In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The...In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The hollow-roll model has equivalent stiffness of bending resistance and deformation to the real solid and much less meshes,so the computational time is greatly reduced.Based on these,the factors influencing plate profile,such as the roll-bending force,initial crown,thermal crown and heat transfer during rolling and inter-pass cooling can be taken into account in the simulation.The auto mesh-refining module with data passing can automatically refine and re-number elements and transfer the nodal and elemental results to the new meshes.Furthermore,the 3-D modeling routine is parametrically developed and can be run independently of Marc pre-processing program.A seven-pass industrial hot rolling process was continuously simulated to validate the accuracy of model.By comparison of the calculated results with the industrial measured data,the rolling force,temperature and plate profile are in good accordance with the measured ones.展开更多
The fluctuation of a single lake level is a comprehensive reflection of water balance within the basin, while the regional consistent fluctuations of lake level can indicate the change of regional effective moisture. ...The fluctuation of a single lake level is a comprehensive reflection of water balance within the basin, while the regional consistent fluctuations of lake level can indicate the change of regional effective moisture. Previous researches were mainly focused on reconstructing effective moisture by multiproxy analyses of lake sediments. We carried out a series of experiments, including a transient climate evolution model, a lake energy balance model and a lake water balance model to simulate continuous Holocene effective moisture change represented by variability of virtual lake level in East and Central Asia.The virtual lake level, area, water depth and salinity are not equivalent to actual values, but we estimated relative changes of the regional effective moisture. We also explored the driving mechanisms of effective moisture change in different geographical regions. Our results indicated that gradually falling effective moisture during the Holocene in northern China was due to the combined effects of high lake evaporation caused by longwave and shortwave radiation, and low precipitation caused by reductions of summer solar insolation. A decline in effective moisture through the Holocene in the Tibetan Plateau and southern Central Asia resulted from decreased precipitation because of the weakening of the Asian summer monsoon. Increased precipitation induced by the strengthening of the westerly circulation contributed to the effective moisture rise during the Holocene in northern Central Asia.展开更多
In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mech...In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mechanism and flywheel was researched, a design method of transmission parameter optimization was proposed, and the comprehensive matching control strategy was established for the new transmission system. Fuzzy controllers for throttle opening and CVT speed ratio were designed, and power performance and fuel economy of both vehicles respectively equipped with conventional CVT system and new transmission system wrere compared and analyzed by simulation. The results show that power performance and fuel economy of the vehicle equipped with new transmission system are better than that equipped with conventional CVT, thus the rationality of the parameter design method and control algorithm are verified.展开更多
The metallurgical phenomena occurring in the continuous casting mold have a significant influence on the performance and the quality of steel product.The multiphase flow phenomena of molten steel,steel/slag interface ...The metallurgical phenomena occurring in the continuous casting mold have a significant influence on the performance and the quality of steel product.The multiphase flow phenomena of molten steel,steel/slag interface and gas bubbles in the slab continuous casting mold were described by numerical simulation,and the effect of electromagnetic brake（EMBR） and argon gas blowing on the process were investigated.The relationship between wavy fluctuation height near meniscus and the level fluctuation index F,which reflects the situation of mold flux entrapment,was clarified.Moreover,based on a microsegregation model of solute elements in mushy zone with δ/γ transformation and a thermo-mechanical coupling finite element model of shell solidification,the thermal and mechanical behaviors of solidifying shell including the dynamic distribution laws of air gap and mold flux,temperature and stress of shell in slab continuous casting mold were described.展开更多
For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital ...For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital imaging, a simulated annealing algorithm is adopted to expand the meso-structural features of deposit bodies in 3D. The construction of the 3D meso-structure of a deposit body is achieved, and then the particle flow analysis program PFC3 D is used to simulate the mechanical properties of the deposit body. It is shown that with a combination of the simulated annealing algorithm and the statistical feature functions, the randomness and heterogeneity of the rock distribution in the 3D inner structure of deposit body medium can be realized, and the reconstructed structural features of the deposit medium can match the features of the digital images well. The spatial utilizations and the compacting effects of the body-centered cubic, hexagonal close and face-centered packing models are high, so these structures can be applied in the simulations of the deposit structures. However, the shear features of the deposit medium vary depending on the different model constructive modes. Rocks, which are the backbone of the deposit, are the factors that determine the shear strength and deformation modulus of the deposit body. The modeling method proposed is useful for the construction of 3D meso-scope models from 2D meso-scope statistics and can be used for studying the mechanical properties of mixed media, such as deposit bodies.展开更多
