ExoMars 2016火星探测计划进入、减速、着陆的验证任务分析

对欧洲航天局(ESA)火星探测的ExoMars 2016计划进行了概述,着重分析了进入、减速、着陆验证任务的关键环节,详细分析了进入、减速、着陆验证的任务组成、任务目标、任务规划以及相关关键技术等。结合我国火星探测目前的技术状态,需要针对进入、减速、着陆各关键技术进行合理的规划,并适时开展相关的试验验证。首先完成整个火星探测进入、减速、着陆平台的验证与研制,再进一步开展深入的火星探测科学任务研究。文章所述内容和分析可为我国下一步开展火星等深空探测任务提供参考。     

Neural network modeling of flight control system

Modeling of angle tracking systems in the presence of actuator non-linearity such as angle, position and rate limits is a very significant and difficult task in the design and implementation of aircraft, target-tracking, and missile guided systems. A new recurrent neural network with time-delayed inputs and output feedback is used for the modeling of angle tracking systems, with emphasis on the neural network architecture, principles and algorithms. The neural network controller with modeling units for angle tracking is designed by using TMS320C25 processors. For time and size requirements, limited precision technology and look-up table technology are used in the design of the hardware and software systems. Given a set of input commands, the network is trained to control the system within the constraints imposed by actuators. The results show that the proposed networks are able to model the angle tracking system through learning without separate consideration of the non-linearity of actuators     

4H-SiC材料中刃型位错的仿真模拟研究

根据4H-SiC刃型位错的特点,在Castep软件中建立了6×6×1的刃型位错模型。基于第一性原理,利用Castep程序对刃型位错的相关性质进行了计算,并与完整晶格的模拟结果进行了对比。结果表明在引入刃型位错之后,4H-SiC材料的带隙变窄,在靠近导带底部态密度出现了一个新的峰值,这主要是由位错芯处的悬挂键在禁带中引入了一个缺陷能级所致。     

取样位置对FGH95盘形件蠕变性能的影响

采用分级加载法分析在593℃,1034MPa条件下试样取样位置对FGH95粉末盘形件蠕变性能的影响.结果表明,不同位置的蠕变性能与该位置在盘形件热处理时的固溶冷速密切相关,冷速快的位置的蠕变起始塑性变形和稳态蠕变速率低于冷速慢的位置.     

用于信道盲均衡的基于软判决导向的LS算法

本文提出两种改进的基于软判决导向的最小平方均衡法。一种采用横向结构，另一种采用格式结构。这两种均衡算法的判决误差形式不同于一般的判决误差形式，它们的表达式是一种更为复杂的连续函数形式。通过计算机仿真，我们发现，采用横向结构的这种改进算法无论对于最小相位还是非最小相位信道的均衡均有较好的性能，而采用格形结构的这种改进算法的性能在非最小相位信道下的性能反而不如传统的格形算法。     

n维简并理想费米气体的化学势和热容量

本文对能谱为ε＝ａｐ＾ｓ的ｎ维并理想费米气体作了统一讨论，给出了它的一级近似遇米能，有限浊度下的化学势、内能以及热容量的表达式。     

强化排热的空间热泵系统分析

针对航天器潜在的各种类型热泵系统进行定性分析研究。综合分析表明,Rankine热泵系统综合性能最佳,效率高(理论上仅次于Stirling热泵系统),传热系数大,比重量小,地面上有长期运行的经验,其缺点是含有运动部件;Stirling热泵理论热效率虽高,但其传热系数小,比重量大,运动部件多;喷射式热泵和吸附式热泵系统最显著的优点是无运动部件,可靠性高,易于集成封装,而且还可以回收利用高温废热,不消耗系统电能,缺点是性能系数低,比重量大,设备十分庞大;对于其他类型热泵系统,其问题更多。     

电火花加工放电位置检测的电测量法

介绍了应用于电火花加工放电点位置检测中的信号检测和电磁信号检测法 ,同时指出它们各自的特点。在实际应用中 ,应根据不同的加工要求来选取不同的检测方法 ,实现电火花加工的最优控制 ,从而达到最好的加工效果。     

Critical phenomenon,crisis and transition to spatiotemporal chaos in plasmas

In a driven/damped drift-wave system a steady wave induces nonlinear variation of the dispersion of a perturbation wave (PW). Competition between the nonlinear dispersion with self-nonlinearity of the PW results in rich wave dynamic behaviors. In particular, a steady wave at the negative tangency slope of a hysteresis becomes unstable due to a saddle instability. It is found that such saddle steady wave (SSW) plays an important role in the discontinuous transition from a spatially coherent state to spatiotemporal chaos (STC). The transition is caused by a crisis due to a collision of the PW attactor to an unstable orbit of the SSW. In the time evolution, it is a ‘pattern resonance’ of the realized wave with the virtual SSW that triggers the crisis. The transition also displays as a critical phenomenon in parameter space, which is related to the change in the symmetry property of the motion of master mode (k = 1) of the PW with respect to that of SSW. In the spatially coherent state the former is trapped by the SSW partial wave, while in the STC it can become free from the latter, its trajectory crosses two unstable orbits of the SSW frequently, causing very turbulent behavior. This revised version was published online in August 2006 with corrections to the Cover Date.     

从动态飞行获得极曲线及相关性研究

本文研究飞机极曲线试飞及其与风洞的相关性问题.主要通过动态飞行获得飞机极曲线(C_y≤0.3)的飞行数据.飞行条件:高度为3～12 km;M数为0.8,0.9,1.2,1.8.结果表明:动态飞行技术是可行的,飞行极曲线与风洞极曲线的相关性较好.