多雷达空间目标协同探测任务规划研究

针对空间目标监视存在各传感器资源相互独立,预警资源得不到有效利用,导致空间目标探测时长不够、探测精度低等问题,提出了一种多雷达空间目标协同探测的任务规划方法,综合利用多个雷达传感器资源对空间目标进行协同探测,最终达到在短时间内累积足够的多圈有效探测数据进行协同探测的目的。文中通过对任务目标分析、资源编组、可探测性分析、弧段筛选分配等关键性技术进行分析,具体阐述了解决问题的方法。该任务规划方法在解决上述空间目标探测问题的同时可以大大节省雷达资源。     

一种多基地雷达抗距离欺骗干扰技术

针对距离多假目标欺骗干扰下多基地雷达系统,提出一种基于同源定位检验的抗欺骗干扰技术。首先,各接收站对获取到的目标角度量测进行预处理,划分出同一方位向上目标并进行数据压缩,以此提高同一方向上目标角度量测精度;同时,利用发射站和接收站组成的双基地雷达系统进行目标定位;最后,将各站定位结果进行同源定位检验,并融合检验后结果。仿真结果表明:该方法能有效抑制距离多假目标欺骗干扰,并能对多目标进行精确定位。     

Efficient Infrared Solar Cells Employing Quantum Dot Solids with Strong Inter-Dot Coupling and Efficient Passivation

Lead chalcogenide quantum dot (QD) infrared (IR) solar cells are promising devices for breaking through the theoretical efficiency limit of single-junction solar cells by harvesting the low-energy IR photons that cannot be utilized by common devices. However, the device performance of QD IR photovoltaic is limited by the restrictive relation between open-circuit voltages (V_OC) and short circuit current densities (J_SC), caused by the contradiction between surface passivation and electronic coupling of QD solids. Here, a strategy is developed to decouple this restriction via epitaxially coating a thin PbS shell over the PbSe QDs (PbSe/PbS QDs) combined with in situ halide passivation. The strong electronic coupling from the PbSe core gives rise to significant carrier delocalization, which guarantees effective carrier transport. Benefited from the protection of PbS shell and in situ halide passivation, excellent trap-state control of QDs is eventually achieved after the ligand exchange. By a fine control of the PbS shell thickness, outstanding IR J_SC of 6.38 mA cm⁻² and IR V_OC of 0.347 V are simultaneously achieved under the 1100 nm-filtered solar illumination, providing a new route to unfreeze the trade-off between V_OC and J_SC limited by the photoactive layer with a given bandgap.     

Interfacial Engineering of Bifunctional Niobium (V)-Based Heterostructure Nanosheet Toward High Efficiency Lean-Electrolyte Lithium–Sulfur Full Batteries

High-efficiency lithium–sulfur (Li–S) batteries depend on an advanced electrode structure that can attain high sulfur utilization at lean-electrolyte conditions and minimum amount of lithium. Herein, a twinborn holey Nb₄N₅–Nb₂O₅ heterostructure is designed as a dual-functional host for both redox–kinetics–accelerated sulfur cathode and dendrite-inhibited lithium anode simultaneously for long-cycling and lean-electrolyte Li–S full batteries. Benefiting from the accelerative polysulfides anchoring–diffusion–converting efficiency of Nb₄N₅–Nb₂O₅, polysulfide-shutting is significantly alleviated. Meanwhile, the lithiophilic nature of holey Nb₄N₅–Nb₂O₅ is applied as an ion-redistributor for homogeneous Li-ion deposition. Taking advantage of these merits, the Li–S full batteries present excellent electrochemical properties, including a minimum capacity decay rate of 0.025% per cycle, and a high areal capacity of 5.0 mAh cm⁻² at sulfur loading of 6.9 mg cm⁻², corresponding to negative to positive capacity ratio of 2.4:1 and electrolyte to sulfur ratio of 5.1 µL mg⁻¹. Therefore, this work paves a new avenue for boosting high-performances Li–S batteries toward practical applications.     