Hybrid systems such as Cyber Physical System(CPS)are becoming increasingly popular,mainly due to the involvement of information technology in different aspects of life.For analysis and verification of hybrid system mo...Hybrid systems such as Cyber Physical System(CPS)are becoming increasingly popular,mainly due to the involvement of information technology in different aspects of life.For analysis and verification of hybrid system models,simulation is used extensively.As parts of a common hybrid system may belong to different domains of study,it is sometimes beneficial to use specialized simulation packages(SPs)for each domain.In this case,parts of a system are simulated in different SPs.The idea may seem simple,but coupling more than one simulation component presents challenges related to numerical stability.The presented article suggests an implicit solver coupling technique enhanced to facilitate simulation of hybrid models using multiple simulation components.The technique is developed using two of the most popular simulation interoperability standards,namely,the High Level Architecture and the Functional Mock-up Interface.By using these standards,the developed algorithm will be useful for a large number of practitioners and researchers.The developed algorithm is described using a generic distributed computation model,which makes it reproducible even without using the standards.For the verification of results,the algorithm is tested on two case studies.The results are compared to a monolithic simulator and the proximity of results initiates the validity of the developed algorithm.展开更多
Based on the concept of cloud water resource(CWR)and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences(CAMS),a coupled mesoscale and cloud-resolving model system is developed i...Based on the concept of cloud water resource(CWR)and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences(CAMS),a coupled mesoscale and cloud-resolving model system is developed in the study for CWR numerical quantification(CWR-NQ)in North China for 2017.The results show that(1)the model system is stable and capable for performing 1-yr continuous simulation with a water budget error of less than 0.2%,which indicates a good water balance.(2)Compared with the observational data,it is confirmed that the simulating capability of the CWR-NQ approach is decent for the spatial distribution of yearly cumulative precipitation,daily precipitation intensity,yearly average spatial distribution of water vapor.(3)Compared with the CWR diagnostic quantification(CWR-DQ),the results from the CWR-NQ differ mainly in cloud condensation and cloud evaporation.However,the deviation of the net condensation(condensation minus evaporation)between the two methods is less than 1%.For other composition variables,such as water vapor advection,surface evaporation,precipitation,cloud condensation,and total atmospheric water substances,the relative differences between the CWR-NQ and the CWR-DQ are less than 5%.(4)The spatiotemporal features of the CWR in North China are also studied.The positive correlation between water vapor convergence and precipitation on monthly and seasonal scales,and the lag of precipitation relative to water vapor convergence on hourly and daily scales are analyzed in detail,indicating the significance of the state term on hourly and daily scales.The effects of different spatial scales on the state term,advection term,source-sink term,and total amount are analyzed.It is shown that the advective term varies greatly at different spatiotemporal scales,which leads to differences at different spatiotemporal scales in CWR and related characteristic quantities.展开更多
基金Project(20050248007) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘In order to continuously simulate multi-pass plate rolling process,a 3-D elastic hollow-roll model was proposed and an auto mesh-refining module with data passing was developed and integrated with FE software,Marc.The hollow-roll model has equivalent stiffness of bending resistance and deformation to the real solid and much less meshes,so the computational time is greatly reduced.Based on these,the factors influencing plate profile,such as the roll-bending force,initial crown,thermal crown and heat transfer during rolling and inter-pass cooling can be taken into account in the simulation.The auto mesh-refining module with data passing can automatically refine and re-number elements and transfer the nodal and elemental results to the new meshes.Furthermore,the 3-D modeling routine is parametrically developed and can be run independently of Marc pre-processing program.A seven-pass industrial hot rolling process was continuously simulated to validate the accuracy of model.By comparison of the calculated results with the industrial measured data,the rolling force,temperature and plate profile are in good accordance with the measured ones.
基金supported by the National Natural Science Foundation of China (Grant No. 41822708)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20100102)the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (Grant No. 2019QZKK0202)。
文摘The fluctuation of a single lake level is a comprehensive reflection of water balance within the basin, while the regional consistent fluctuations of lake level can indicate the change of regional effective moisture. Previous researches were mainly focused on reconstructing effective moisture by multiproxy analyses of lake sediments. We carried out a series of experiments, including a transient climate evolution model, a lake energy balance model and a lake water balance model to simulate continuous Holocene effective moisture change represented by variability of virtual lake level in East and Central Asia.The virtual lake level, area, water depth and salinity are not equivalent to actual values, but we estimated relative changes of the regional effective moisture. We also explored the driving mechanisms of effective moisture change in different geographical regions. Our results indicated that gradually falling effective moisture during the Holocene in northern China was due to the combined effects of high lake evaporation caused by longwave and shortwave radiation, and low precipitation caused by reductions of summer solar insolation. A decline in effective moisture through the Holocene in the Tibetan Plateau and southern Central Asia resulted from decreased precipitation because of the weakening of the Asian summer monsoon. Increased precipitation induced by the strengthening of the westerly circulation contributed to the effective moisture rise during the Holocene in northern Central Asia.
基金Project(2011BA3019)supported by the Chongqing Natural Science Foundation,China
文摘In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mechanism and flywheel was researched, a design method of transmission parameter optimization was proposed, and the comprehensive matching control strategy was established for the new transmission system. Fuzzy controllers for throttle opening and CVT speed ratio were designed, and power performance and fuel economy of both vehicles respectively equipped with conventional CVT system and new transmission system wrere compared and analyzed by simulation. The results show that power performance and fuel economy of the vehicle equipped with new transmission system are better than that equipped with conventional CVT, thus the rationality of the parameter design method and control algorithm are verified.
