The carbon diffusivity in tungsten is one fundamental and essential factor in the application of tungsten as plasmafacing materials for fusion reactors and substrates for diamond growth. However, data on this are quit...The carbon diffusivity in tungsten is one fundamental and essential factor in the application of tungsten as plasmafacing materials for fusion reactors and substrates for diamond growth. However, data on this are quite scarce and largely scattered. We perform a series of first-principles calculations to predict the diffusion parameters of carbon in tungsten,and evaluate the effect of temperature on them by introducing lattice expansion and phonon vibration. The carbon atom prefers to occupy octahedral interstitial site rather than tetrahedral interstitial site, and the minimum energy path for its diffusion goes through a tetrahedral site. The temperature has little effect on the pre-exponential factor but a marked effect on the activation energy, which linearly increases with the temperature. Our predicted results are well consistent with the experimental data obtained at high temperature(>1800 K) but significantly larger than the experimental results at low temperature(<1800 K).展开更多
The interactions of solute atoms with vacancies play a key role in diffusion and precipitation of alloying elements,ultimately influencing the mechanical properties of aluminum alloys.In this study,first-principles ca...The interactions of solute atoms with vacancies play a key role in diffusion and precipitation of alloying elements,ultimately influencing the mechanical properties of aluminum alloys.In this study,first-principles calculations are systematically performed to quantify the solute–vacancy interactions for the 3d–4p series and the 4d–5p series.The solute–vacancy interaction gradually transforms from repulsion to attraction from left to right.The solute–vacancy binding energy is sensitive to the supercell size for elements at the beginning.These behaviors of the solute–vacancy binding energy can be understood in terms of the combination and competition between the elastic and electronic interactions.Overall,the electronic binding energy follows a similar trend to the total binding energy and plays a major role in the solute–vacancy interactions.展开更多
The control design problem plays a fundamental role in the study of logical control networks(LCNs).This paper presents a detailed survey on new developments in control design techniques of LCNs.First,some preliminary ...The control design problem plays a fundamental role in the study of logical control networks(LCNs).This paper presents a detailed survey on new developments in control design techniques of LCNs.First,some preliminary results on the semi-tensor product method and LCNs are reviewed.Then,we move on to some new developments for control design techniques of LCNs,including the reachable set approach,the pinning control technique,the control Lyapunov function approach,the event-triggered control technique,and the sampled-data control technique.Finally,an illustrative example is given to demonstrate the effectiveness of these techniques.展开更多
Interstitial carbon and substitutional transition metal(TM)solutes are common impurities in tungsten and tungsten alloys.Yet,despite its important role in affecting mechanical and irradiation performances of tungsten,...Interstitial carbon and substitutional transition metal(TM)solutes are common impurities in tungsten and tungsten alloys.Yet,despite its important role in affecting mechanical and irradiation performances of tungsten,the interplay between these impurities remains largely unknown.In this work,we performed systematic first-principles simulations to study the interaction between carbon and TM solutes.By calculating related binding energies,we found that interplay between carbon and TM solutes is dominated by elastic interactions,with carbon generally showing attractions to TM solutes.Further,including vacancies in our calculation,we found that all solute-vacancy-carbon complexes are energetically stable with respect to associated point defects.Additional analysis shows that vacancy-carbon binding is generally weakened by TM solutes,while carbon also in turn reduces the binding energy between vacancy and TM solutes.Based on these binding energy results,we,respectively,evaluated the effect of solute and carbon on each other’s diffusion behaviors.We found that Cr and V slightly decrease the carbon diffusivity while other commonly seen TM solutes show little impacts on carbon diffusion,and we also expect carbon to slow down vacancy-mediated TM solute diffusion in tungsten.展开更多
基金Key Research and Development Program of Shandong Province,China (No. 2021ZLGX01)the National Natural Science Foundation of China (No. 52071190)the Shandong Provincial Natural Science Foundation,China (No. ZR2021YQ34)。
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFE0308102)the National Natural Science Foundation of China(Grant Nos.11735015 and 51771185)+1 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.17KJB140008)Jinling Institute of Technology,China(Grant Nos.jit-fhxm-201601 and jit-b-201616)
文摘The carbon diffusivity in tungsten is one fundamental and essential factor in the application of tungsten as plasmafacing materials for fusion reactors and substrates for diamond growth. However, data on this are quite scarce and largely scattered. We perform a series of first-principles calculations to predict the diffusion parameters of carbon in tungsten,and evaluate the effect of temperature on them by introducing lattice expansion and phonon vibration. The carbon atom prefers to occupy octahedral interstitial site rather than tetrahedral interstitial site, and the minimum energy path for its diffusion goes through a tetrahedral site. The temperature has little effect on the pre-exponential factor but a marked effect on the activation energy, which linearly increases with the temperature. Our predicted results are well consistent with the experimental data obtained at high temperature(>1800 K) but significantly larger than the experimental results at low temperature(<1800 K).
