This paper presents an improved rate control method for H.264. First, the scene changes are detected by the average absolute difference of the brightness histograms between the adjacent frames. Then, the bit allocatio...This paper presents an improved rate control method for H.264. First, the scene changes are detected by the average absolute difference of the brightness histograms between the adjacent frames. Then, the bit allocation and quantization parameters are adjusted, using a certain threshold. In addition, the calculation of the mean absolute difference （MAD） is modified in an alternative way, which makes the rate distortion optimization （RDO） more accurate. Extensive simulation results show that the proposed method, compared with G012, can improve the average peak signal-to-noise ratio （PSNR） and moderate the image quality.展开更多
The bit number allocation strategy of TM5 may cause the coding quality loss and buffer overflow at scene changes, therefore a new algorithm on MPEG2 target bit number allocation is proposed in this paper. Here the ...The bit number allocation strategy of TM5 may cause the coding quality loss and buffer overflow at scene changes, therefore a new algorithm on MPEG2 target bit number allocation is proposed in this paper. Here the influence of scene changes on coding quality is analyzed and an approach to improve the coding performance at scene changes is presented to avoid sharp quality loss of scene change frames. Simulation indicates that this algorithm provides a promising coding quality at scene changes.展开更多
[ Objective ] The paper was to explore the application of botanical pesticides on controlling turnip aphid （ Lipaphis erysimi Kaltenbach）. [ Method ] Through potting efficacy experiment of Chinese cabbage, the contr...[ Objective ] The paper was to explore the application of botanical pesticides on controlling turnip aphid （ Lipaphis erysimi Kaltenbach）. [ Method ] Through potting efficacy experiment of Chinese cabbage, the control effects of two preparations（20% EC and 10% EW）of methanol extract of Blumea megacephala Chang et Tseng against turnip aphid, as well as leaf-protection effect on Chinese cabbage were determined. [ Result] 20% EC of B. megacephala had the highest efficacy in 10-fold dilution, and its control effects against turnip aphid were 57.78%, 77.19% and 84.79% after pesticide spraying for 24, 48 and 72 h; 10% EW of B. megacephala had the highest efficacy in 5-fold dilution, and its control effects against turnip aphid were 74.44%, 84.79% and 89.14% after pesticide spra- ying for 24, 48 and 72 h. The leaf-protection rates of 20% EC orB. megacephala in 10-fold dilution were 89.31% and 94.80% after pesticide spraying for 3 and 5 d; the leaf-protection rates of 10% EW of B. megacephala in 5-fold dilution were 93.50% and 97.83% after pesticide spraying for 3 and 5 d. [ Condusion] The methanol extract of B. megacephala had good control effect against turnip aphid and good protection rate on crops.展开更多
变量施肥是精准农业的重要组成部分,非线性、大惯性和参数时变性是影响水肥一体化控制系统精度和稳态性能的关键因素。PID控制算法因其简单方便而被人们广泛应用于工农业领域中,但往往很难达到理想的控制效果。灰狼优化算法(Gray Wolf O...变量施肥是精准农业的重要组成部分,非线性、大惯性和参数时变性是影响水肥一体化控制系统精度和稳态性能的关键因素。PID控制算法因其简单方便而被人们广泛应用于工农业领域中,但往往很难达到理想的控制效果。灰狼优化算法(Gray Wolf Optimization Algorithm, GWO)是一种参数设置少且收敛性能好的群体智能优化算法,但在迭代过程中容易陷入局部最优解。为此,通过在标准GWO算法中引入遗传交叉和变异算子,结合佳点集方法,提出一种改进的新型灰狼智能优化算法(Genetic–Grey Wolf Optimization algorithm, GGWO),并将改进的遗传-灰狼优化算法应用于水肥一体化控制系统的PID控制中。以液肥控制系统为研究对象,建立相应的负反馈控制系统数学模型,分别采用常规PID控制、基于GWO的PID控制以及基于GGWO的PID等3种不同控制方法并用MatLab对其进行仿真,并对比分析了各控制方法下的系统性能指标。仿真结果表明:基于GGWO的PID控制在系统的上升时间、调节时间和适应值等性能指标上都优于其它两种控制方法,在系统的精度、均匀性、鲁棒性和稳态性能上实现了更好的控制效果,不仅满足了精准农业的作业要求,而且为后续研究打下了基础。展开更多
Energy access,climate change and public health issues are some major drivers for the need for renewable sources.However,most renewable sources,excluding large hydro,have zero or negligible rotational inertia,which is ...Energy access,climate change and public health issues are some major drivers for the need for renewable sources.However,most renewable sources,excluding large hydro,have zero or negligible rotational inertia,which is critical to stabilizing the power system after contingency.Therefore,this paper proposes a droop-based inertia emulator to reduce the rate of change of frequency and frequency deviations.The robustness of the controller is analysed by applying various uncertainties and disturbances of power system components that were carried out using DIgSILENT PowerFactory simulations.The obtained results are compared with existing literature and the desired performance shows an improvement in the rate of change of frequency of 34.78%for an IEEE 6-bus system,24.32%for a 12-bus system and 18%for a 39-bus system.展开更多
基金Supported by the National Natural Science Foundation of China (60372057)
文摘This paper presents an improved rate control method for H.264. First, the scene changes are detected by the average absolute difference of the brightness histograms between the adjacent frames. Then, the bit allocation and quantization parameters are adjusted, using a certain threshold. In addition, the calculation of the mean absolute difference （MAD） is modified in an alternative way, which makes the rate distortion optimization （RDO） more accurate. Extensive simulation results show that the proposed method, compared with G012, can improve the average peak signal-to-noise ratio （PSNR） and moderate the image quality.
