Coal is a solid combustible mineral,and coal-bearing strata have important hydrocarbon generation potential and contribute to more than 12%of the global hydrocarbon resources.However,the deposition and hydrocarbon evo...Coal is a solid combustible mineral,and coal-bearing strata have important hydrocarbon generation potential and contribute to more than 12%of the global hydrocarbon resources.However,the deposition and hydrocarbon evolution process of ancient coal-bearing strata is characterized by multiple geological times,leading to obvious distinctions in their hydrocarbon generation potential,geological processes,and production,which affect the evaluation and exploration of hydrocarbon resources derived from coaly source rocks worldwide.This study aimed to identify the differences on oil-generated parent macerals and the production of oil generated from different coaly source rocks and through different oil generation processes.Integrating with the analysis of previous tectonic burial history and hydrocarbon generation history,high-temperature and high-pressure thermal simulation experiments,organic geochemistry,and organic petrology were performed on the Carboniferous-Permian(C-P)coaly source rocks in the Huanghua Depression,Bohai Bay Basin.The oil-generated parent macerals of coal's secondary oil generation process(SOGP)were mainly hydrogen-rich collotelinite,collodetrinite,sporinite,and cutinite,while the oil-generated parent macerals of tertiary oil generation process(TOGP)were the remaining small amount of hydrogen-rich collotelinite,sporinite,and cutinite,as well as dispersed soluble organic matter and unexhausted residual hydrocarbons.Compared with coal,the oil-generated parent macerals of coaly shale SOGP were mostly sporinite and cutinite.And part of hydrogen-poor vitrinite,lacking hydrocarbon-rich macerals,and macerals of the TOGP,in addition to some remaining cutinite and a small amount of crude oil and bitumen from SOGP contributed to the oil yield.The results indicated that the changes in oil yield had a good junction between SOGP and TOGP,both coal and coaly shale had higher SOGP aborted oil yield than TOGP starting yield,and coaly shale TOGP peak oil yield was lower than SOGP peak oil yield.There were significant differences in saturated hydrocarbon and aromatic parameters in coal and coaly shale.Coal SOGP was characterized by a lower Ts/Tm and C31-homohopane22S/(22S+22R)and a higher Pr/n C17compared to coal TOGP,while the aromatic parameter methyl dibenzothiophene ratio(MDR)exhibited coaly shale TOGP was higher than coaly shale SOGP than coaly TOGP than coaly SOGP,and coal trimethylnaphthalene ratio(TNR)was lower than coaly shale TNR.Thus,we established oil generation processes and discriminative plates.In this way,we distinguished the differences between oil generation parent maceral,oil generation time,and oil production of coaly source rocks,and therefore,we provided important support for the evaluation,prediction,and exploration of oil resources from global ancient coaly source rocks.展开更多
Hybrid simulation can be a cost effective approach for dynamic testing of structural components at full scale while capturing the system level response through interactions with a numerical model.The dynamic response ...Hybrid simulation can be a cost effective approach for dynamic testing of structural components at full scale while capturing the system level response through interactions with a numerical model.The dynamic response of a seismically isolated structure depends on the combined characteristics of the ground motion,bearings,and superstructure.Therefore,dynamic full-scale system level tests of isolated structures under realistic dynamic loading conditions are desirable towards a holistic validation of this earthquake protection strategy.Moreover,bearing properties and their ultimate behavior have been shown to be highly dependent on rate-of-loading and scale size effects,especially under extreme loading conditions.Few laboratory facilities can test full-scale seismic isolation bearings under prescribed displacement and/or loading protocols.The adaptation of a full-scale bearing test machine for the implementation of real-time hybrid simulation is presented here with a focus on the challenges encountered in attaining reliable simulation results for large scale dynamic tests.These advanced real-time hybrid simulations of large and complex hybrid models with several thousands of degrees of freedom are some of the first to use high performance parallel computing to rapidly execute the numerical analyses.Challenges in the experimental setup included measured forces contaminated by delay and other systematic control errors in applying desired displacements.Friction and inertial forces generated by the large-scale loading apparatus can affect the accuracy of measured force feedbacks.Reliable results from real-time hybrid simulation requires implementation of compensation algorithms and correction of these various sources of errors.Overall,this research program confirms that real-time hybrid simulation is a viable testing method to experimentally assess the behavior of full-scale isolators while capturing interactions with the numerical models of the superstructure to evaluate system level and in-structure response.展开更多
