Strange quark dynamics on hot dense matter under the extreme condition

Production and properties of φ-meson under the extreme hot dense matter which is formed in Au ＋ Au collisions at RHIC energy have been briefly reviewed.The issues are focused on transverse momentum （p T ） spectra of φ,elliptic flow of φ,nuclear modification factor of φ,the ratio of Ω（p T ）/φ（p T ） versus p T,the ratio of Ω（p T /3）/φ（p T /2） versus p T /n q,spin alignment of φ and the enhancement of φ etc.These observables give the significant information of the strange quark dynamics in hot dense matter under the extreme condition.     

Dipole bands in nucleus ~(139)Pm

High-spin states in nucleus 139Pm have been studied using the reaction 116Cd(27Al,4n)139Pm.Two dipole cascades have been found.Spin and parity assignments were based on the Directional Correlation of Oriented Nuclei(DCO) ratios and systematic behavior in neighboring odd-proton nuclei.The level structures of 139Pm are compared with those of the N =78 isotone 141Eu in which two dipole bands have been confirmed as magnetic rotational bands.The close similarity between them suggests that the dipole bands in 139...     

基于无记忆状态观测器的多时滞不确定非线性系统的自适应控制

针对一类多时滞不确定非线性系统,研究了基于无记忆状态观测器的自适应控制问题.时滞状态扰动的上界未知,在控制中通过自适应律估计未知参数,并利用估计值设计了不依赖于时滞的无记忆状态观测器和控制器,基于Lyapunov-Krasovskii函数证明了观测误差渐近收敛到零.最后仿真结果说明了该方法的有效性.     

利用光栅光谱仪研究乙醇汽油溶液的吸收特性

利用WGD-8A型多功能光栅光谱仪测量了不同汽油体积含量的乙醇汽油溶液对波长为300.0～430.0 nm光的吸收光谱,分析了乙醇汽油吸光度和汽油浓度的关系,在稀溶液吸光度的朗伯-比尔定律基础上,进一步研究了2种高浓度混合溶液吸光度的计算方法,并得出了入射光波长为377.0,382.0,391.5,410.9 nm时乙醇汽油的吸光度与汽油体积浓度的关系式.     

采用较长脉宽双色场获得孤立阿秒脉冲

通过数值求解一维含时薛定谔方程,本文研究了具有较长脉宽双色激光脉冲与氢原子模型相互作用产生的谐波辐射谱.研究发现,当采用12个光学周期的特定组合脉冲时,孤立阿秒脉冲可以实现.这里特定组合脉冲由两束类似频率脉冲(ω,ω+δω)构成,附加脉冲的作用恰是调整基频光电场的形状.不同于入射基频光,整形后的基频光在时间始末端电场振幅被抑制,只有中间部分电场对谐波谱有贡献,它的作用等同于单一6飞秒超短脉冲的效果.从而扩展获得孤立阿秒脉冲所需脉宽从6飞秒到12飞秒.     

Design study of a L-band photocathode RF injector

In the proposal of the Beijing Advanced Light Source, a compact combination of XERL and XFEL using a common SC linac is being considered. In the meantime, an ERL-FEL test facility is being proposed and will be used for THz radiation. In this test facility, a L-band photocathode RF injector is needed. In this paper, we give the physical design of the L-band photocathode RF injector for the test facility.     

Physical design of scanning gantry for proton therapy facility

A proton therapy facility based on a linac injector and a slow cycling synchrotron is proposed.To achieve effective treatment of cancer,a scanning gantry is required.The flexible transmission of beam and high beam position accuracy are the most basic requirements for a gantry.The designed gantry optics and scanning system are presented.Great efforts are put into studying the sensitivity of the beam position in the isocenter to the element misalignments.It shows that quadrupole shift makes the largest contribution and special attention should be paid to it.     

Study of separated function radio frequency quadrupoles accelerator

SFRFQ (Separated Function Radio Frequency Quadrupoles) accelerator is a new post accelerator of RFQ (Radio Frequency Quadrupoles) type, which has been developed since the beginning of the 1990s at Peking University. In order to demonstrate the possibility of the SFRFQ, a prototype cavity has been designed.A special dynamics design method has been proposed to avoid the sparking problem and decrease the energy spread at the exit of SFRFQ. It consists of two aspects: the asymmetry structure design for transverse focusing and the inner buncher design for longitudinal bunching. This allows the improvement of the beam properties without increasing the cavity length. The simulation results show that the energy spread can be substantially reduced by using the inner buncher in the SFRFQ structure.     

外来物种紫茎泽兰光谱特征

紫茎泽兰是一种有毒的外来物种,对我国经济和环境产生了深远的影响。紫茎泽兰具有分布广、扩散快的特征,使得传统监测手段显得捉襟见肘。文章在分析了紫茎泽兰光谱特征的基础上,尝试建立紫茎泽兰遥感识别模型,旨在挖掘有效的紫茎泽兰空间分布动态监测方法。研究表明:紫茎泽兰光谱曲线在可见光范围内有2个反射峰和1个吸收谷,对应的波长分别为560,730和674 nm。紫茎泽兰在674 nm的吸收深度为0.504 3～1.910 3,吸收宽度为13.778 9～17.2518 nm,中心吸收波段的左右面积呈左偏型,且左边面积与右边面积的比值为1.771 9～2.444 1。紫茎泽兰白色的花使光谱反射率在可见光范围内有一明显的抬升,并导致一阶微分光谱在420 nm产生一个波峰。与其他典型地物的光谱特征对比可知,紫茎泽兰在674 nm的吸收宽度和左右面积比值以及420 nm的一阶导数值是花期紫茎泽兰独有的光谱特征,可作为花期遥感识别与提取紫茎泽兰的重要参数。     

高阶辛算法的稳定性与数值色散性分析

利用Maxwell方程的哈密尔顿函数,导出对应的欧拉-哈密尔顿方程.利用辛积分技术与高阶交错差分技术,建立求解三维时域Maxwell方程的高阶辛算法;结合电磁场中的物理概念,借助矩阵分析和张量分析理论,获得高阶时域方法及高阶辛算法的稳定性和数值色散性的统一处理新方法.用数值结果证实方法的正确性,与FDTD算法和其它时域高阶方法相比,高阶辛算法具有较大的计算优势,为电磁计算提供了新的途径.