The intrinsic thermodynamical factors that dominate the stability of nanocrystallines are investigated through the microcosmic process of grain growth.The results suggest that nanocrystallines grows at a certain tempe...The intrinsic thermodynamical factors that dominate the stability of nanocrystallines are investigated through the microcosmic process of grain growth.The results suggest that nanocrystallines grows at a certain temperature and the critical temperature is determined by the vacancy formation energy and diffusion activation energy of the nanocrystallines.Based on the hypothesis,a simple model is proposed to predict the size-dependent critical temperature of grain growth.Within this model,we investigate the thermal stability of nanocrystallines V and Au,compared with the results available.It is shown that the critical temperature decreases with decreasing size,showing an evident size effect.The research reveals that the thermal stability is dependent on the energetic state of the nanocrystallines and the mobility of the inner atoms.展开更多
For nanostructure SnO2,it is very difficult for its electric properties to accurately control due to the presence of abundant surface states.The introduction of Sm can improve the traps in surface space charge region ...For nanostructure SnO2,it is very difficult for its electric properties to accurately control due to the presence of abundant surface states.The introduction of Sm can improve the traps in surface space charge region of SnO2 nanowires,resulting in a controllable storage charge effect.For the single nanowire-based two-terminal device,two surface state-related back-to-back diodes are formed.At a relatively large voltage,electrons can be injected into the traps in surface space charge region from negative electrode,resulting in a decrease of surface barrier connected with negative electrode,and contrarily electrons can be extracted from the traps in surface space charge region into positive electrode,resulting in an increase of surface barrier connected with positive electrode.The reversible injection and extraction induce a nonvolatile resistive switching memory effect.展开更多
In order to reduce the disturbance on an authorizing user and lower the competition between cognitive users, assure the normal communication of a cognitive radio system, reliability theory is applied to describe if a ...In order to reduce the disturbance on an authorizing user and lower the competition between cognitive users, assure the normal communication of a cognitive radio system, reliability theory is applied to describe if a channel can be used by a cognitive user or not and the probability that the channel is continually used for a period. Three aspects including space, time domain and frequency domain are united for the research on the distribution of frequency spectrum. The simulation result shows that, in the space domain, time domain, frequency domain algorithm, the transmitted data volume and the total throughput of the system are superior to those in greedy algorithm and time domain—frequency domain algorithm, the novel algorithm is helpful to reduce the disturbance caused by a cognitive user to an authorizing user and lower the competition between cognitive users, this simulation result shows that the proposed algorithm is effective.展开更多
We theoretically investigate chaotic dynamics in an optomechanical system composed of a whispering-gallery-mode(WGM)microresonator and a sensor.We find that tuning the optical phase using a phase shifter and modifying...We theoretically investigate chaotic dynamics in an optomechanical system composed of a whispering-gallery-mode(WGM)microresonator and a sensor.We find that tuning the optical phase using a phase shifter and modifying the coupling strength via a unidirectional waveguide(IWG)can induce chaotic motion.The underlying reason for this phenomenon is that adjusting the phase and coupling strength via the phase shifter and IWG bring the system close to an exceptional point(EP),where field localization dynamically enhances the optomechanical nonlinearity,leading to the generation of chaotic motion.In addition,due to the sensitivity of chaos to phase in the vicinity of the EP,we propose a theoretical scheme to measure the optical phase perturbations using chaos.Our work may offer an alternative approach to chaos generation with current experimental technology and provide theoretical guidance for optical signal processing and chaotic secure communication.展开更多
Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demon...Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demonstrates that the melting temperature is related to the size and composition of alloy nanoparticles. The melting temperature of CuNi, PbBi and Snln binary alloy nanocrystals is found to be consistent with the experiments and molecular dynamics simulations. The research reveals that alloy nanocrystals have similar melting nature as pure metal.展开更多
基金by the Scientific Research Fund of Hunan Provincial Science and Technology Department(2009FJ3153).
