The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields...The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas （free molecule regime）. Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.展开更多
In this paper,the power law of particle size distributions (PSDs) in conventional water treatment processes is developed. After measuring the particle size distributions of raw-water,settled water and filtered water,a...In this paper,the power law of particle size distributions (PSDs) in conventional water treatment processes is developed. After measuring the particle size distributions of raw-water,settled water and filtered water,a mathematical model between particle diameter and the amount of particles was studied. The value of collision frequency factor β in the PSDs model can be used to represent the collision behavior of particles ,and can be used as foundation exponent to choose suitable coagulation to accelerate particles aggregation. At the same time,the relationship between the value of parameter K and the total particles volume V was deduced. K is defined as particle volume exponent,which can represent the total volume of particles. The degression degree of K shows the removal efficiency of potable water treatment units.展开更多
针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统的峰均功率比高的缺点,提出一种新的相位因子优选对方法,降低OFDM系统的峰均比。相位因子优选对方法原理是,筛选出多个低峰均功率比的子序列,将这些子序列重组...针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统的峰均功率比高的缺点,提出一种新的相位因子优选对方法,降低OFDM系统的峰均比。相位因子优选对方法原理是,筛选出多个低峰均功率比的子序列,将这些子序列重组后传输来降低系统峰值平均功率比(peak to average power ratio,PA-PR)。把相位因子优选对方法、粒子群优化算法(particle swarm optimization,PSO)与相位因子优选对结合的方法与传统PSO方法对比验证。仿真结果表明,把PSO与相位因子优选对结合的方法应用在OFDM系统中,获得了优于传统PSO算法0.1～0.2dB的PAPR性能值,证明了新方法的有效性。展开更多
针对无线射频识别(Radio Frequency Identification,RFID)系统在识别标签的过程中出现标签碰撞识别效率不高的问题,在传统的自适应多叉树的基础上,提出了一种新型的自适应多叉树(NAMS)的防碰撞算法,该算法在计算碰撞因子选择叉数之前先...针对无线射频识别(Radio Frequency Identification,RFID)系统在识别标签的过程中出现标签碰撞识别效率不高的问题,在传统的自适应多叉树的基础上,提出了一种新型的自适应多叉树(NAMS)的防碰撞算法,该算法在计算碰撞因子选择叉数之前先估算碰撞标签数目N和统计碰撞位数m,直接识别满足N=2m的关系的叶子节点,节省了部分叶子节点的搜索时间;同时引入自动休眠计数机制,平均节省了一半的执行命令数,从而缩短了通信时间.最后对NAMS算法所需总时隙进行理论分析并将该算法用于实验,结果表明,NAMS算法较AMS算法在识别速度和系统吞吐率方面有较大提高.展开更多
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 50476010）.
文摘The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas （free molecule regime）. Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.
基金Sponsored by the National Basic Research Program of China(973)(Grant No.2004CB41850)the Natural Science Foundation of Heilongjiang Prov-ince(Grant No.E200609)
文摘In this paper,the power law of particle size distributions (PSDs) in conventional water treatment processes is developed. After measuring the particle size distributions of raw-water,settled water and filtered water,a mathematical model between particle diameter and the amount of particles was studied. The value of collision frequency factor β in the PSDs model can be used to represent the collision behavior of particles ,and can be used as foundation exponent to choose suitable coagulation to accelerate particles aggregation. At the same time,the relationship between the value of parameter K and the total particles volume V was deduced. K is defined as particle volume exponent,which can represent the total volume of particles. The degression degree of K shows the removal efficiency of potable water treatment units.
文摘针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统的峰均功率比高的缺点,提出一种新的相位因子优选对方法,降低OFDM系统的峰均比。相位因子优选对方法原理是,筛选出多个低峰均功率比的子序列,将这些子序列重组后传输来降低系统峰值平均功率比(peak to average power ratio,PA-PR)。把相位因子优选对方法、粒子群优化算法(particle swarm optimization,PSO)与相位因子优选对结合的方法与传统PSO方法对比验证。仿真结果表明,把PSO与相位因子优选对结合的方法应用在OFDM系统中,获得了优于传统PSO算法0.1～0.2dB的PAPR性能值,证明了新方法的有效性。
文摘针对无线射频识别(Radio Frequency Identification,RFID)系统在识别标签的过程中出现标签碰撞识别效率不高的问题,在传统的自适应多叉树的基础上,提出了一种新型的自适应多叉树(NAMS)的防碰撞算法,该算法在计算碰撞因子选择叉数之前先估算碰撞标签数目N和统计碰撞位数m,直接识别满足N=2m的关系的叶子节点,节省了部分叶子节点的搜索时间;同时引入自动休眠计数机制,平均节省了一半的执行命令数,从而缩短了通信时间.最后对NAMS算法所需总时隙进行理论分析并将该算法用于实验,结果表明,NAMS算法较AMS算法在识别速度和系统吞吐率方面有较大提高.
