机载光电雷达它机试飞技术研究

机载光电雷达受平台及大气环境影响较大,而它机试飞能有效规避研制风险,是产品研制的必经阶段。本文介绍了机载光电雷达它机试飞试验系统组成、试验流程和数据处理等内容。经工程验证,实施过程满足任务需求,对其他光电系统的它机及本机试飞具有参考价值。     

雷达发射机浮动板调制器与故障检测电路的设计

提出了一种改进的浮动板调制器和对正负偏电压的故障检测电路,利用MOSFET寄生电容特性,通过固定脉宽窄脉冲控制调制脉宽,通过增加负偏MOSFET提高输出负偏电压。对故障检测电路进行仿真实验,通过模拟故障,验证故障检测报警信号发生时间均在微秒级别。完成样机的搭建,利用多重方式解决高压绝缘问题,并对其加电进行试验验证,分析实验波形,证明此电路满足设计要求并且具有可行性。     

Enhanced hydrogen storage performance of three-dimensional hierarchical porous graphene with nickel nanoparticles

Three-dimensional hierarchical porous graphene with nickel nanoparticles (3DHPG-Ni) was synthesized through electrostatic assembly method with the assistance of poly (methyl methacrylate) (PMMA) template and subsequent removal of PMMA template by calcination. The morphology, microstructure and hydrogen adsorption properties of 3DHPG-Ni nanocomposites were examined in detail. The obtained 3DHPG-Ni nanocomposite exhibited hierarchical porous structure composed of macro-, meso- and micropores, high specific surface area (925 m² g^?1), large pore volume (0.58 cm³ g^?1) and excellent hydrogen storage capacity. Under the pressure of 5 bar, 3DHPG-Ni nanocomposite showed a maximum hydrogen capacity of 4.22 wt% and 1.95 wt% at 77 K and 298 K, respectively, demonstrating that the as-prepared 3DHPG-Ni nanocomposite was supposed to be a promising material with outstanding properties for practical applications in the field of hydrogen storage. The three-dimensional hierarchical porous structure, evenly distributed Ni nanoparticles and hydrogen spillover effect were responsible for the enhanced hydrogen storage capacities.     

Synthesis and Preliminary Evaluation of 11C-Labeled VU0467485/AZ13713945 and Its Analogues for Imaging Muscarinic Acetylcholine Receptor Subtype 4

Muscarinic acetylcholine receptors (mAChRs) have five distinct subunits (M₁–M₅) and are involved in the action of the neurotransmitter acetylcholine in the central and peripheral nervous system. Attributed to the promising clinical efficacy of xanomeline, an M₁/M₄-preferring agonist, in patients of schizophrenia and Alzheimer's disease, M₁- or M₄-selective mAChR modulators have been developed that target the topographically distinct allosteric sites. Herein we report the synthesis and preliminary evaluation of ¹¹C-labeled positron emission tomography (PET) ligands based on a validated M₄R positive allosteric modulator VU0467485 (AZ13713945) to facilitate drug discovery. [¹¹C]VU0467485 and two other ligands were prepared in high radiochemical yields (>30 %, decay-corrected) with high radiochemical purity (>99 %) and high molar activity (>74 GBq μmol⁻¹). In vitro autoradiography studies indicated that these three ligands possess moderate-to-high in vitro specific binding to M₄R. Nevertheless, further physiochemical property optimization is necessary to overcome the challenges associated with limited brain permeability.     

System level design and analysis of a fourth‐order continuous‐time delta‐sigma modulator using relaxed gain‐band‐width amplifiers

In this paper, based on mathematical approaches and behavioral modeling of internal blocks, an algorithm of designing a continuous‐time delta‐sigma modulator (CT ΔΣM) with aggressive noise shaping is discussed. Using proposed methods, the coefficients of modulator can be calculated directly while the finite gain‐band‐width of amplifiers and rise/fall time of digital‐to‐analog convertors (DACs) in feedback path are included in the transfer function of CT loop filter. To decrease the number of amplifiers, a unique resonator is proposed. Also, an extra feedback DAC is introduced to further reduction of gain‐band‐width requirement of last amplifier. To verify the effectiveness of proposed methods, a fourth‐order, single loop, CT ΔΣM that benefits proportional‐integrator element for compensation of excess‐loop‐delay is realized in system and behavioral circuit levels. It has a 4‐bit quantizer, over‐sampling‐ratio of 10, and out‐of‐band‐gain of 12 dB. The peaking in signal‐transfer‐function is alleviated using a feed‐forward capacitor along with proper choosing of rest coefficients. The designed modulator has 78‐dB signal‐to‐noise‐ratio; even the non‐ideal behaviors of amplifiers and DACs are involved in simulations. Independent to sampling frequency, the proposed methods can be applied to other topologies of CT ΔΣMs. Copyright © 2017 John Wiley & Sons, Ltd.     

