含间隙和尺寸误差空间连杆引纬机构运动精度综合分析

为分析间隙和尺寸误差对引纬机构运动精度的影响,详细介绍了非连续接触模型和等效杆长理论的使用方法,针对空间连杆引纬机构中的空间四杆机构和平面四杆机构,在考虑制造误差和磨损或装配间隙的情况下,以概率分析方法和非连续接触理论为基础建立了运动学模型。运用MatLab的计算和仿真模块进行运动仿真,得出了相关曲线。详尽分析了机构的尺寸误差和间隙对整个机构运动输出的影响,在考虑构件误差和运动副之间的间隙影响时,剑头的输出误差比单独考虑一种影响因素时明显,且误差最大值都出现在速度的极大值点附近,可见间隙和构件误差对高速机构的影响尤为严重,此研究结果可为后续对空间连杆引纬机构的运动精度分析提供参考。     

双波段频率选择表面复合材料的性能研究

以三阶正十字分行贴片旋转45°得到的图形为基本周期单元,设计了一种新型周期图案的频率选择表面(FSS)。将FSS和聚甲基丙烯酰亚胺泡沫复合制备得到双波段频选复合材料,通过对频率选择表面尺寸和泡沫厚度的设计,研究了其在1～18 GHz内的电磁波插损。研究结果表明,当FSS厚为12 μm,边界宽为30 μm,两侧泡沫厚为5 mm时,双波段频率选择超材料在特定的频段内电磁波插损的实验值和仿真值基本一致,即在2.5~35 GHz及8.5~11 GHz频段内,90%频点插损值小于0.9 dB;随着电磁波入射角的偏移,带内插损值增大,有效带宽减小。     

A strictly nonblocking network based on nonblocking 4×4 optical switches

Recently, the demand for communication has been growing rapidly. Hence, optical multistage network technologies are more appreciated nowadays. A double-layer network is a strictly nonblocking network, and it has the lowest system insertion loss of non-dilated networks. A Beneš network is a rearrangeably nonblocking network, and it has the same system insertion loss as a double-layer network. We have proposed the use of modified polarization selection elements (PSEs). The system insertion loss, number of drivers, and number of required components of a double-layer network could be reduced if it is constructed with modified PSEs. A nonblocking 4×4 optical switch with two stages of polarization selective elements has been presented in our previous study. Based on this nonblocking 4×4 optical switch, we propose a strictly nonblocking network structure which features even lower system insertion loss than those of a double-layer network and a Beneš network. The signal-to-noise ratio of the proposed network structure is a constant, and is higher than the constraint, although it is lower than that of the double-layer network. The number of major components of the proposed network is less than that of a double-layer network and larger than that of a Beneš network, since a Beneš network is rearrangeably nonblocking. We also offer a routing algorithm for the new proposed network; the time complexity of the routing algorithm is O(1).     

低插入损耗多通道介质膜型光波分复用器

介绍了一种采用新型多级均衡方案的介质膜型光波分复用器。该波分复用器具有低插入损耗和插入损耗均匀性好的特性。在与阵列波导光栅(AWG)型器件的竞争中具有更多的优势,从而使介质膜型器件可以成为目前光通信系统中制作密集波分复用(DWDM)器件的主流技术。     

高隔离度宽频段组合式RF-MEMS开关的设计

接触式与电容耦合式两类RF MEMS开关各自在一定的频段内,都具有较高的隔离度,但仍然很难满足微波控制系统中对高隔离度的要求.为了获得全波段高隔离度RF MEMS开关,单元开关很难达到要求,在此目标要求下,提出了组合式RF MEMS开关的设计,分别利用HFSS软件对各单元进行结构参数优化,再将两者集成在一起,得到的组合式RF MEMS开关,这种组合式开关在0～20 GHz时隔离度都高于-60 dB,在(≤5 GHz),隔离度高于-70 dB,这是一般单元开关及其他半导体固态开关所无法企及的,而且,在DC～20 GHz范围内,开关的插入损耗小于-0.20 dB,而且并没因隔离度的提高,牺牲了插入损耗.     

纠正DPPM中插入删节错误的纠错码方案

采用差分脉冲位置调制（DPPM）的无线光通信中存在插入和删节错误。针对该类错误,提出了一种可纠正同步错误的编译码方案。DPPM的码片翻转会造成当前符号中比特的插入/删节及后续符号中比特的替代错误,替代错误总是伴随插入／删节错误发生。针对这种特殊的错误形式,通过删剪卷积码扩展网格图中的禁用路径,设计了改进的维特比译码算法。该方案不需要改变已有的卷积码编码方法,所设计系统的发端和传统的发端一致。结果表明,相比于未编码系统。所提出方案可有效降低误帧率．获得明显的性能增益。     

Molecular Insertion: A Master Key to Unlock Smart Photoelectric Responses of Covalent Organic Frameworks

Covalent organic frameworks (COFs) show potentials in prominent photoelectric responses by judicious structural design. However, from the selections of monomers and condensation reactions to the synthesis procedures, the acquisition of photoelectric COFs has to meet overmuch high conditions, limiting the breakthrough and modulation in photoelectric responses. Herein, the study reports a creative “lock-key model” based on molecular insertion strategy. A COF with suitable cavity size, TP-TBDA, is used as the host to load guests. Merely through the volatilization of mixed solution, TP-TBDA and guests can be spontaneously assembled via non-covalent interactions (NCIs) to produce molecular-inserted COFs (MI-COFs). The NCIs between TP-TBDA and guests acted as a bridge to facilitate charge transfer in MI-COFs, unlocking the photoelectric responses of TP-TBDA. By exploiting the controllability of NCIs, the MI-COFs can realize the smart modulation of photoelectric responses by simply changing the guest molecule, thus avoiding the arduous selection of monomers and condensation reactions required by conventional COFs. The construction of molecular-inserted COFs circumvents complicated procedures for achieving performance improvement and modulation, providing a promising direction to construct late-model photoelectric responsive materials.     

基于低电压驱动MEMS的可调光衰减器的设计与性能分析

研制了一种低成本、小体积的静电驱动微电机系统（MEMS）可调光衰减器（VOA）。该器件采用了静电驱动微反射镜和光纤光准直器，它具有良好的光学性能，克服了传统VOA的缺点。它的驱动电压范围是0～8V，工作范围是0～25dB。给出了器件的衰减量和驱动电压的关系、光学性能的分析和试验结果。     

电极插入不同深度下稀土电解槽电热场耦合模拟

运用数值模拟软件COMSOL研究了不同电极插入深度下3kA钕电解槽的电热场。结果表明,电解槽槽电压随着阴阳极插入深度的递增而降低,槽体的整体温度随着阴阳极插入深度的增加而下降。结合实际生产经验与本研究结果,认为电极插入深度220mm比较适宜,且整个电解过程相对稳定,能够达到槽体电压、温度分布等方面的要求。     

AV3611网络分析仪应用

文中介绍了一种利用国产ＡＶ３６１１分析仪和ＨＰ８３５０Ｂ扫频信号源配置成一套网络分析仪的方法及其使用说明。