溶胶-凝胶K_(0.5)Bi_(0.5)TiO_3陶瓷的高温XRD研究

采用溶胶-凝胶法成功制备出K0.5Bi0.5TiO3(KBT)纳米微粉,并利用此微粉烧结出成瓷良好的KBT陶瓷。用XRD法测定了KBT陶瓷粉末室温和高温(600°C)时的点阵常数,确定KBT的高温相为立方结构(点群为m3m)并指标化其衍射线,给出了KBT陶瓷粉末的多晶XRD数据。     

新型非PWM功率单元在完美无谐波高压变频器中的应用

本文对完美无谐波高压变频器的结构原理和其内部的普通PWM功率单元结构及原理进行了简要的介绍,在此基础上阐释了一种新型的应用于完美无谐波高压变频器的非PWM功率单元,并对其电路结构,工作原理以及特点优势进行了介绍,展示了仿真试验结果,说明了其基于DSP的实现方法。     

High Temperature Superconducting Magnetic Energy Storage and Its Power Control Technology

High temperature superconducting （HTS） power inductor and its control technology have been studied and analyzed in the paper. Based on the results of simulations and practical experiments, a controlled release scheme has been proposed and verified for developing a practical HTS SMES prototype.     

Alignment of a Perylene‐Based Ionic Self‐Assembly Complex in Thermotropic and Lyotropic Liquid‐Crystalline Phases

The thermotropic and lyotropic liquid‐crystalline (LC) phases of the ionic self‐assembled complex N,N′,‐bis(2‐(trimethylammonium)ethylene)‐perylene‐3,4,9,10‐tetracarboxyldiimide‐bis(2‐ethylhexyl)sulfosuccinate have been studied using polarizing microscopy, differential scanning calorimetry (DSC), and X‐ray scattering techniques. A two‐dimensional (2D) columnar thermotropic LC phase with π–π stacking of the perylene tectonic units and a lyotropic LC phase in dimethyl sulfoxide (DMSO) have been found. Different techniques have been applied to align both systems and included: surface interactions, electric and magnetic fields, shear force, and controlled domain formation at the LC–isotropic phase‐transition front (PTF). Characterization of the alignment in films has been performed using polarized UV‐vis spectroscopy and transmission null‐ellipsometry. The best results have been obtained for alignment of the material in a lyotropic phase by controlled domain formation at the PTF of the LC–isotropic phase transition. In this case, a dichroic ratio of 18 is achieved with packing of columns of perylenediimide tectons perpendicular to the PTF.     

A Framework for MPEG‐4 Contents Delivery over DMB

Digital Multimedia Broadcasting (DMB) is an upcoming standard in Korea used to provide mobile multimedia broadcasting service based on the Eureka‐147 Digital Audio Broadcasting (DAB) system. The current dominant multimedia coding standard, MPEG‐4, is foreseen to play an important role in forthcoming DMB services. However, the current approaches for transporting MPEG‐4 content over DMB networks are not optimized. To address this issue we propose a novel MPEG‐4 stream multiplexer, called M4SMux, which provides better stream multiplexing and delivery over DMB networks. M4SMux features an MPEG‐4 elementary‐stream interleaving mechanism that reduces the multiplexing overhead and a multiplex configuration mechanism that utilizes M4SLinkTable for easy content access. In addition, we propose an error correction method which enhances transport efficiency.     

多硝基3,3,7,7-四（三氟甲基）-2,4,6,8-四氮杂双环[3.3.0]辛烷的合成与性能

为了探索三氟甲基对含能材料性能的影响,以偕二氨基六氟丙烷和乙二醛为原料构建了氮杂稠环类含能材料的硝化前体——3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷,通过改进的合成路线,用发烟硝酸多步硝化分别得到2,6-二硝基-3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷(4)、2,4,6-三硝基-3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷(5)和2,4,6,8-四硝基6-3,3,7,7-四(三氟甲基)-2,4,6,8-四氮杂双环[3.3.0]辛烷(6)。利用核磁共振氢谱、碳谱和氮谱表征了产物结构;采用排惰性气体法测试了三种硝化产物的密度,其中6的密度最大,高达2.08 g·cm~(-3);分别用落锤升降法和BAM法测得三种产物的撞击感度均大于30 J、摩擦感度均大于360 N;热重-微商热重(TG-DTG)分析发现三种产物的质量损失均大于90%,其热稳定性随硝基的增加而下降;利用Gaussian 09计算包,通过Monte-Carlo统计学方法以及Kamlet-Jacbos方程和VLW爆轰产物状态方程等理论模型预估了产物的爆速、爆压,其中化合物6的爆速为1 1937 m·s~(-1),爆压为74.3 GPa。与四硝基甘脲(TNGU)的性能及感度对比发现,在含能材料的分子结构中引入具有更高密度和更大电负性的三氟甲基,可在维持较高密度和良好爆轰性能的同时降低感度。     

某型混联微光像增强器增益漂移问题研究

为解决某型混联微光像增强器在生产过程中出现高、低温增益超占比较高的问题,分析像增强器增益产 生温度漂移的原理,研究常温、低温和高温条件下的增益变化规律,并采用Minitab 软件分析像增强器的增益与温 度相关性,拟合出增益-温度回归函数,据此确定常温增益的调节范围。结果表明：该方法能降低该型微光像增强器 增益漂移超范围的风险,有效提高产品质量。     

提高低燃速丁羟推进剂力学特性研究

大量粗粒度AP和降速剂的添加很难实现低燃速丁羟推进剂高强度的技术要求。研究以静态燃速不高于5.1 mm/s(20℃,6.0 MPa)低燃速丁羟推进剂作为基础配方,通过优选HTPB规格、键合剂组合和添加新型扩链剂的方法提高推进剂力学特性。结果表明,采用新型扩链剂SX,使70℃推进剂的抗拉强度高于1.0 MPa,伸长率大于10%。     

基于RCM 的导弹装备最佳预防性维修周期决策

针对目前确定预防性维修周期时存在不确定性的问题,建立了基于RCM的导弹装备维修周期决策模型。分别以总费用最小和可用度最大为目标建立导弹装备维修周期决策模型,采用蒙特卡罗仿真进行模型求解,采用模糊决策方法确定多目标综合最佳预防性维修周期,并以某型导弹装备密封圈为例,验证方法的有效性。实践分析结果表明:该方法综合权衡了费用和可用度因素,能较好地解决可用度低下且维修费用居高不下的问题,有一定应用和参考价值。     

火箭橇试验地面点火控制系统

在发动机寄留释放火箭橇试验中,需同时验证被试发动机静态、动态2 种工作状态。为精确控制被试发 动机及其他火工品,使其能按预设时间依次工作,设计地面多路时序点火控制系统。详细介绍硬件设计,在此基础 上给出主控芯片内部的工作流程及设计方法,并进行试验验证。结果表明：该系统攻克了高精度时序控制、多路大 电流驱动输出、多路输出信号间串扰和环境适应性等关键技术,能实现对弹上多种指令和多级火工品的点火控制。