A mathematical model of quantum noise having much effect on the low light imaging system is set up. To simulate the quantum noise, the random numbers obeying noise distribution must be formed and are weighted on the...A mathematical model of quantum noise having much effect on the low light imaging system is set up. To simulate the quantum noise, the random numbers obeying noise distribution must be formed and are weighted on the basis of the model created. Three uniform random sequences are built by the linear congruential method, of which two are used to form integer number and decimal fraction parts of the new random sequence respectively and the third to shuffle the new sequence. And then a Gauss sequence is formed out of uniform distribution by a function transforming method. It actualizes the simulation in real time of quantum noise in the low light imaging system, where video flow is extracted in real time, the noise summed up and played back side by side with the original video signs by a simulation software.展开更多
In this study, a linear model predictive control(MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the fram...In this study, a linear model predictive control(MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the framework of MPC to relax the assumption of integrated white noise model in existing approaches. The introduced filters are globally optimal for linear systems with unmeasured disturbances that have unknown statistics. This enables the proposed MPC to better handle disturbances without access to disturbance statistics. As a result, the effort required for disturbance modeling can be alleviated. The proposed MPC can achieve offset-free control in the presence of asymptotically constant unmeasured disturbances. Simulation results demonstrate that the proposed approach can provide an improved disturbance ?rejection performance over conventional approaches when applied to the control of systems with unmeasured disturbances that have arbitrary statistics.展开更多
To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation(forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is propos...To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation(forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is proposed recently (Shang et al., 2001). In this paper, numerical simulation has been conducted for acoustic propagation through the Polar Front to verify the new criterion. Numerical results on the f (frequency) -m (mode number) plan demonstrate that the new criterion works very well for this extremely non-gradual ocean structure.展开更多
For the first time detailed measurements of the DOS （density of states） for Ti3AIC2 and Ti3SiC2 are presented at temperatures between T = 10 and 100 K. For Ti3AIC2 a DFT （density functional theory） simulation of l...For the first time detailed measurements of the DOS （density of states） for Ti3AIC2 and Ti3SiC2 are presented at temperatures between T = 10 and 100 K. For Ti3AIC2 a DFT （density functional theory） simulation of lattice dynamics is compared to experimental data demonstrating a noticeable difference between the spectra especially below 40 meV. In the case of Ti3SiC2 the DFT model is augmented with MD （molecular dynamics） simulations resulting in the measured and simulated spectra resembling one another more closely but still having significant differences below 40 meV. Within the experimental spectra, there are features up to and including 20 meV which are unaccounted for by the simulation. Tracing individual atoms generated by the computer models suggests anharmonic motion of Si within the Ti3SiC2. The results presented could explain differences between calculated elastic moduli using DFT harmonic lattice dynamics simulations and results from recent experiments.展开更多
Underwater wireless sensor networks(UWSNs) have attracted wide attention in recent years.The capacity research on it is still in the initial stage,lacking adequate performance evaluation for network construction.This ...Underwater wireless sensor networks(UWSNs) have attracted wide attention in recent years.The capacity research on it is still in the initial stage,lacking adequate performance evaluation for network construction.This paper will focus on this subject by theoretical analysis and simulation,aiming to provide some insights for the actual UWSNs construction.According to the structure features of cluster-based UWSNs and the propagation characteristics of underwater acoustic signal,with the combination of signal to interference plus noise ratio,we define some capacity performance metrics,such as outage probability and transmission capacity.Based on the theory of stochastic geometry,a network capacity analytical model used in the cluster-based UWSNs is presented.The simulation results verify the validity of the theoretical analysis,and the cause of error between theoretical and simulation results has also been clearly explained.展开更多
文摘A mathematical model of quantum noise having much effect on the low light imaging system is set up. To simulate the quantum noise, the random numbers obeying noise distribution must be formed and are weighted on the basis of the model created. Three uniform random sequences are built by the linear congruential method, of which two are used to form integer number and decimal fraction parts of the new random sequence respectively and the third to shuffle the new sequence. And then a Gauss sequence is formed out of uniform distribution by a function transforming method. It actualizes the simulation in real time of quantum noise in the low light imaging system, where video flow is extracted in real time, the noise summed up and played back side by side with the original video signs by a simulation software.
基金Supported by the Startup Foundation of Hangzhou Dianzi University(ZX150204302002/009)the Open Project Program of the State Key Laboratory of Industrial Control Technology(Zhejiang University)National Natural Science Foundation of China(No.61374142,61273145,and 61273146)
文摘In this study, a linear model predictive control(MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the framework of MPC to relax the assumption of integrated white noise model in existing approaches. The introduced filters are globally optimal for linear systems with unmeasured disturbances that have unknown statistics. This enables the proposed MPC to better handle disturbances without access to disturbance statistics. As a result, the effort required for disturbance modeling can be alleviated. The proposed MPC can achieve offset-free control in the presence of asymptotically constant unmeasured disturbances. Simulation results demonstrate that the proposed approach can provide an improved disturbance ?rejection performance over conventional approaches when applied to the control of systems with unmeasured disturbances that have arbitrary statistics.
文摘To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation(forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is proposed recently (Shang et al., 2001). In this paper, numerical simulation has been conducted for acoustic propagation through the Polar Front to verify the new criterion. Numerical results on the f (frequency) -m (mode number) plan demonstrate that the new criterion works very well for this extremely non-gradual ocean structure.
文摘For the first time detailed measurements of the DOS （density of states） for Ti3AIC2 and Ti3SiC2 are presented at temperatures between T = 10 and 100 K. For Ti3AIC2 a DFT （density functional theory） simulation of lattice dynamics is compared to experimental data demonstrating a noticeable difference between the spectra especially below 40 meV. In the case of Ti3SiC2 the DFT model is augmented with MD （molecular dynamics） simulations resulting in the measured and simulated spectra resembling one another more closely but still having significant differences below 40 meV. Within the experimental spectra, there are features up to and including 20 meV which are unaccounted for by the simulation. Tracing individual atoms generated by the computer models suggests anharmonic motion of Si within the Ti3SiC2. The results presented could explain differences between calculated elastic moduli using DFT harmonic lattice dynamics simulations and results from recent experiments.
基金supported by National Natural Science Foundation of China(No.61101164)
文摘Underwater wireless sensor networks(UWSNs) have attracted wide attention in recent years.The capacity research on it is still in the initial stage,lacking adequate performance evaluation for network construction.This paper will focus on this subject by theoretical analysis and simulation,aiming to provide some insights for the actual UWSNs construction.According to the structure features of cluster-based UWSNs and the propagation characteristics of underwater acoustic signal,with the combination of signal to interference plus noise ratio,we define some capacity performance metrics,such as outage probability and transmission capacity.Based on the theory of stochastic geometry,a network capacity analytical model used in the cluster-based UWSNs is presented.The simulation results verify the validity of the theoretical analysis,and the cause of error between theoretical and simulation results has also been clearly explained.