Hydrogenated microcrystalline silicon （~c-Si：H） films with a high deposition rate of 1.2nm/s were prepared by hot-wire chemical vapor deposition （HWCVD）. The growth-front roughening processes of the μc-Si..H fil...Hydrogenated microcrystalline silicon （~c-Si：H） films with a high deposition rate of 1.2nm/s were prepared by hot-wire chemical vapor deposition （HWCVD）. The growth-front roughening processes of the μc-Si..H films were investi- gated by atomic force microscopy. According to the scaling theory, the growth exponent β≈0.67, the roughness exponent α≈0.80,and the dynamic exponent 1/z = 0.40 are obtained. These scaling exponents cannot be explained well by the known growth models. An attempt at Monte Carlo simulation has been made to describe the growth process of μc-Si： H film using a particle reemission model where the incident flux distribution,the type and concentration of growth radical, and sticking,reemission,shadowing mechanisms all contributed to the growing morphology.展开更多
Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing...Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing efficiency in large-scale channel. A 3D spiral baffle structure(3SBS) was designed and optimized to form microfluidic field disturbed by continuous secondary flow in millimeter scale Y-shaped tube mixer(YSTM). Enhancement effect of the 3SBS in liquid-liquid homogeneous chemical processes was verified and evaluated through the combination of simulation and experiment. Compared with 1 mm YSTM, 10 mm YSTM with 3SBS increased the treatment capacity by 100 times, shortened the basic complete mixing time by 0.85 times, which proves the potential of microfluidic field strategy in enhancement and scale-up of liquid-liquid homogeneous chemical process.展开更多
The energy contents of biogas could be significantly enhanced by upgrading it to vehicle fuel quality.A pilot-scale separation plant based on carbon hollow fiber membranes for upgrading biogas to vehicle fuel quality ...The energy contents of biogas could be significantly enhanced by upgrading it to vehicle fuel quality.A pilot-scale separation plant based on carbon hollow fiber membranes for upgrading biogas to vehicle fuel quality was constructed and operated at the biogas plant,Gl?r IKS,Lillehammer Norway.Vehicle fuel quality according to Swedish legislation was successfully achieved in a single stage separation process.The raw biogas from anaerobic digestion of food waste contained 64±3 mol%CH_4,30–35 mol%CO_2 and less than one percent of N_2 and a minor amount of other impurities.The raw biogas was available at 1.03 bar with a maximum flow rate of 60 Nm^3h^(à1).Pre-treatment of biogas was performed to remove bulk H_2O and H_2S contents up to the required limits in the vehicle fuel before entering to membrane system.The membrane separation plant was designed to process 60 Nm^3h^(à1)of raw biogas at pressure up to 21 bar.The initial tests were,however,performed for the feed flow rate of 10 Nm^3h^(à1)at 21 bar.The successful operation of the pilot plant separation was continuously run for 192 h(8days).The CH_4 purity of 96%and maximum CH_4 recovery of 98%was reached in a short-term test of 5 h.The permeate stream contained over20 mol%CH_4which could be used for the heating application.Aspen Hysys~?was integrated with Chem Brane(in-house developed membrane model)to run the simulations for estimation of membrane area and energy requirement of the pilot plant.Cost estimation was performed based on simulation data and later compared with actual field results.展开更多
The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies root...The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people’s understanding and cognition to driving forces of regional LUC. Biophysical driving forces are relatively stable, and have the cumulating effects. Human driving forces are relatively active, and are main driving forces of short-term regional LUC. Existing regional LUC models can answer the three main problems: which contribution (why), which location (where) and what rate (when). But, regional land use system is defined as the self-organized system, usually affected by the cri- tical value area and sudden change, and controlled by different stages. To reduce the impact of critical threshold and break on land use system, the studies of LUC driving forces will aim at following priority areas: data linkage between remote sensing and no-remote sensing data; underlying driving force identification; driving factor quantification; driving factor scale dependence; and driving process integration simulation.展开更多
