Investigation of national policy shifts to impact orbital debris environments

Low earth orbit has become increasingly congested as the satellite population has grown over the past few decades, making orbital debris a major concern for the operational stability of space assets. This congestion was highlighted by the collision of the Iridium 33 and Cosmos 2251 satellites in 2009. This paper addresses the current state of orbital debris regulation in the United States and asks what might be done through policy change to mitigate risks in the orbital debris environment. A brief discussion of the nature of orbital debris addresses the major contributing factors including size classes, locations of population concentrations, projected satellite populations, and current challenges presented in using post-mission active debris removal to mitigate orbital debris. An overview of the current orbital debris regulatory structure of the United States reveals the fragmented nature of having six regulating bodies providing varying levels of oversight to their markets. A closer look into the regulatory policy of these agencies shows that, while they all take direction from The U.S. Government Orbital Debris Mitigation Standard Practices, this policy is a guideline with no real penalty for non-compliance. Various policy solutions to the orbital debris problem are presented, ranging from a business as usual approach to a consolidated regulation system which would encourage spacecraft operator compliance. The positive aspects of these options are presented as themes that would comprise an effective policy shift towards successful LEO conservation. Potential economic and physical limitations to this policy approach are also addressed.     

空战攻防对策力学准则的推广

对空战攻防对策力学准则进行了推广研究。导出考虑导弹杀伤半径不为零时的“圆捕获”的界栅方程，该方程表明“点捕获”界栅方程是“圆捕获”界栅方程的特例，给出了捕获区，逃逸区和界栅几何图形，该图形描述了界栅与视线距，视线变化率，视线角速度之间的关系；分析了导弹杀伤半径，导弹和目标机动能力的差值对导弹和目标空战效果的影响。     

航天器系统设计的可靠性准则

在对大量航天器工程案例分析的基础上,提炼出10条航天器系统（总体）设计的可靠性准则。遵循这些设计准则,将有利于航天器从系统级避免许多故障,或者消除故障对系统的影响,在阐述每条准则时,列举了一个或数个案例。     

浅谈施工企业降低工程成本的有效控制

在目前我国建筑市场竞争激烈的背景下,对于一个建筑企业而言,取得项目施工权固然重要,但合理控制并降低施工成本,在保证施工质量前提下取得相应利润回报更为关键,应从施工前、施工过程中、竣工后三个环节加以有效控制.     

氢键在丁羟推进剂湿老化与干燥恢复中的作用规律

回顾了丁羟推进剂湿老化与干燥恢复机理研究状况;指出了水分对氢键结构的影响;讨论了干燥条件下吸湿后的推进剂内部水分运行规律;以120mm×25 mm×10 mm的长方体丁羟推进剂试样为研究对象,在多种温度和相对湿度(RH)条件下进行了湿老化试验;以30℃、RH= 100％条件下湿老化5d的长方体试样为研究对象,采用无水氯...     

基于互相关向量估计的自适应盲均衡算法

基于互相关估计的盲MMSE均衡算法以批处理方式估计信道输出向量和信道输入信号之间不同延时的互相关向量,得到MMSE均衡器系数。由于涉及到大型矩阵乘积,若在线实现,计算量较大。根据该算法对信道阶数过估计不敏感特性,推导出基于互相关向量估计的盲MMSE均衡的自适应实现算法。自适应算法将矩阵和矩阵相乘转换为矩阵和向量的相乘,大大减少了均衡系数更新计算量,计算量仅为O(K2)(K为矩阵维数)。仿真结果显示自适应算法的收敛性能远远优于目前存在的自适应算法。     

波音737CL飞机模拟式座舱压力控制系统部件预防性维修与控制

针对波音737CL飞机模拟式座舱压力控制系统部件老龄化问题,提出部件预防性维修措施．减少因部件内部元器件老化造成的重复性故障,供业内同行参考。     

完善我国通用航空法律法规体系的思考

适应通用航空迅猛发展的需要,我国通用航空法律法规体系已经初步形成.为了更好地保障和促进我国通用航空发展,应修改《民航法》,制定《通用航空产业发展条例》,修订《通用航空飞行管制条例》,对现有规章进行系统化的编撰,完善我国通用航空法律法规体系.     

考虑扰动的无人机集群协同态势感知一致性评估

无人机（UAV）集群协同态势感知（SA）一致性是无人机集群协同作战的关键，对一致性进行评估至关重要。针对态势感知过程中面临的强不确定性等问题，在一致性评估指标体系的基础上，提出了基于证据推理规则的态势感知一致性评估方法，将各类指标信息统一至置信结构，并充分考虑指标的权重与可靠度。采用扰动分析法对复杂战场环境进行模拟，提出考虑扰动的态势感知一致性评估方法，并对算法进行了总结。最后，通过仿真算例和对比研究验证了所提方法在不确定性表达、一致性评估和无人机集群的环境适应性研究等方面的有效性。