复杂背景下实时运动目标的提取

提出了一种结合帧间减法与背景自适应更新的算法,结合高速图像处理平台,以满足实时运动目标的提取。着眼于算法的高速性并提出一种足够快的方法用于弹道测量系统。用高斯分布建立每个像素的灰度模型,这个分布用来区分前景和背景像素以便用来更新背景模型。实验表明该系统可以满足靶场弹道测量任务实时性的要求,传统大量占用系统资源的算法在该系统中得到改善,大大提高了系统的实时性。     

Up-conversion detection of mid-infrared light carrying orbital angular momentum

Frequency up-conversion is an effective method of mid-infrared (MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum (OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.     

液相色谱-串联质谱法快速筛查测定浓缩果蔬汁中的156种农药残留

建立了浓缩果蔬汁中156种农药多残留的液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)测定方法。样品用1%醋酸乙腈溶液萃取,经Waters Sep-Pak Vac固相萃取柱净化,乙腈-甲苯(体积比为3∶1)洗脱,旋转蒸发浓缩,用乙腈-水（体积比为3∶2）溶解,以Agilent ZORBAX SB-C18色谱柱分离,以电喷雾电离串联质谱在正离子多反应监测(MRM)模式下进行测定。对156种农药在5种浓缩果蔬汁(橙汁、苹果汁、葡萄汁、白菜汁、胡萝卜汁)中两个添加水平下的回收率进行了测定,回收率范围为57.2%～122.7%,相对标准偏差范围为0.9%～19.8%。方法的检出限(S/N=3)和定量限(S/N=10)范围分别为0.10～56.77 μg/kg和0.33～189.23 μg/kg。该方法样品前处理简单、快速、分析时间短,灵敏度、准确度和精密度均符合农药多残留检测技术的要求,适用于苹果汁、橙汁、葡萄汁、白菜汁、胡萝卜汁等浓缩果蔬汁中156种农药多残留的快速筛查测定。     

(Ni0.81Fe0.19)1－xCrx作为种子层对NiFe/PtMn双层膜交换偏置的影响

将NiFe/PtMn双层膜生长在(Ni_0.81Fe_0.19)_1-xCr_x种子层材料上，通过改变种子层中Cr的原子含量，系统的研究了NiFe/PtMn双层膜中PtMn晶粒尺寸和织构对交换偏置的影响.对退火270℃，5h后的NiFe/PtMn双层膜磁性的研究表明,PtMn织构强弱对交换偏置场的影响不明显，而PtMn的晶粒尺寸是影响交换偏置场的主要因素，PtMn颗粒的相干长度在11.3nm左右时得到了较大的交换偏置场. 关键词： NiFe/PtMn双层膜 交换偏置场     

不确定自催化反应扩散时空混沌系统的延时同步

设计了一种延迟同步控制器实现了时空混沌系统之间的同步控制.基于Lyapunov稳定性定理,确定了延迟同步控制器的结构以及系统状态变量之间的误差方程.以自催化反应扩散时空混沌系统为例,仿真模拟验证了该控制器的有效性.进一步设计了参量辨识器,对不确定自催化反应扩散时空混沌系统中的参量进行了有效辨识.通过研究有界噪声影响下系统的同步效果,表明该同步方法具有较好的抗干扰能力. 关键词： 时空混沌 延时同步 参量辨识 有界噪声     

星载激光多普勒测风雷达鉴频系统仿真(I):基于Fizeau干涉仪的Mie通道大气风速反演研究

研究了星载激光多普勒测风雷达系统结构,构建了基于Fizeau干涉仪的鉴频仿真系统,仿真研究了Mie通道风速反演算法,并利用无线电探空数据集仿真结果统计分析了Mie通道大气水平视线(HLOS)风速反演误差.仿真和统计结果表明,基于Fizeau干涉仪的Mie通道可反演低对流层大气风速;低对流层HLOS风速误差和标准差分别小于1 m·s-1和2 m·s-1;气溶胶和云的分布影响星载激光多普勒雷达测风误差,可使风速最大偏差增大一倍.     

Structural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressure

The structural stability and electrical properties of A1B2-type MnB2 were studied based on high pressure angle- dispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell （DAC） and first-principles calcu- lations under high pressure. The x-ray diffraction results show that the structure of A1B2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9~3.7 GPa with a fixed pressure derivative of 4, which indicates that A1B2-type MnB2 is a hard and incompressible material. The electrical resistance un- dergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.     

灵巧型离轴三反光学系统设计

基于同轴三反射光学系统基本原理,将孔径光阑和视场适当偏心,设计了一个灵巧型多光谱离轴三反光学系统,系统焦距1 200 mm,并对设计结果进行了像质评价。实验结果表明:系统在可见波段（0.486 m ~0.656 m）80 lp/mm空间频率下MTF0.5,中波波段（3 m ~5 m）15 lp/mm空间频率下MTF0.35,全波段范围内最大RMS为2.096 m。系统中面型采用二次非球面,且整个系统仅有孔径光阑偏心,3个反射镜位置均无偏心和倾斜,降低了加工成本及装调难度。     

In-situ high pressure X-ray diffraction studies of orthoferrite SmFeO_3

The high-pressure behaviors of SmFeO3 are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO3 remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be βa = 0.60 × 10-3 GPa-1,βb = 0.79 × 10-3 GPa-1, βc = 1.28 × 10-3 GPa- 1, and the bulk modulus （B0） is determined to be 293（3） GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. Furthermore, the larger compressibility of the FeO6 octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures.     

标准状态下氮气在0.145～2.058μm的色散特性

为了研究氮气在宽光谱范围内的色散特性,基于气体色散理论,在标准条件下(温度为293.15K,气压为101325Pa),利用二阶Sellmeier公式和最小二乘法拟合得到氮气在0.145～2.058μm波长范围内的色散公式。该公式在全波段范围内的不确定度约为2.1×10-7,与原始测量数据的准确度一致。与现有色散公式相比,该公式的适用波长范围更宽,可提供氮气在0.27～0.47μm波段更多的折射率信息,具有较广泛的适用性。通过实验测量氮气在633nm处的折射率验证了该公式的有效性。