Theory and experiment of spatially and temporally partially coherent speckle shearing interferometry

The theory and experiment of spatially and temporally partially coherent speckle shearing interferometry is reported in this rapid communication for the first time. The general requirements for the surface roughness and coherence area of a diffuse object surface in spatially and temporally partially coherent speckle shearing interferometry are discussed. An experimental verification is presented and the results of theory and experiment are in good agreement.     

形如1/3(2~p+1)的孤立数

设p是奇素数.X_p=1/3(2~p+1),证明了:X_p都是孤立数.     

Rime- and glaze-ice accretion due to freezing rain falling vertically on a horizontal thermally insulated overhead line conductor

A theory of atmospheric icing due to freezing rain on an overhead line conductor (OHLC) is developed. The rain falls vertically on a horizontal OHLC that is thermally insulated. It is assumed that the collection efficiency of the accretion surface is unity and that this surface is in thermodynamic equilibrium with the environment.

For air temperature T_A 0°C and raindrop temperature T_D 0°C, the freezing rain accretes as rime ice, provided that the temperature of the ice surface T_l < 0°C. The evolution equation governing the mass transfer at the accretion surface is solved analytically, yielding the shape of the rime-ice surface. Equations governing the thermal state of the rime-ice deposit are also given. These determine the onset of wet growth or glaze accretion at the upper stagnation line during suitable environmental conditions.

For environmental conditions producing an ice surface at temperature T_l = 0°gC, the freezing accretes as glaze. Equations governing the heat and mass transfer at the surface determine the shape of the glaze surface and the downward viscous motion of the unfrozen water. For T_D < 0°C, glaze evolution equations are developed for T_A 0°C and T_A 0°C. Analytical solutions of these equations are obtained. In particular, when T_D < −T_A < 0°C, the evolution equation predicts a novel limiting growth that is triangular in shape. Further study of the mass and heat transfer conditions, in the neighborhood of this final stage of glaze accretion, shows that it is maintained in thermodynamic equilibrium with its warm air environment.     

一种机载超宽带相控阵雷达T/R组件设计

针对机载有源相控阵雷达小型化、多功能、高功率的要求,研制了一款应用于C、X、Ku波段的双通道超宽带T/R砖块组件,外观尺寸为30.0 mm×70.0 mm×8.5 mm.组件在工作频带内可以实现6位移相、6位衰减,工作带宽达到12 GHz,发射输出功率≥ 37 dBm,接收增益达到22 dB.通过对电路中无源结构进行仿真,并利用得到的仿真结果和射频芯片实现链路仿真,解决了超宽带T/R组件端口驻波较差和接收增益平坦度差且难以预估的难题.最终制造的T/R组件具有超宽带、低噪声、高功率以及良好的幅相性能.     

基于ERPMT改进启发式方法的WSN寿命最大化算法

针对传感器节点的电池容量限制导致无线传感网络寿命低的问题,基于容量最大化(CMAX)、线上最大化寿命(OML)两种启发式方法以及高效路由能量管理技术(ERPMT),提出了基于ERPMT改进启发式方法的无线传感网络寿命最大化算法。首先,通过启发式方法初始化每个传感器节点,将节点能量划分为传感器节点起源数据和其它节点数据延迟;然后利用加入的一种优先度量延迟一跳节点的能量消耗;最后,根据路径平均能量为每个路由分配一个优先级,并通过ERPMT实现最终的无线传感网络优化。针对不同分布类型网络寿命的实验验证了本文算法的有效性及可靠性,实验结果表明,相比较为先进的启发式方法CMAX及OML,本文算法明显增大了无线传感网络的覆盖范围,并且大大地延长了网络的寿命。     

螺旋线慢波结构高频特性的简化模拟方法

 利用3D电磁仿真软件HFSS中的Master/Slaver边界条件,基于螺旋线慢波结构的角向周期性,提出了一种改进的高频特性仿真方法。将具有3根夹持杆的螺旋线慢波结构的仿真模型从1个螺距的长度缩小到了1/3个螺距。仿真结果表明：采用改进后的模型,计算所得的相关高频特性参数与改进前传统模型所得结果基本一致,但是运算时间减少了至少3/4,且频率越高,计算时间上面的优势越大。     

三项指数和四次均值的精确计算公式(2)

本文进一步深入研究了三项指数和四次均值的计算问题.运用指数和的相关性质并结合求解同余方程组的方法与技巧,利用两种不同的方法获得了两个精确的均值计算公式,揭示了三项指数和的计算与同余方程组解的个数之间的本质联系,推广了已有的结果.     

大功率固态功放合成效率研究

应用散射参数理论对大功率合成器的合成效率进行了计算推导,分析了合成效率的各种影响因素,推导出合成效率所能达到的最大值,并且给出最大合成效率的条件.这对于进行S频段连续波800 W固态功放研制打下很好的理论基础.     

基于介质集成悬置槽线的差分至单端功分器北大核心CSCD

设计了一种基于介质集成悬置槽线的宽带差分至单端功分器。采用槽线与微带线耦合的差分过渡结构,实现了差分电路与单端电路的互连。在较宽的工作频率范围内实现了较好的共模噪声抑制。在10.52~15.58 GHz的频率范围内,测得差分端口处的回波损耗优于10 dB。输出端口在10.1~15 GHz的频率范围内保持15 dB以上的隔离度。差分工作模式下,功分器输出的两路信号具有幅值相等、相位相反的特点。所设计的电路基于多层板结构,将槽线及其核心电路悬置于多层板内置的腔体中,具有自封装、低辐射损耗等优势。     

基于“站-线-变-户”电网模型的预约停电管理模型设计

本文基于营配信息集成“站-线-变-户”电网模型,让客户参与停电计划的制定,在供电企业客服信息与互动平台实行预约停电。建立预约停电管理模型,即筛选预约停电客户群,选择最佳服务渠道与客户进行沟通,汇集分析各渠道客户的意见,通过算法处理制定最优的停电计划。