基于WVD-HT的SAR/ISAR多运动目标检测

本文提出和研究了基于Wigner-Ville分布(WVD)和Hough变换(HT)的合成孔径雷达(SAR)和逆合成孔径雷达(ISAR)对多运动目标成象的运动补偿新方法,给出了多运动目标检测、参数估算和运动补偿的主要步骤。理论分析、计算机和微波暗室模拟实验的结果表明,新方法对交叉项和噪声的抑制是有效的,它与单一的WVD法相比,提高了在噪声中对单个和多个运动目标检测及其参数估算的能力。     

高速多芯片组件同步开关噪声的二维特征法全波分析

高速多芯片组件(MCM)广泛用于高复杂度的系统中,而其中的同步开关噪声(Simultaneous Switching Noise)是影响系统功能的重要因素.本文采用二维电磁模型模拟MCM电源、接地板同步开关噪声;文中提出一种新的时域电磁问题的数值方法特征法,并用于求解上述问题,所得结果与FD-TD计算的结果和文献报道一致.     

Non-line-of-sight ultraviolet single-scatter path loss model

A novel non-line-of-sight ultraviolet single-scatter path loss model for coplanar geometries is proposed on the basis of spherical coordinate system. In comparison with the classical single-scatter analytical model based on the prolate-spheroidal coordinate system, it is of a simple integral form which only depends on the variables of the zenith and receiver elevation angles. Additionally, analytical approximation for the proposed single-scatter path loss model is presented. Numerical examples on path loss are presented for various system geometries. Correspondingly, the results are verified with the classical single-scatter analytical model, which demonstrates the validity of our path loss model and the reasonability of the analytical approximation.     

Peripheral Nerve‐Derived Matrix Hydrogel Promotes Remyelination and Inhibits Synapse Formation

Regeneration of injured nerve tissues requires intricate interplay of complex processes like axon elongation, remyelination, and synaptic formation in a tissue‐specific manner. A decellularized nerve matrix‐gel (DNM‐G) and a decellularized spinal cord matrix‐gel (DSCM‐G) are prepared from porcine sciatic nerves and spinal cord tissue, respectively, to recapitulate the microenvironment cues unique to the native tissue functions. Using an in vitro dorsal root ganglion–Schwann cells coculture model and proteomics analysis, it is confirmed that DNM‐G promotes far stronger remyelination activity and reduces synapse formation of the regenerating axons in contrast to DSCM‐G, Matrigel, and collagen I, consistent with its tissue‐specific function. Bioinformatics analysis indicates that the lack of neurotrophic factors and presence of some axon inhibitory molecules may contribute to moderate axonal elongation activity, while laminin β2, Laminin γ1, collagens, and fibronectin in DNM‐G promote remyelination. These results confirm that DNM‐G is a promising matrix material for peripheral nerve repair. This study provides more insights into tissue‐specific extracellular matrix components correlating to biological functions supporting functional regeneration.     

脉冲激光热力冲击效应对电沉积的作用

脉冲激光电化学复合沉积利用激光的热力冲击效应可以有效提高沉积效率,改善加工质量。在所构建的纳秒脉冲激光电化学沉积加工系统中,利用激光辐照和电化学沉积的方法对铜进行了复合沉积试验。分析了激光的热力冲击效应对电沉积的作用机理,激光产生的力效应使阴极基片发生弹性变形,改变了电极电势和电流密度,提高了电沉积质量。通过加工试验,研究了激光平均功率密度对沉积质量和沉积效率的影响,并进行了讨论。试验结果表明,激光平均功率密度介于100~400 kW/cm2时可以获得较好的沉积层质量。激光平均功率密度在200 kW/cm2左右,沉积速率取得最大值。     

RTD/HEMT串联型共振隧穿三极管的设计与研制

对RTD/HEMT串联型共振隧穿三极管进行了设计和研制.测量结果表明:最大电流峰谷比为17.6∶1,棚压对峰值电压调控能力在1.5～7.7范围内,-3dB截止频率为4GHz,此种器件可与HEMT在结构和工艺上兼容,可应用于HEMT高速电路.     

SiGe共振腔增强型探测器的制备

利用SOI材料的埋层二氧化硅的自停止特性,成功制作了具有高反射底镜的共振腔增强型SiGe探测器.底镜沉积于EPW腐蚀液腐蚀形成的背孔内,在1.2～1.5μm范围内,反射率高达99%.探测器的共振峰在1.344μm,光响应为1.2mA/W.与普通结构的探测器相比,文中所报道的探测器光响应有8倍的增强.     

机载SAR系统平台运动容差分配方法

合成孔径雷达(SAR)系统平台运动容差分配是系统要求分配的一个重要方面,它是系统设计中的必要步骤,通过考虑误差源、误差影响和性能极限等因素使得最终的设计方案更为合理。该文在分析和仿真平台运动误差对SAR成像质量的影响的基础上,提出了一种机载SAR系统平台运动容差分配的方法:根据实际成像系统和成像环境搭建仿真平台后,通过仿真实验逐步得到独立运动误差容限、联合运动误差容限和修正运动误差容限,最后考虑一些相关因素在前面仿真所得的容限区域上合理地做出平台运动容差分配的最后决策。这种方法将系统的平台参数、平台运动误差的类型和方向、测绘宽度以及成像质量要求等因素均作为分配过程的约束条件,是一种兼具针对性和合理性的SAR系统平台运动容差分配方法。