Precise measurement of gold nanorods by using depolarized dynamic light scattering apparatus

A precise and noninvasive method for the size and shape measurement of gold nanorods(GNRs) has been proposed based on depolarized dynamic light scattering(DDLS). A home-made DDLS apparatus has been established. By applying depolarized optical path with precise alignment method, the signal-to-noise ratio(SNR) of this apparatus is highly improved. GNRs with three different diameter and length has been precisely measured by using DDLS method as well as scanning electron microscopy(SEM). The thickness of adsorption layer of cetyltrimethylammonium bromide(CTAB) in solution has been taken into consideration. Results show that size measurement of GNRs by using DDLS method agrees very well with that by using SEM. In addition, it is shown that the extinction spectroscopy strongly limited the application of DDLS method by affecting the effective scattering light intensity. Proper laser wavelength should be chosen before the application of this method.     

一种面向移动边缘计算的多用户细粒度任务卸载调度方法

在移动边缘计算中(Mobile Edge Computing,MEC),任务卸载可以有效地解决移动设备资源受限的问题,但是将全部任务都卸载到边缘服务器并非最优.本文提出一种面向移动边缘计算的多用户细粒度任务卸载调度新方法,把计算任务看作一个有向无环图(Directed Acyclic Graph,DAG),对节点的执行位置和调度顺序进行了优化决策.考虑系统的延迟把计算卸载看作一个约束多目标优化问题(Constrained Multi-object Optimization Problem,CMOP),提出了一个改进的NSGA-Ⅱ算法来解决CMOP.所提出的算法能够实现本地和边缘的并行处理从而减少延迟.实验结果表明,算法能够在实际应用程序中做出最优决策.     

一种引力波探测用高灵敏度四象限光电探测器

针对引力波探测空间天线激光干涉仪对四象限光电探测器提出的低噪声、高灵敏度、高带宽的要求,设计了一种四象限光电探测器芯片与读出电路混合集成的低噪声光电探测器.四象限光电探测器芯片采用四个性能一致的双耗尽区InGaAs PIN光电二极管单片集成结构,以降低二极管电容,减小象限间隔,提高灵敏度.通过PSPICE软件对由探测器芯片、低噪声跨阻放大读出电路构成的探测器模块进行了仿真,优化了电路参数,计算出相应的增益、带宽、噪声功率密度.性能测试表明,研制的集成式探测器模的-3 dB带宽为28.3 MHz,等效噪声功率密度为1.7pW/Hz1/2,象限增益一致性为0.76％,基本满足空间激光干涉仪的需求.     

用于太赫兹成像的CMOS肖特基二极管三维结构

提出了一种简单、科学、有效的高截止频率肖特基势垒二极管设计方法。通过SMIC 180 nm工艺制备的肖特基二极管的截止频率为800 GHz,分析测试结果和仿真数据优化后的肖特基势垒二极管截止频率可以达到1 THz左右。完成了包括天线、匹配电路和肖特基势垒二极管的集成探测器,在220 GHz下其测试响应率可达130 V/W,等效噪声功率估计为400 pw/。完成了陶瓷瓶内不可见液面的成像实验并取得了良好的效果。     

基于噪声样本的结构风险最小化原则

统计学习理论中的结构风险最小化原则比经验风险最小化原则的实用性更强,对结构风险最小化原则的研究多是在样本不受噪声影响前提下进行的.基于此,给出零均值噪声样本的函数集容量的相关概念,并讨论了基于VC维的收敛速度的界,给出零均值噪声样本的结构风险最小化原则,为进一步研究概率空间上噪声样本的学习理论提供了理论基础.     

基于FPGA的导管式超声治疗系统设计

导管式超声在临床治疗上受到广泛关注。为实现方便、稳定的导管式超声激励系统,该文基于直接数字频率合成（DDS）技术在现场可编程门阵列（FPGA）上,设计了一款由上位机控制,波形、频率、占空比和电压幅值可灵活调节的导管式超声治疗系统,实现了脉冲激励信号的输出。测试表明,该系统人机交互方便,参数灵活,输出波形稳定,实现了对微型超声换能器的激励要求。用该系统对定制的超声换能器进行激励,实验测试了超声作用下仿体的温升情况。结果表明,该系统可有效激励超声换能器实现仿体内特定区域的热消融。