新型固态电压标准的研制

介绍了低成本、高稳定的固态电压标准器的研制 ,该标准器可取代 0 .0 0 0 5级以下的标准电池 ,具有较高的应用和推广价值。     

管制战术核心系统信息整合的实践与思考

日益增长的空中流量，对管制信息系统的信息整合提出了更高的要求。本文总结了成都管制中心的数据整合实践经验，提出整合管制信息系统的思路和建议，为未来的项目建设提供有意义的参考。     

美国空间态势感知系统发展现状及趋势分析

空间态势感知(SSA)是航天电子对抗的重点内容之一,SSA项目的研发已引起极大的关注.简要介绍了美国<2020年空军条令>中有关SSA的规划,重点讨论美国在研的几种SSA系统现状,明确了其未来的SSA是响应型.最后,分析了未来的响应型SSA.     

Cf / E 预浸料先进拉挤固化工艺

为探索与预浸料先进拉挤成型技术相适应的工艺方案,采用DSC研究了碳纤维/环氧预浸料USN12500的固化放热过程,对USN 12500的典型固化工艺进行改进,以此为基础设计了不同压力和加压时机下的试验方案,采用实验室现有设备模拟先进拉挤过程制备了试样,以制品的孔隙率作为考察指标优选了的拉挤成型固化的工艺参数.结果表明:制品在110℃下处理20 min,热压阶段130℃下处理15 min同时保持0.4MPa的工艺压力,后固化150℃下处理1.5h为工艺试验的优化方案,并且能够制得孔隙率＜1.1％的制品.     

开放式二氧化碳制冷性能

二氧化碳属于对环境友好的自然制冷工质,使用时直接排放对环境影响很小。本文提出一种开放式二氧化碳制冷系统,研究了高压二氧化碳在25,30和35°C三种典型储存环境下的制冷特性,同时考察了影响开放式二氧化碳制冷性能的各种因素。研究结果表明:二氧化碳储存状态对其制冷性能影响较大,在超临界条件下制冷量损失较大,同时,纯气体节流时储罐中的制冷量损失要远大于气液两相节流,为二氧化碳开放式制冷的应用提供了实验依据。     

冷变形TiNi合金的显微组织及超弹性

利用透射电镜观察不同温度下的拉伸试验，研究了冷变形量２２％的Ｔｉ－４９．８％Ｎｉ（原子分数）合金的显微组织及线性超弹性行为。透射电镜观察发现，Ｔｉ－４９．８％Ｎｉ（原子分数）合金经较大冷变形量变形后，其显微组织为细小片状且高度形变的马氏体。研究表明，冷变形Ｔｉ－４９．８％Ｎｉ（原子分数）合金经一定次数应力－应变循环处理后可获得完全的线性超弹性，出现线性超弹性的温度区间与冷变形ＴｉＮｉ合金的Ａｓ点有     

Rayleigh问题的Monte Carlo直接模拟

利用流场直接模拟的Ｍｏｎｔｅ Ｃａｒｌｏ方法数值模拟了Ｒａｙｌｅｉｇｈ问题的流场，获得了相应的结果，结果与解析解及经验解吻合较好，ＤＳＭＣ方法避免了求解复杂的控制方程，在流动比较复杂的情形下，有很大的优越性，是研究稀薄气体流动的一种好方法。     

Extension of the low diffusion particle method for near-continuum two-phase flow simulations

The low diffusion (LD) particle method, proposed by Burt and Boyd, is modified for the near-continuum two-phase flow simulations. The LD method has the advantages of easily coupling with the direct simulation Monte Carlo (DSMC) method for multi-scale flow simulations and dramatically reducing the numerical diffusion error and statistical scatter of the equilibrium particle methods. Liquidor solid-phase particles are introduced in the LD method. Their velocity and temperature updating are respectively, calculated from the motion equation and the temperature equation according to the local gas properties. Coupling effects from condensed phase to gas phase are modeled as momentum and energy sources, which are respectively, equal to the negative values of the total momentum and energy increase in liquid or solid phase. The modified method is compared with theoretical results for unsteady flows, and good agreements are obtained to indicate the reliability of the one-way gas-to-particle coupling models. Hybrid LD-DSMC algorithm is implemented and performed for nozzle discharging gas-liquid flow to show the prospect of the LD-DSMC scheme for multi-scale two-phase flow simulations.     

Adaptive double-saturated control for hovering over an asteroid

Hovering over an irregular-shaped asteroid is particularly challenging due to the large gravitational uncertainties and various external disturbances. An adaptive control scheme considering commanded acceleration and its change-rate saturation for hovering is developed in this paper. Taking full advantage of terminal sliding-mode control theory, first, we convert the double-saturated control problem to a new equivalent system by introducing a special bounded function, in which just control input saturation needs to be considered. Then, a continuous finite-time saturated controller is designed for the new system with the assistance of an constructed auxiliary subsystem. Additionally, an adaptive law is devised for the controller to avoid the requirement of the unknown upper bounds of the disturbances, rendering the control scheme especially suitable to asteroid hovering missions. The finite-time stability of the whole closed-loop system is proved via Lyapunov analysis. Numerical simulation studies are carried out, and the results demonstrate the design features and the desired performance.