基金Item Sponsored by National Outstanding Young Scientist Foundation of China(50925415)Fundamental Research Funds for Central Universities of China(N100102001)
文摘The metallurgical phenomena occurring in the continuous casting mold have a significant influence on the performance and the quality of steel product.The multiphase flow phenomena of molten steel,steel/slag interface and gas bubbles in the slab continuous casting mold were described by numerical simulation,and the effect of electromagnetic brake（EMBR） and argon gas blowing on the process were investigated.The relationship between wavy fluctuation height near meniscus and the level fluctuation index F,which reflects the situation of mold flux entrapment,was clarified.Moreover,based on a microsegregation model of solute elements in mushy zone with δ/γ transformation and a thermo-mechanical coupling finite element model of shell solidification,the thermal and mechanical behaviors of solidifying shell including the dynamic distribution laws of air gap and mold flux,temperature and stress of shell in slab continuous casting mold were described.
基金Projects(51309089,11202063)supported by the National Natural Science Foundation of ChinaProject(2013BAB06B01)supported by the National High Technology Research and Development Program of China+1 种基金Project(2015CB057903)supported by the National Basic Research Program of ChinaProject(BK20130846)supported by Natural Science Foundation of Jiangsu Province,China
文摘For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital imaging, a simulated annealing algorithm is adopted to expand the meso-structural features of deposit bodies in 3D. The construction of the 3D meso-structure of a deposit body is achieved, and then the particle flow analysis program PFC3 D is used to simulate the mechanical properties of the deposit body. It is shown that with a combination of the simulated annealing algorithm and the statistical feature functions, the randomness and heterogeneity of the rock distribution in the 3D inner structure of deposit body medium can be realized, and the reconstructed structural features of the deposit medium can match the features of the digital images well. The spatial utilizations and the compacting effects of the body-centered cubic, hexagonal close and face-centered packing models are high, so these structures can be applied in the simulations of the deposit structures. However, the shear features of the deposit medium vary depending on the different model constructive modes. Rocks, which are the backbone of the deposit, are the factors that determine the shear strength and deformation modulus of the deposit body. The modeling method proposed is useful for the construction of 3D meso-scope models from 2D meso-scope statistics and can be used for studying the mechanical properties of mixed media, such as deposit bodies.
文摘Hybrid systems such as Cyber Physical System(CPS)are becoming increasingly popular,mainly due to the involvement of information technology in different aspects of life.For analysis and verification of hybrid system models,simulation is used extensively.As parts of a common hybrid system may belong to different domains of study,it is sometimes beneficial to use specialized simulation packages(SPs)for each domain.In this case,parts of a system are simulated in different SPs.The idea may seem simple,but coupling more than one simulation component presents challenges related to numerical stability.The presented article suggests an implicit solver coupling technique enhanced to facilitate simulation of hybrid models using multiple simulation components.The technique is developed using two of the most popular simulation interoperability standards,namely,the High Level Architecture and the Functional Mock-up Interface.By using these standards,the developed algorithm will be useful for a large number of practitioners and researchers.The developed algorithm is described using a generic distributed computation model,which makes it reproducible even without using the standards.For the verification of results,the algorithm is tested on two case studies.The results are compared to a monolithic simulator and the proximity of results initiates the validity of the developed algorithm.
基金Supported by the National Key Research and Development Program of China(2016YFA0601701)National Natural Science Foundation of China(42075191)National High Technology Research and Development Program of China(2012AA120902).
文摘Based on the concept of cloud water resource(CWR)and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences(CAMS),a coupled mesoscale and cloud-resolving model system is developed in the study for CWR numerical quantification(CWR-NQ)in North China for 2017.The results show that(1)the model system is stable and capable for performing 1-yr continuous simulation with a water budget error of less than 0.2%,which indicates a good water balance.(2)Compared with the observational data,it is confirmed that the simulating capability of the CWR-NQ approach is decent for the spatial distribution of yearly cumulative precipitation,daily precipitation intensity,yearly average spatial distribution of water vapor.(3)Compared with the CWR diagnostic quantification(CWR-DQ),the results from the CWR-NQ differ mainly in cloud condensation and cloud evaporation.However,the deviation of the net condensation(condensation minus evaporation)between the two methods is less than 1%.For other composition variables,such as water vapor advection,surface evaporation,precipitation,cloud condensation,and total atmospheric water substances,the relative differences between the CWR-NQ and the CWR-DQ are less than 5%.(4)The spatiotemporal features of the CWR in North China are also studied.The positive correlation between water vapor convergence and precipitation on monthly and seasonal scales,and the lag of precipitation relative to water vapor convergence on hourly and daily scales are analyzed in detail,indicating the significance of the state term on hourly and daily scales.The effects of different spatial scales on the state term,advection term,source-sink term,and total amount are analyzed.It is shown that the advective term varies greatly at different spatiotemporal scales,which leads to differences at different spatiotemporal scales in CWR and related characteristic quantities.