文摘The bit number allocation strategy of TM5 may cause the coding quality loss and buffer overflow at scene changes, therefore a new algorithm on MPEG2 target bit number allocation is proposed in this paper. Here the influence of scene changes on coding quality is analyzed and an approach to improve the coding performance at scene changes is presented to avoid sharp quality loss of scene change frames. Simulation indicates that this algorithm provides a promising coding quality at scene changes.
文摘[ Objective ] The paper was to explore the application of botanical pesticides on controlling turnip aphid （ Lipaphis erysimi Kaltenbach）. [ Method ] Through potting efficacy experiment of Chinese cabbage, the control effects of two preparations（20% EC and 10% EW）of methanol extract of Blumea megacephala Chang et Tseng against turnip aphid, as well as leaf-protection effect on Chinese cabbage were determined. [ Result] 20% EC of B. megacephala had the highest efficacy in 10-fold dilution, and its control effects against turnip aphid were 57.78%, 77.19% and 84.79% after pesticide spraying for 24, 48 and 72 h; 10% EW of B. megacephala had the highest efficacy in 5-fold dilution, and its control effects against turnip aphid were 74.44%, 84.79% and 89.14% after pesticide spra- ying for 24, 48 and 72 h. The leaf-protection rates of 20% EC orB. megacephala in 10-fold dilution were 89.31% and 94.80% after pesticide spraying for 3 and 5 d; the leaf-protection rates of 10% EW of B. megacephala in 5-fold dilution were 93.50% and 97.83% after pesticide spraying for 3 and 5 d. [ Condusion] The methanol extract of B. megacephala had good control effect against turnip aphid and good protection rate on crops.
文摘变量施肥是精准农业的重要组成部分,非线性、大惯性和参数时变性是影响水肥一体化控制系统精度和稳态性能的关键因素。PID控制算法因其简单方便而被人们广泛应用于工农业领域中,但往往很难达到理想的控制效果。灰狼优化算法(Gray Wolf Optimization Algorithm, GWO)是一种参数设置少且收敛性能好的群体智能优化算法,但在迭代过程中容易陷入局部最优解。为此,通过在标准GWO算法中引入遗传交叉和变异算子,结合佳点集方法,提出一种改进的新型灰狼智能优化算法(Genetic–Grey Wolf Optimization algorithm, GGWO),并将改进的遗传-灰狼优化算法应用于水肥一体化控制系统的PID控制中。以液肥控制系统为研究对象,建立相应的负反馈控制系统数学模型,分别采用常规PID控制、基于GWO的PID控制以及基于GGWO的PID等3种不同控制方法并用MatLab对其进行仿真,并对比分析了各控制方法下的系统性能指标。仿真结果表明:基于GGWO的PID控制在系统的上升时间、调节时间和适应值等性能指标上都优于其它两种控制方法,在系统的精度、均匀性、鲁棒性和稳态性能上实现了更好的控制效果,不仅满足了精准农业的作业要求,而且为后续研究打下了基础。
文摘Energy access,climate change and public health issues are some major drivers for the need for renewable sources.However,most renewable sources,excluding large hydro,have zero or negligible rotational inertia,which is critical to stabilizing the power system after contingency.Therefore,this paper proposes a droop-based inertia emulator to reduce the rate of change of frequency and frequency deviations.The robustness of the controller is analysed by applying various uncertainties and disturbances of power system components that were carried out using DIgSILENT PowerFactory simulations.The obtained results are compared with existing literature and the desired performance shows an improvement in the rate of change of frequency of 34.78%for an IEEE 6-bus system,24.32%for a 12-bus system and 18%for a 39-bus system.