The effects of different convective parameterization,explicit moisture schemes and surface heat- ing on the meso-β scale structure of a squall line system are investigated,by using an improved mesoscale model.It is f...The effects of different convective parameterization,explicit moisture schemes and surface heat- ing on the meso-β scale structure of a squall line system are investigated,by using an improved mesoscale model.It is found that the successful prediction of mesoscale convective systems hinges up- on not only the sub-grid scale convection,but also the resolvable scale phase change processes and the diurnal variation in the boundary layer.The simultaneous operation of the Fritsch-Chappell convective scheme with parameterized moist downdrafts and the prognostic equations for cloud water (ice) and rainwater (snow) seems to be essential in simulating realistically MCSs and reducing or eliminating the unrealistic development of the CISK-like instability associated with the squall line system.展开更多
脱丁烷塔聚合物结垢问题是制约乙烯装置长周期运行的主要因素之一。目前新建装置通过降低操作压力在防止脱丁烷塔聚合物结垢方面取得了显著效果。以脱丁烷塔为例,对降压过程的可行性、经济性以及风险点进行分析和总结,利用化工流程模拟...脱丁烷塔聚合物结垢问题是制约乙烯装置长周期运行的主要因素之一。目前新建装置通过降低操作压力在防止脱丁烷塔聚合物结垢方面取得了显著效果。以脱丁烷塔为例,对降压过程的可行性、经济性以及风险点进行分析和总结,利用化工流程模拟软件Aspen Plus对降压后各项工艺参数进行模拟优化,将优化结果应用于实际生产过程。结果表明,脱丁烷塔的降压极限为350 kPa,降压后全塔温度降低约4℃,塔釜粗裂解汽油中的C_(4)摩尔分数降低0.32百分点,节省低压蒸汽1.3 t h,装置能耗和C_(4)产品损失降低,循环水侧压降、循环水在换热器内的流速和对数传热温差均在合理范围之内。展开更多
The metal cutting process is accompanied by complex stress field,strain field,temperature field.The comprehensive effects of process parameters on chip morphology,cutting force,tool wear and residual stress are comple...The metal cutting process is accompanied by complex stress field,strain field,temperature field.The comprehensive effects of process parameters on chip morphology,cutting force,tool wear and residual stress are complex and inter-connected.Finite element method(FEM)is considered as an effective method to predict process variables and reveal microscopic physical phenomena in the cutting process.Therefore,the finite element(FE)simulation is used to research the conventional and micro scale cutting process,and the differences in the establishment of process variable FE simulation models are distinguished,thereby improving the accuracy of FE simulation.The reliability and effectiveness of FE simulation model largely depend on the accuracy of the simulation method,constitutive model,friction model,damage model in describing mesh element,the dynamic mechanical behavior of materials,the tool-chip-workpiece contact process and the chip formation mechanism.In this paper,the FE models of conventional and micro process variables are comprehensively and up-to-date reviewed for different materials and machining methods.The purpose is to establish a FE model that is more in line with the real cutting conditions,and to provide the possibility for optimizing the cutting process variables.The development direction of FE simulation of metal cutting process is discussed,which provides guidance for future cutting process modeling.展开更多
Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by usin...Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.展开更多
The multi-scale structures of complex flows have been great challenges to both theoretical and engineer-ing researches, and multi-scale modeling is the natural way in response. Particle methods (PMs) are ideal constit...The multi-scale structures of complex flows have been great challenges to both theoretical and engineer-ing researches, and multi-scale modeling is the natural way in response. Particle methods (PMs) are ideal constitutors and powerful probes of multi-scale models, owing to their physical insight and computational simplicity. In this paper, the role of different PMs for multi-scale modeling of complex flows is critically reviewed and possible development of PMs in this background is prospected, with the emphasis on pseudo-particle modeling (PPM). The performances of some different PMs are compared in simulations and new devel-opment in the fundamentals and applications of PPM is also reported, demonstrating PPM as a unique PM for multi-scale modeling.展开更多
Land-use change simulation for large-scale regions(i.e.provincial regions or countries) is very useful for many global studies.Such simulation,however,is affected by computational capability of general computers.This ...Land-use change simulation for large-scale regions(i.e.provincial regions or countries) is very useful for many global studies.Such simulation,however,is affected by computational capability of general computers.This paper proposes a method to implement cellular automata(CA) for land use change simulation based on graphics processing units(GPUs).This method can be applied to large-scale land-use change simulations by combining the latest GPU high-performance computing technology and CA.We carried out the experiments by simulating land-use change processes at a provincial scale.This involves a lot of sophisticated techniques,such as model mapping,and computational procedure of GPU-CA model.This proposed model has been validated by land-use change simulation in Guangdong Province,China.The comparison indicates that the GPU-CA model is faster than traditional CA by 30 times.Such improvement is crucial for land-use change simulations in provincial regions and countries.The outputs of the simulation can be further used to provide information to other global change models.展开更多