PUMA／ASPP1双抑癌基因对胃癌 SGC-7901细胞增殖的影响

目的：探讨 p53正向细胞凋亡调控因子（p53 up-regulated modulator of apoptosis protein,PUMA）／p53促凋亡蛋白（apoptosis stimulating protein of p53,ASPP）1融合基因及单个基因对胃癌 SGC-7901细胞的杀伤作用。方法通过脂质体（lipofectamine）2000TM 将 PUMA／ASPP1融合基因及 PUMA、ASPP1单个基因分别转染胃癌SGC-7901细胞系[实验设5组,分别为胃癌细胞无转染空白对照（SGC-7901）组,空载质粒转染细胞对照（SGC-7901-pcDNA3．1）组以及重组 ASPP1质粒转染细胞实验（SGC-7901-ASPP1）组、重组 PUMA 质粒转染细胞实验（SGC-7901-PUMA）组、重组 PUMA／ASPP1质粒转染细胞实验（SGC-7901-PUMA／ASPP1）组],再次经 G418筛选,获得稳定表达融合基因 SGC-7901-PUMA／ASPP1细胞株。通过 MTT 法及使用流式细胞仪测定各组胃癌SGC-7901系细胞的存活数（光吸收度即 A 值）及细胞周期。结果SGC-7901组与 SGC-7901-pcDNA3．1组 A 值比较差异无统计学意义（P ＞0．05）;SGC-7901-ASPP1组、SGC-7901-PUMA 组和 SGC-7901-PUMA／ASPP1组 A值明显低于 SGC-7901组与 SGC-7901-pcDNA3．1组（均 P ＜0．01）;SGC-7901-ASPP1组、SGC-7901-PUMA 组和SGC-7901-PUMA／ASPP13组中,SGC-7901-PUMA／ASPP1细胞组 A 值最低（P ＜0．01）。与 SGC-7901组、SGC-7901-pcDNA3．1组比较,SGC-7901-ASPP1、SGC-7901-PUMA、SGC-7901-PUMA／ASPP1组的 G1期明显增多,S 期明显减少,尤以 SGC-7901-PUMA／ASPP1组 S 期减少为甚（均 P ＜0．01）;SGC-7901-pcDNA3．1组与 SGC-7901组比较 G1期、S 期差异无统计学意义（P ＞0．05）。结论双抑癌基因可有效抑制胃癌 SGC-7901系细胞增殖,双抑癌基因较单个抑癌基因具有更强的抗肿瘤作用。     

高级引力波探测器的机遇和挑战

激光干涉仪引力波观测器已经完成建设,该观测器称为高级LIGO或aLIGO,与2002—2010年间使用的引力波搜寻设备相比,预期灵敏度可以提高一个数量级。目前aLIGO的调试正在试运行。为了达到提升灵敏度的要求,探测器中的所有元件需要提升水平。在此将讨论光电调制器和法拉第隔离器在平均功率百万瓦级分离高质量光束能力的发展,并详述它们在aLIGO输入光学系统中的作用。     

采用 DWA技术的多位Σ-Δ调制器的设计

设计一个内部采用2位量化器的二阶单环Σ‐Δ调制器．为解决反馈回路中多位DAC元件失配导致的信号谐波失真问题,该调制器采用了数据加权平均（Data Weighted Averaging ,DWA ）技术来提高多位DAC的线性度．Σ‐Δ调制器信号带宽为50 kHz ,过采样率（OSR）为64,采用MXIC公司的0．35μm混合信号CMOS工艺实现,工作电压为12 V ．后仿真结果显示,在电容随机失配5％的情况下,该调制器可以达到55．8 dB的信噪比（SNR）和60.4 dB的无杂散动态范围（SFDR）．打开DWA电路比关闭DWA电路的情况下,SNR和SFDR分别提高8 dB和13 dB ．整个调制器功耗为48 mW ,面积仅为0.6mm2．     

光电成像导引察打一体无人机命中精度计算分析

针对采用电视或红外成像导引方式的自毁式侦察打击一体化无人机,在落点偏差正态分布假定下,根据相对目标的以圆概率误差（CEP）表示的命中精度的定义,忽略无人机滚转影响,对CEP与落点系统偏差和标准偏差的关系进行数学描述。结合系统工作原理和俯冲攻击流程,建立CEP和基于视频图像的跟踪导引系统和随机角误差及导引盲距（即最短有效导引距离）间的数学方程,并利用Mathcard数学软件举例计算分析。此方法可以用于依据给定CEP和导引盲距分解确定跟踪导引角误差参数,也可基于导引盲距和跟踪导引角误差预测CEP指标是否能够实现。     

基于开关管阻抗特性的调制组件检测方法

介绍了全固态调制器采用IGBT 管等固态器件进行串并联组合应用的典型工作模式,分析了固态调制器传统开关组件的检测和保护技术,提出基于开关管阻抗特性的调制组件检测方法,阐述了设计思想及工作原理,给出了工程实现方案和检测方法原理框图,并分析比较了传统的在线检测方法和基于开关管阻抗特性的调制组件检测方法,基于PLC 编程软件平台,根据采样电压的数值及其变化量,实现精确判定IGBT 管损坏数量和百分比的计算。工程应用验证了检测结果的准确可靠。