5kW离子电推进大功率屏栅电源的设计研究

本文针对航天器用5kW离子电推力器核心供电模块屏栅电源的技术需求,采用移相全桥技术设计了低电压输入高电压输出的大功率屏栅电源模块。对比分析了ZVS和ZVZCS两种移相全桥方案后,得出ZVZCS更适合于电推进屏栅电源的设计。提出了ZVZCS移相全桥变换器CDD无损缓冲电路中辅助电容的设计方法,论述了屏栅电源功率级和控制电路的设计过程。通过实物产品验证表明：采用ZVZCS移相全桥技术设计的屏栅电源模块能在较宽的负载范围内实现超前桥臂和滞后桥臂的软开关,提高了变换器的效率;采用CDD无损缓冲电路能辅助实现滞后桥臂的零电流关断,降低原边电流的损耗,同时降低高压整流管的电压应力。在具备完善的输入滤波,浪涌抑制及母线开关等功能以后,最大功率下效率在95%以上。     

激光模切系统功率与运动的同步控制

通过对激光模切的加工中激光控制系统的设计、功率与运动速度的理论研究,并针对三种不同材料进行模切的数据分析,建立了函数关系.结合功率的PID闭环控制方法,实现了对二者的实时控制.最后对三种材料进行异形纸盒的模切实验切缝均匀、效果良好,使该算法得到了肯定.     

高精度光纤陀螺用ASE光源实验研究

本文主要介绍了高精度陀螺用ASE光源的几种基本光路结构,对单通前向光路结构进行了深入的实验研究,设计搭建了带滤波器的单通前向ASE光源光路。实验研究了铒纤长度、泵浦功率对光源性能的影响,并与国内某两个厂家光源的性能指标进行了对比分析,结果表明,自主研制的ASE光源各项指标达到预期要求,可以满足实际工程需要。     

高功率微波导弹发展现状分析研究

简要介绍了高功率微波武器的概念、毁伤机理、基本特点,对高功率微波武器的发展脉络进行了梳理.重点介绍了美国CHAMP高功率微波导弹的发展情况,对其可能的应用情况进行了探讨.     

小型SAR卫星用双高特性锂离子电池技术

小型合成孔径雷达(SAR)卫星对储能电池系统提出了轻量化、大功率的要求,现有的SAR卫星用电池难以满足需求,急需开发高能量高功率的锂离子电池。采用兼具容量和功率性能的镍钴铝酸锂(LiNixCoyMnzO2, NCA)作为正极活性材料,高容量中间相炭微球(MCMB)作为负极活性材料,显著提升了电池体系的容量和比能量。通过设计极片的活性物质载量和电解液用量,保证了电池功率性能(≥10 C)的发挥;通过加大电极片面积和极柱尺寸,控制了大倍率放电时电池温升。研制了兼顾高比能和高功率的锂离子电池单体,额定容量20 Ah,1 C放电比能量达到180 Wh.kg^-1,且10 C放电容量相较1 C保持率96.24%,15 C下持续放电比功率超过2 000 W.kg^-1,可以满足下一代轻小型SAR卫星能源供电需求。     

企业技术创新的内外源双驱动力因素

企业技术创新活动是一个复杂的过程,受来自企业内外部多种因素的综合作用影响。研究技术创新的内外源动力因素,对于解决企业技术创新过程中的制约要素与推动技术创新活动的顺利进行,不仅有理论上的价值,还具有重要的现实意义。     

动力系统试验台充气系统优化设计

某试验台承担了多项运载火箭动力系统的试验任务,试验前需要对箭上气瓶进行充气.由于箭上所带气瓶个数较多,充气压力较高,充气所需时间较长,操作人员工作量较大.同时,满足总体单位充气速率要求的难度较大.为了解决以上难题,借助AMESim软件对地面工艺系统进行仿真,获得箭上气瓶充气流量及地面气源压力的变化情况.根据仿真结果进行优化设计,通过在试验系统上增设孔板和增加数显二次仪表等针对性措施,实现了箭上气瓶充气速率在线调节的功能.对气瓶充气流程进行优化,充气气源采取高、低压切换逐瓶供应的方式.经动力系统试验考核,验证了系统优化设计的有效性.     

A New Probabilistic Transformation in Generalized Power Space

The mapping from the belief to the probability domain is a controversial issue, whose original purpose is to make (hard) decision, but for contrariwise to erroneous widespread idea/claim, this is not the only interest for using such mappings nowadays. Actually the probabilistic transformations of belief mass assignments are very useful in modern multitarget multisensor tracking systems where one deals with soft decisions, especially when precise belief structures are not always available due to the existence of uncertainty in human being's subjective judgments. Therefore, a new probabilistic transformation of interval-valued belief structure is put forward in the generalized power space, in order to build a subjective probability measure from any basic belief assignment defined on any model of the frame of discernment. Several examples are given to show how the new transformation works and we compare it to the main existing transformations proposed in the literature so far. Results are provided to illustrate the rationality and efficiency of this new proposed method making the decision problem simpler.     

The impact of microwave absorber and radome geometries on GNSS measurements of station coordinates and atmospheric water vapour

We have used microwave absorbing material in different geometries around ground-based Global Navigation Satellite System (GNSS) antennas in order to mitigate multipath effects on the estimates of station coordinates and atmospheric water vapour. The influence of a hemispheric radome – of the same type as in the Swedish GPS network SWEPOS – was also investigated. Two GNSS stations at the Onsala Space Observatory were used forming a 12 m baseline. GPS data from October 2008 to November 2009 were analyzed by the GIPSY/OASIS II software using the Precise Point Positioning (PPP) processing strategy for five different elevation cutoff angles from 5° to 25°. We found that the use of the absorbing material decreases the offset in the estimated vertical component of the baseline from ∼27 mm to ∼4 mm when the elevation cutoff angle varies from 5° to 20°. The horizontal components are much less affected. The corresponding offset in the estimates of the atmospheric Integrated Water Vapour (IWV) decreases from ∼1.6 kg/m² to ∼0.3 kg/m². Changes less than 5 mm in the offsets in the vertical component of the baseline are seen for all five elevation cutoff angle solutions when the antenna was covered by a hemispheric radome. Using the radome affects the IWV estimates less than 0.4 kg/m² for all different solutions. IWV comparisons between a Water Vapour Radiometer (WVR) and the GPS data give consistent results.     

机载大功率超导发电机发展现状与展望

新一代飞机对电力的需求越来越大,尤其是定向能武器的使用,将需要兆瓦(MW)级的电源系统。由于超导发电机发电功率大、结构简单、重量轻,是机载大功率用电设备的理想电源。本文综述了机载超导发电机的类型、研究进展和关键技术,分析指出了其未来的发展前景。