基金supported by the Certificate of National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2016ZX05006007-004)the National Natural Science Foundation of China(Nos.42172145,42072130)。
文摘Coal is a solid combustible mineral,and coal-bearing strata have important hydrocarbon generation potential and contribute to more than 12%of the global hydrocarbon resources.However,the deposition and hydrocarbon evolution process of ancient coal-bearing strata is characterized by multiple geological times,leading to obvious distinctions in their hydrocarbon generation potential,geological processes,and production,which affect the evaluation and exploration of hydrocarbon resources derived from coaly source rocks worldwide.This study aimed to identify the differences on oil-generated parent macerals and the production of oil generated from different coaly source rocks and through different oil generation processes.Integrating with the analysis of previous tectonic burial history and hydrocarbon generation history,high-temperature and high-pressure thermal simulation experiments,organic geochemistry,and organic petrology were performed on the Carboniferous-Permian(C-P)coaly source rocks in the Huanghua Depression,Bohai Bay Basin.The oil-generated parent macerals of coal's secondary oil generation process(SOGP)were mainly hydrogen-rich collotelinite,collodetrinite,sporinite,and cutinite,while the oil-generated parent macerals of tertiary oil generation process(TOGP)were the remaining small amount of hydrogen-rich collotelinite,sporinite,and cutinite,as well as dispersed soluble organic matter and unexhausted residual hydrocarbons.Compared with coal,the oil-generated parent macerals of coaly shale SOGP were mostly sporinite and cutinite.And part of hydrogen-poor vitrinite,lacking hydrocarbon-rich macerals,and macerals of the TOGP,in addition to some remaining cutinite and a small amount of crude oil and bitumen from SOGP contributed to the oil yield.The results indicated that the changes in oil yield had a good junction between SOGP and TOGP,both coal and coaly shale had higher SOGP aborted oil yield than TOGP starting yield,and coaly shale TOGP peak oil yield was lower than SOGP peak oil yield.There were significant differences in saturated hydrocarbon and aromatic parameters in coal and coaly shale.Coal SOGP was characterized by a lower Ts/Tm and C31-homohopane22S/(22S+22R)and a higher Pr/n C17compared to coal TOGP,while the aromatic parameter methyl dibenzothiophene ratio(MDR)exhibited coaly shale TOGP was higher than coaly shale SOGP than coaly TOGP than coaly SOGP,and coal trimethylnaphthalene ratio(TNR)was lower than coaly shale TNR.Thus,we established oil generation processes and discriminative plates.In this way,we distinguished the differences between oil generation parent maceral,oil generation time,and oil production of coaly source rocks,and therefore,we provided important support for the evaluation,prediction,and exploration of oil resources from global ancient coaly source rocks.
文摘Hybrid simulation can be a cost effective approach for dynamic testing of structural components at full scale while capturing the system level response through interactions with a numerical model.The dynamic response of a seismically isolated structure depends on the combined characteristics of the ground motion,bearings,and superstructure.Therefore,dynamic full-scale system level tests of isolated structures under realistic dynamic loading conditions are desirable towards a holistic validation of this earthquake protection strategy.Moreover,bearing properties and their ultimate behavior have been shown to be highly dependent on rate-of-loading and scale size effects,especially under extreme loading conditions.Few laboratory facilities can test full-scale seismic isolation bearings under prescribed displacement and/or loading protocols.The adaptation of a full-scale bearing test machine for the implementation of real-time hybrid simulation is presented here with a focus on the challenges encountered in attaining reliable simulation results for large scale dynamic tests.These advanced real-time hybrid simulations of large and complex hybrid models with several thousands of degrees of freedom are some of the first to use high performance parallel computing to rapidly execute the numerical analyses.Challenges in the experimental setup included measured forces contaminated by delay and other systematic control errors in applying desired displacements.Friction and inertial forces generated by the large-scale loading apparatus can affect the accuracy of measured force feedbacks.Reliable results from real-time hybrid simulation requires implementation of compensation algorithms and correction of these various sources of errors.Overall,this research program confirms that real-time hybrid simulation is a viable testing method to experimentally assess the behavior of full-scale isolators while capturing interactions with the numerical models of the superstructure to evaluate system level and in-structure response.