文摘The intrinsic thermodynamical factors that dominate the stability of nanocrystallines are investigated through the microcosmic process of grain growth.The results suggest that nanocrystallines grows at a certain temperature and the critical temperature is determined by the vacancy formation energy and diffusion activation energy of the nanocrystallines.Based on the hypothesis,a simple model is proposed to predict the size-dependent critical temperature of grain growth.Within this model,we investigate the thermal stability of nanocrystallines V and Au,compared with the results available.It is shown that the critical temperature decreases with decreasing size,showing an evident size effect.The research reveals that the thermal stability is dependent on the energetic state of the nanocrystallines and the mobility of the inner atoms.
基金financially supported by the National Natural Science Foundation of China(No.51571107)the Key Project of Hunan Provincial Department Education(No.17A222)
文摘For nanostructure SnO2,it is very difficult for its electric properties to accurately control due to the presence of abundant surface states.The introduction of Sm can improve the traps in surface space charge region of SnO2 nanowires,resulting in a controllable storage charge effect.For the single nanowire-based two-terminal device,two surface state-related back-to-back diodes are formed.At a relatively large voltage,electrons can be injected into the traps in surface space charge region from negative electrode,resulting in a decrease of surface barrier connected with negative electrode,and contrarily electrons can be extracted from the traps in surface space charge region into positive electrode,resulting in an increase of surface barrier connected with positive electrode.The reversible injection and extraction induce a nonvolatile resistive switching memory effect.
基金supported by Natural Science Foundation of Heilongjiang Province of China(No.F2015017)
文摘In order to reduce the disturbance on an authorizing user and lower the competition between cognitive users, assure the normal communication of a cognitive radio system, reliability theory is applied to describe if a channel can be used by a cognitive user or not and the probability that the channel is continually used for a period. Three aspects including space, time domain and frequency domain are united for the research on the distribution of frequency spectrum. The simulation result shows that, in the space domain, time domain, frequency domain algorithm, the transmitted data volume and the total throughput of the system are superior to those in greedy algorithm and time domain—frequency domain algorithm, the novel algorithm is helpful to reduce the disturbance caused by a cognitive user to an authorizing user and lower the competition between cognitive users, this simulation result shows that the proposed algorithm is effective.
基金supported by the National Science Fund for Distinguished Young Scholars of China(Grant No.12425502)the National Natural Science Foundation of China(Grant Nos.12304395,and 12004202)+5 种基金the National Key Research and Development Program of China(Grant No.2021YFA1400700)the Fundamental Research Funds for the Central Universities(Grant No.2024BRA001)the Jianghan University Natural Science General Project(Grant No.2021yb028)the Luoyang Institute of Science and Technology Natural Science General Project(Grant No.21010777)the Chunhui Project Foundation of the Education Department of China(Grant No.HZKY20220337)the Natural Science Foundation of Hubei Province(Grant No.2023AFB891)。
文摘We theoretically investigate chaotic dynamics in an optomechanical system composed of a whispering-gallery-mode(WGM)microresonator and a sensor.We find that tuning the optical phase using a phase shifter and modifying the coupling strength via a unidirectional waveguide(IWG)can induce chaotic motion.The underlying reason for this phenomenon is that adjusting the phase and coupling strength via the phase shifter and IWG bring the system close to an exceptional point(EP),where field localization dynamically enhances the optomechanical nonlinearity,leading to the generation of chaotic motion.In addition,due to the sensitivity of chaos to phase in the vicinity of the EP,we propose a theoretical scheme to measure the optical phase perturbations using chaos.Our work may offer an alternative approach to chaos generation with current experimental technology and provide theoretical guidance for optical signal processing and chaotic secure communication.
基金supported by the Scientific Research Fund of Hunan Provincial Science & Technology Department (Grant No. 2009FJ3153)
文摘Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demonstrates that the melting temperature is related to the size and composition of alloy nanoparticles. The melting temperature of CuNi, PbBi and Snln binary alloy nanocrystals is found to be consistent with the experiments and molecular dynamics simulations. The research reveals that alloy nanocrystals have similar melting nature as pure metal.