基金National Natural Science Foundation of China(Grant Nos.51701095 and 51771185)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20170798).
文摘The interactions of solute atoms with vacancies play a key role in diffusion and precipitation of alloying elements,ultimately influencing the mechanical properties of aluminum alloys.In this study,first-principles calculations are systematically performed to quantify the solute–vacancy interactions for the 3d–4p series and the 4d–5p series.The solute–vacancy interaction gradually transforms from repulsion to attraction from left to right.The solute–vacancy binding energy is sensitive to the supercell size for elements at the beginning.These behaviors of the solute–vacancy binding energy can be understood in terms of the combination and competition between the elastic and electronic interactions.Overall,the electronic binding energy follows a similar trend to the total binding energy and plays a major role in the solute–vacancy interactions.
基金Project supported by the National Natural Science Foundation of China(No.61873150)the Natural Science Fund for Distinguished Young Scholars of Shandong Province,China(No.JQ201613)the Young Experts of Taishan Scholar Project,China(No.201909076)。
文摘The control design problem plays a fundamental role in the study of logical control networks(LCNs).This paper presents a detailed survey on new developments in control design techniques of LCNs.First,some preliminary results on the semi-tensor product method and LCNs are reviewed.Then,we move on to some new developments for control design techniques of LCNs,including the reachable set approach,the pinning control technique,the control Lyapunov function approach,the event-triggered control technique,and the sampled-data control technique.Finally,an illustrative example is given to demonstrate the effectiveness of these techniques.
基金The authors would like to acknowledge the financial supports from the National Key R&D Program of China(Grant No.2019YFE03110200)the National Natural Science Foundation of China(Grant Nos.52071190,51771185)+1 种基金the project ZR2021YQ34 supported by Shandong Provincial Natural Science Foundationthe Key Research and Development Program of Shandong Province(Grant No.2021ZLGX01).
文摘Interstitial carbon and substitutional transition metal(TM)solutes are common impurities in tungsten and tungsten alloys.Yet,despite its important role in affecting mechanical and irradiation performances of tungsten,the interplay between these impurities remains largely unknown.In this work,we performed systematic first-principles simulations to study the interaction between carbon and TM solutes.By calculating related binding energies,we found that interplay between carbon and TM solutes is dominated by elastic interactions,with carbon generally showing attractions to TM solutes.Further,including vacancies in our calculation,we found that all solute-vacancy-carbon complexes are energetically stable with respect to associated point defects.Additional analysis shows that vacancy-carbon binding is generally weakened by TM solutes,while carbon also in turn reduces the binding energy between vacancy and TM solutes.Based on these binding energy results,we,respectively,evaluated the effect of solute and carbon on each other’s diffusion behaviors.We found that Cr and V slightly decrease the carbon diffusivity while other commonly seen TM solutes show little impacts on carbon diffusion,and we also expect carbon to slow down vacancy-mediated TM solute diffusion in tungsten.