文摘Hydrogenated microcrystalline silicon （~c-Si：H） films with a high deposition rate of 1.2nm/s were prepared by hot-wire chemical vapor deposition （HWCVD）. The growth-front roughening processes of the μc-Si..H films were investi- gated by atomic force microscopy. According to the scaling theory, the growth exponent β≈0.67, the roughness exponent α≈0.80,and the dynamic exponent 1/z = 0.40 are obtained. These scaling exponents cannot be explained well by the known growth models. An attempt at Monte Carlo simulation has been made to describe the growth process of μc-Si： H film using a particle reemission model where the incident flux distribution,the type and concentration of growth radical, and sticking,reemission,shadowing mechanisms all contributed to the growing morphology.
基金supported by the National Key Research and Development Program of China (2021YFC2101900 and 2019YFA0905000)National Natural Science Foundation of China (21908094, 21776130 and 22078150)+1 种基金Nanjing International Joint Research and Development Project (202002037)Top-notch Academic Programs Project of Jiangsu Higher Education Institutions。
文摘Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing efficiency in large-scale channel. A 3D spiral baffle structure(3SBS) was designed and optimized to form microfluidic field disturbed by continuous secondary flow in millimeter scale Y-shaped tube mixer(YSTM). Enhancement effect of the 3SBS in liquid-liquid homogeneous chemical processes was verified and evaluated through the combination of simulation and experiment. Compared with 1 mm YSTM, 10 mm YSTM with 3SBS increased the treatment capacity by 100 times, shortened the basic complete mixing time by 0.85 times, which proves the potential of microfluidic field strategy in enhancement and scale-up of liquid-liquid homogeneous chemical process.
文摘The energy contents of biogas could be significantly enhanced by upgrading it to vehicle fuel quality.A pilot-scale separation plant based on carbon hollow fiber membranes for upgrading biogas to vehicle fuel quality was constructed and operated at the biogas plant,Gl?r IKS,Lillehammer Norway.Vehicle fuel quality according to Swedish legislation was successfully achieved in a single stage separation process.The raw biogas from anaerobic digestion of food waste contained 64±3 mol%CH_4,30–35 mol%CO_2 and less than one percent of N_2 and a minor amount of other impurities.The raw biogas was available at 1.03 bar with a maximum flow rate of 60 Nm^3h^(à1).Pre-treatment of biogas was performed to remove bulk H_2O and H_2S contents up to the required limits in the vehicle fuel before entering to membrane system.The membrane separation plant was designed to process 60 Nm^3h^(à1)of raw biogas at pressure up to 21 bar.The initial tests were,however,performed for the feed flow rate of 10 Nm^3h^(à1)at 21 bar.The successful operation of the pilot plant separation was continuously run for 192 h(8days).The CH_4 purity of 96%and maximum CH_4 recovery of 98%was reached in a short-term test of 5 h.The permeate stream contained over20 mol%CH_4which could be used for the heating application.Aspen Hysys~?was integrated with Chem Brane(in-house developed membrane model)to run the simulations for estimation of membrane area and energy requirement of the pilot plant.Cost estimation was performed based on simulation data and later compared with actual field results.
基金Under the auspices of the National Natural Science Foundation of China (No. 49771073) and Key Project of ChineseAcademy of Sciences (No. KZ952-J1-203)
文摘The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people’s understanding and cognition to driving forces of regional LUC. Biophysical driving forces are relatively stable, and have the cumulating effects. Human driving forces are relatively active, and are main driving forces of short-term regional LUC. Existing regional LUC models can answer the three main problems: which contribution (why), which location (where) and what rate (when). But, regional land use system is defined as the self-organized system, usually affected by the cri- tical value area and sudden change, and controlled by different stages. To reduce the impact of critical threshold and break on land use system, the studies of LUC driving forces will aim at following priority areas: data linkage between remote sensing and no-remote sensing data; underlying driving force identification; driving factor quantification; driving factor scale dependence; and driving process integration simulation.
