并行高阶矩量法分析大型阵列天线的辐射特性

随着计算机多核技术和计算机集群技术的发展,并行高阶矩量法可以解决复杂大型目标的电磁特性。文中首 先对单个天线单元在高阶矩量法与有限元方法下的结果进行对比,验证了本文方法的正确性和可行性,然后给出了一 个36×12 单元的伞形印刷振子天线阵列的方向图结果,从而说明了本文方法可以处理实际工程中的大规模挑战性问 题。     

High‐Performance Piezoelectric,Pyroelectric, and Triboelectric Nanogenerators Based on P(VDF‐TrFE) with Controlled Crystallinity and Dipole Alignment

Poly(vinylidenefluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)), as a ferroelectric polymer, offers great promise for energy harvesting for flexible and wearable applications. Here, this paper shows that the choice of solvent used to dissolve the polymer significantly influences its properties in terms of energy harvesting. Indeed, the P(VDF‐TrFE) prepared using a high dipole moment solvent has higher piezoelectric and pyroelectric coefficients and triboelectric property. Such improvements are the result of higher crystallinity and better dipole alignment of the polymer prepared using a higher dipole moment solvent. Finite element method simulations confirm that the higher dipole moment results in higher piezoelectric, pyroelectric, and triboelectric potential distributions. Furthermore, P(VDF‐TrFE)‐based piezoelectric, pyroelectric, and triboelectric nanogenerators (NGs) experimentally validate that the higher dipole moment solvent significantly enhances the power output performance of the NGs; the improvement is about 24% and 82% in output voltage and current, respectively, for piezoelectric NG; about 40% and 35% in output voltage and current, respectively, for pyroelectric NG; and about 65% and 75% in output voltage and current for triboelectric NG. In brief, the approach of using a high dipole moment solvent is very promising for high output P(VDF‐TrFE)‐based wearable NGs.     

Synchronization based on preamble symbol for DVB-T2 system

DVB-T2（digita1 video broadcasting-second generation terrestria1）system adopted a preamb1e,with a specia1 C-A-B structure,to accomp1ish time-frequency synchronization.A11 existing preamb1e based synchronization a1gorithms on1y uti1ized the corre1ation between C and A or B and A,neg1ecting the conjugate symmetry character within A.By using this character,a new synchronization method was proposed to make detection probabi1ity higher and synchronization error sma11er.Monto Car1o simu1ations were carried out in AWGN（addictive white Gaussian noise）channe1 and TU6（typica1 urban）channe1 with ve1ocity of 30 km/h.Compared with existing synchronization methods,both higher detection probabi1ity and sma11er mean square error in time-frequency synchronization is achieved.     

一种适用于高速接口电路的新型均衡电路

本文提出了一种新型高速均衡电路.在传统源极负反馈均衡滤波结构的基础上改进电路结构,使用有源电感及对称负载结构改善了电路性能,避免了使用片上电感,优化了电路结构,节省了芯片面积,同时缓解了传统均衡电路的速度瓶颈.经仿真验证,该均衡器电路高频补偿增益达到17.2dB ,高低频增益比达到5.24,信号速率达到5Gb/s 时能完整接收信号,实现均衡效果.该电路结构简单,适用于各种高速信号接口电路.该电路采用0.13μm CMOS 工艺实现.     

基于或-符合运算Reed-Muller展开系数的对称变量检测算法

针对或-符合代数系统中缺失对称变量检测的有效方法等问题,提出了该代数系统基于或-符合运算Reed-Muller展开系数的十二类变量对称性检测算法。该算法通过分析逻辑函数关于变量xi、xj展开的子函数系数矩阵和或-符合运算Reed-Muller展开系数按变量xi、xj组合分解系数矩阵的对应关系,揭示了任意两变量间各类对称性所满足的分解系数矩阵的约束条件,提出了各类逻辑变量的对称性检测步骤。应用结果表明,与传统方法相比,免去了从逻辑函数的CRM展开式变换为最小项展开式或RM展开式的变换域转换过程,也解决了在该域中图形方法检测的完备性问题,具有简单、直观、完备及适合计算机编程等优点。     

电磁定位系统测量误差校正技术研究

在电磁定位系统中, 若没有考虑环境磁场、制造工艺等误差因素的影响, 会导致系统定位精度下降。介绍了一种提高电磁定位系统定位精度的方法, 该方法为了克服经典磁偶极子模型过于理想化的缺点, 提出了误差修正模型, 介绍了天线参数标定原理, 同时给出了修正因子的标定方法、标定流程以及装置。通过对比试验可以看出, 经过模型修正的系统定位精度可达到未修正模型的5倍。     

一种新型目标图像去模糊方法

针对现有的图像去模糊法存在着细节纹理失真、锐化效果不显著、平滑区域去模糊效果欠佳等不足,提出一种基于自适应阈值和改进梯度算子的新方法,该法首先对原图像素进行全扫描提取得到自适应阈值,然后建立像素点增强方程,再将增强后的点进行新梯度算子滤波,最后重组像素得到增强图像,仿真结果验证了该法在增强锐化的同时,保护了图像的细节和平滑区域像素等信息.     

具有梯形有源振子的印刷引向天线研究

设计了一种采用平衡微带线馈电的具有梯形有源振子的印刷引向天线。对梯形印刷有源振子的阻抗特性进行了仿真,在此基础上进行了改进,首先是有源振子加载反射器,然后是有源振子加载引向器和反射器。仿真了天线的阻抗特性和辐射特性,并分别制作了天线实物进行测试。仿真与实验结果表明,有源振子加载引向器和反射器后的工作频带为2.0~2.45GHz,相对带宽达20.2%,带内增益为6dB 左右,且具有较小的尺寸（60 mm×65 mm）,可用于移动通信领域。     

Long‐Range Domain Structure and Symmetry Engineering by Interfacial Oxygen Octahedral Coupling at Heterostructure Interface

In epitaxial thin film systems, the crystal structure and its symmetry deviate from the bulk counterpart due to various mechanisms such as epitaxial strain and interfacial structural coupling, which is accompanyed by a change in their properties. In perovskite materials, the crystal symmetry can be described by rotations of sixfold coordinated transition metal oxygen octahedra, which are found to be altered at interfaces. Here, it is unraveled how the local oxygen octahedral coupling at perovskite heterostructural interfaces strongly influences the domain structure and symmetry of the epitaxial films resulting in design rules to induce various structures in thin films using carefully selected combinations of substrate/buffer/film. Very interestingly it is discovered that these combinations lead to structure changes throughout the full thickness of the film. The results provide a deep insight into understanding the origin of induced structures in a perovskite heterostructure and an intelligent route to achieve unique functional properties.     

本质安全型防爆摄像仪的研发和应用

高清4G公网防爆摄像仪系统是为石油化工等高危防爆环境研制的便携移动防爆摄像系统。如何在高清4G模块高发射功率、多储能元件的前提下实现设备的总体防爆指标以满足国家标准是本文解决的重点问题。基于防爆理论,通过提高设备防爆电容设计门限和降低电路容值设计的电容管理手段,对整体设备的储能元件进行了极限防爆限制,优化设计了4G-LTE无线摄像模块的最低储能电容解决方案;利用双半波振子天线列阵技术实现天线设备的发射功率限制硬件保护,采用软件保护手段实现双重防爆保护,从设计原理上保证了研发的高清4G摄像仪满足《GB 3836.1-2000》防爆要求。在保证防爆性能和设备功能的前提下,设备电容容量降低了50%,设备远场电场强度9%。