Large eddy simulation （LES） using the Smagorinsky eddy viscosity model is added to the two-dimensional nine velocity components （D2Q9） lattice Boltzmann equation （LBE） with multi-relaxation-time （MRT） to simul...Large eddy simulation （LES） using the Smagorinsky eddy viscosity model is added to the two-dimensional nine velocity components （D2Q9） lattice Boltzmann equation （LBE） with multi-relaxation-time （MRT） to simulate incompressible turbulent cavity flows with the Reynolds numbers up to 1 × 10^7. To improve the computation efficiency of LBM on the numerical simulations of turbulent flows, the massively parallel computing power from a graphic processing unit （GPU） with a computing unified device architecture （CUDA） is introduced into the MRT-LBE-LES model. The model performs well, compared with the results from others, with an increase of 76 times in computation efficiency. It appears that the higher the Reynolds numbers is, the smaller the Smagorinsky constant should be, if the lattice number is fixed. Also, for a selected high Reynolds number and a selected proper Smagorinsky constant, there is a minimum requirement for the lattice number so that the Smagorinsky eddy viscosity will not be excessively large.展开更多
Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagati...Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagation were predicted by the relationship between temperature,shrinkage force and solidification time during the casting solidification process.The reliability and practicability of the multichannel"cross"hot tearing device were verified by casting experiments and numerical simulations.The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order:2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670°C and a mold temperature of 25°C.Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing.The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging.展开更多
With the continuous scaling in conventional CMOS technologies,the planar MOSFET device is limited by the severe short-channel-effect(SCE),Multi-gate FETs(MuG-FET)such as FinFETs and Nanowire,Nanosheet devices have eme...With the continuous scaling in conventional CMOS technologies,the planar MOSFET device is limited by the severe short-channel-effect(SCE),Multi-gate FETs(MuG-FET)such as FinFETs and Nanowire,Nanosheet devices have emerged as the most promising candidates to extend the CMOS scaling beyond sub-22 nm node.The multi-gate structure has better short channel behaviors due to enhanced control from the multiple gates.Due to the relatively more mature process and rich learning of the device physics,the FinFET is still extended to 5 nm technology node.In this paper,we proposed a 5 nm FINFET device,which is based on typical 5 nm logic design rules.To achieve the challenging device performance target,which is around 15%speed gain or 25%power reduction against the 7 nm device,we have performed an optimization on the process parameters and iterate through device simulation with the consideration of current process capability.Based on our preferred device architecture,we provide our brief process flow,key dimensions,and simulated device DC/AC performance,like Vt,Idsat,SS,DIBL and parasitic parameters.As a part of the final evaluation,RO simulation result has been checked,which demonstrates that the Performance Per Area(PPA)is close to industry reference 5 nm performance.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
基金supported by College of William and Mary,Virginia Institute of Marine Science for the study environment
文摘Large eddy simulation （LES） using the Smagorinsky eddy viscosity model is added to the two-dimensional nine velocity components （D2Q9） lattice Boltzmann equation （LBE） with multi-relaxation-time （MRT） to simulate incompressible turbulent cavity flows with the Reynolds numbers up to 1 × 10^7. To improve the computation efficiency of LBM on the numerical simulations of turbulent flows, the massively parallel computing power from a graphic processing unit （GPU） with a computing unified device architecture （CUDA） is introduced into the MRT-LBE-LES model. The model performs well, compared with the results from others, with an increase of 76 times in computation efficiency. It appears that the higher the Reynolds numbers is, the smaller the Smagorinsky constant should be, if the lattice number is fixed. Also, for a selected high Reynolds number and a selected proper Smagorinsky constant, there is a minimum requirement for the lattice number so that the Smagorinsky eddy viscosity will not be excessively large.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51875365).
文摘Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagation were predicted by the relationship between temperature,shrinkage force and solidification time during the casting solidification process.The reliability and practicability of the multichannel"cross"hot tearing device were verified by casting experiments and numerical simulations.The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order:2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670°C and a mold temperature of 25°C.Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing.The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging.
基金The authors would like to thank the management team and all our team members in Shanghai ICRD center.
文摘With the continuous scaling in conventional CMOS technologies,the planar MOSFET device is limited by the severe short-channel-effect(SCE),Multi-gate FETs(MuG-FET)such as FinFETs and Nanowire,Nanosheet devices have emerged as the most promising candidates to extend the CMOS scaling beyond sub-22 nm node.The multi-gate structure has better short channel behaviors due to enhanced control from the multiple gates.Due to the relatively more mature process and rich learning of the device physics,the FinFET is still extended to 5 nm technology node.In this paper,we proposed a 5 nm FINFET device,which is based on typical 5 nm logic design rules.To achieve the challenging device performance target,which is around 15%speed gain or 25%power reduction against the 7 nm device,we have performed an optimization on the process parameters and iterate through device simulation with the consideration of current process capability.Based on our preferred device architecture,we provide our brief process flow,key dimensions,and simulated device DC/AC performance,like Vt,Idsat,SS,DIBL and parasitic parameters.As a part of the final evaluation,RO simulation result has been checked,which demonstrates that the Performance Per Area(PPA)is close to industry reference 5 nm performance.
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.