文摘The effects of different convective parameterization,explicit moisture schemes and surface heat- ing on the meso-β scale structure of a squall line system are investigated,by using an improved mesoscale model.It is found that the successful prediction of mesoscale convective systems hinges up- on not only the sub-grid scale convection,but also the resolvable scale phase change processes and the diurnal variation in the boundary layer.The simultaneous operation of the Fritsch-Chappell convective scheme with parameterized moist downdrafts and the prognostic equations for cloud water (ice) and rainwater (snow) seems to be essential in simulating realistically MCSs and reducing or eliminating the unrealistic development of the CISK-like instability associated with the squall line system.
文摘脱丁烷塔聚合物结垢问题是制约乙烯装置长周期运行的主要因素之一。目前新建装置通过降低操作压力在防止脱丁烷塔聚合物结垢方面取得了显著效果。以脱丁烷塔为例,对降压过程的可行性、经济性以及风险点进行分析和总结,利用化工流程模拟软件Aspen Plus对降压后各项工艺参数进行模拟优化,将优化结果应用于实际生产过程。结果表明,脱丁烷塔的降压极限为350 kPa,降压后全塔温度降低约4℃,塔釜粗裂解汽油中的C_(4)摩尔分数降低0.32百分点,节省低压蒸汽1.3 t h,装置能耗和C_(4)产品损失降低,循环水侧压降、循环水在换热器内的流速和对数传热温差均在合理范围之内。
基金supported by the National Natural Science Foundation of China(No.52175393)。
文摘The metal cutting process is accompanied by complex stress field,strain field,temperature field.The comprehensive effects of process parameters on chip morphology,cutting force,tool wear and residual stress are complex and inter-connected.Finite element method(FEM)is considered as an effective method to predict process variables and reveal microscopic physical phenomena in the cutting process.Therefore,the finite element(FE)simulation is used to research the conventional and micro scale cutting process,and the differences in the establishment of process variable FE simulation models are distinguished,thereby improving the accuracy of FE simulation.The reliability and effectiveness of FE simulation model largely depend on the accuracy of the simulation method,constitutive model,friction model,damage model in describing mesh element,the dynamic mechanical behavior of materials,the tool-chip-workpiece contact process and the chip formation mechanism.In this paper,the FE models of conventional and micro process variables are comprehensively and up-to-date reviewed for different materials and machining methods.The purpose is to establish a FE model that is more in line with the real cutting conditions,and to provide the possibility for optimizing the cutting process variables.The development direction of FE simulation of metal cutting process is discussed,which provides guidance for future cutting process modeling.
基金co-supported by China Postdoctoral Science Foundation (20090461314)
文摘Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.
基金the National Natural Science Foundation of China(Grant Nos.20336040 , 20490201)the Chinese Academy of Sciences(Grant No.INF105-SCE-2-07).
文摘The multi-scale structures of complex flows have been great challenges to both theoretical and engineer-ing researches, and multi-scale modeling is the natural way in response. Particle methods (PMs) are ideal constitutors and powerful probes of multi-scale models, owing to their physical insight and computational simplicity. In this paper, the role of different PMs for multi-scale modeling of complex flows is critically reviewed and possible development of PMs in this background is prospected, with the emphasis on pseudo-particle modeling (PPM). The performances of some different PMs are compared in simulations and new devel-opment in the fundamentals and applications of PPM is also reported, demonstrating PPM as a unique PM for multi-scale modeling.
基金supported by the Key National Natural Science Foundation of China (40830532)the National Natural Science Foundation of China (40901187 and 41171308)
文摘Land-use change simulation for large-scale regions(i.e.provincial regions or countries) is very useful for many global studies.Such simulation,however,is affected by computational capability of general computers.This paper proposes a method to implement cellular automata(CA) for land use change simulation based on graphics processing units(GPUs).This method can be applied to large-scale land-use change simulations by combining the latest GPU high-performance computing technology and CA.We carried out the experiments by simulating land-use change processes at a provincial scale.This involves a lot of sophisticated techniques,such as model mapping,and computational procedure of GPU-CA model.This proposed model has been validated by land-use change simulation in Guangdong Province,China.The comparison indicates that the GPU-CA model is faster than traditional CA by 30 times.Such improvement is crucial for land-use change simulations in provincial regions and countries.The outputs of the simulation can be further used to provide information to other global change models.
