shock-projectile interaction with shock diffraction, and shock focus were clearly demonstrated to explain the effect on the acceleration of the projectile.
基金Supported by the 863 Programof China (2001AA242111)
文摘On the basis of analysis the governing process of downstream water level gates AVIO and AVIS, a mathematical model for simulation of dynamic operation process of hydraulically automated irrigation canals instalIed with AVIO and AVIS gates is presented, the main point of this rnathematical model is firstly applying a set of unsteady flow equations （St. Venant equations here） and treating the condition of gate movement as its dynamic boundary, and then deeoupling this interaction of gate movement with the change of canal flow. In this process, it is necessary to give the gateg open-loop transfer function whose input is water level deviation and output is gate discharge. The result of this simulation for a practical reach has shown it has satisfactory accuracy.
