液氧/煤油发动机换热器试车台配气系统设计

在液氧/煤油发动机研制试验过程中,需要对发动机的换热器进行试验验证,以此来满足发动机对换热器的要求。主要阐述了利用音速孔板控制以及计算气体流量的具体方法、理论计算,以及使用过程中所存在的问题和解决的方法。所设计的配气系统满足了液氧/煤油发动机换热器系统的试验要求。     

一种无人机高度传感器信息融合方法

在无人机(UAV)飞行控制系统(FCS)中,针对单一高度传感器测量精度有限,难以满足高精度高度定位需求的问题,提出一种信息融合方法。为了提高定位精度,在机上安装多个传感器测量高度,根据飞行控制系统高度状态方程,充分利用各传感器的测量信息,采用Kalman滤波技术,估计真实高度和大气数据计算机(ADC)的测量偏差,从而进行修正。仿真表明,所得结果的精度高于任何单一传感器的测量精度。因此,该方法有效地提高了系统高度信息获取的准确度。     

考虑超售的多级运价航空货运容量分配模型

舱位控制在航空收益管理中处于核心地位，目前已有的研究成果主要集中于航空客运方面，而对航空货运舱位控制方面的研究比较少。航空公司要提高货运收益，应和客运一样尽量将货舱提供给运价高的货物，但由于各个等级舱位请求到达时间不同，从而如何控制各个阶段的舱位销售数量以及合适的超售水平成为影响航空公司货运收益的关键。基于此，基于收益管理的思想，采用动态规划方法建立了考虑超售时的多级运价体系下航空货运舱位分配模型，由该模型得出航空货运舱住动态优化控制的策略，从而试图为航空公司实现每阶段货运销售的卖时控制提供方法和管理建议。     

WHAT DRIVES BUSINESS AND LEISURE AIR PASSENGER TRANSPORT DEMAND

The back-propagation neural network ( BPN ) is used to explore what the most influential variables are to drive business and leisure air passenger travel from Japan to Taiwan.The variables are systematically identified , evaluated and analyzed in detail.The results reveal that some factors affect both leisure and business air passenger transport , and the others only affect one of them.Flights from Tokyo to Taipei and average hotel rate in Taiwan are the two most important factors for forecasting the demand of leisure air passenger transport , while variables related to business activities have more effect on the demand forecast of business air passenger transport.By using BPN , a forecasting model that considers actual market segments is established , and the results show that it is an accurate tool to forecast air transport demand.     

Ignition enhancement of ethylene/air by NOx addition

Recently, non-equilibrium plasma assisted combustion (PAC) has been found to be promising in reducing the ignition delay time in hypersonic propulsion system. NO x produced by non-equilibrium plasma can react with intermediates during the fuel oxidation process and thereby has influence on the combustion process. In this study, the effects of NO x addition on the ignition process of both the homogeneous ethylene/air mixtures and the non-premixed diffusion layer are examined numerically. The detailed chemistry for ethylene oxidization together with the NO x sub-mechanism is included in the simulation. Reaction path analysis and sensitivity analysis are conducted to give a mechanistic interpretation for the ignition enhancement by NO x addition. It is found that for both the homogenous and non-premixed ignition processes at normal and elevated pressures, NO 2 addition has little influence on the ignition delay time while NO addition can significantly promote the ignition process. The ignition enhancement is found to be caused by the promotion in hydroxyl radical production which quickly oxidizes ethylene. The promotion in hydroxyl radical production by NO addition is achieved in two ways:one is the direct production of OH through the reaction HO2+NO = NO2+OH, and the other is the indirect production of OH through the reactions NO+O2=NO2+O and C2H4+O = C2H3+OH. Moreover, it is found that similar to the homogeneous ignition process, the acceleration of the diffusion layer ignition is also controlled by the reaction HO2+NO = NO2+OH.     

Physics results with the ARGO-YBJ experiment

ARGO-YBJ is a multipurpose experiment consisting in a dense sampling air shower array with 93% sensitive area located at very high altitude. The apparatus is in stable data taking since November 2007 at the YangBaJing Cosmic Ray Laboratory (Tibet, PR China, 4300 m a.s.l., 606 g/cm²). In this paper we report the main results in Gamma-Ray Astronomy and Cosmic Ray Physics after about 3 years of operation.     

No direct correlation between galactic cosmic rays and earth surface temperature

We have searched for a correlation between galactic cosmic rays (GCRs) and global earth surface air temperature (GST) datasets going back to the year 1900. The linear correlation coefficient between GCRs and GST varies erratically, exhibiting both positive and negative values over time scales varying from about 5–20 years. Since the finding of no persistent correlation is not supported by predictive theory but is what one should expect for two random, un-correlated time series, we infer that GCRs do not influence global surface air temperature.     

基于灰色马尔可夫链的航空货邮预测

结合航空货邮的特点和灰色预测及马尔可夫链理论的优点，提出航空货邮预测的灰色马尔可夫链模型。灰色马尔可夫链模型既考虑了从时间序列中挖掘数据的演变规律，又通过状态转移概率矩阵的变换，考虑数据的随机波动，它将时问序列数据固有的两种性质有机结合起来，具有严密的科学性，能较好地应用于中国航空货邮运输量的预测。     

自主近距空战中机动动作库及其综合控制系统

针对自主近距空战中机动动作库的设计,采用定性与定量结合的方法对机动动作进行描述,以准确体现机动动作的几何形态和战术意义,构成含描述参数的机动动作库。对于机动动作的控制,提出了按照任务控制-运动学控制-动力学控制-被控对象划分的综合控制系统多层递阶结构。其中,机动动作控制器针对每种机动动作分别设计指令生成器,生成气流角和速率指令;气流角控制器采用含指令滤波的backstepping方法进行控制律设计。以半滚倒转和高速摇摇为例进行仿真验证,仿真结果表明,机动动作的描述参数能准确体现其几何形态和战术意义,并通过综合控制系统实现有效控制。     

基于复杂网络的空中交通特征与延误传播分析

空中交通流量管理主要集中在尾随间隔、空中等待等局部战术空中交通流量调配,对空中交通流量整体运行规律、延误传播和整体解决的研究较少。航空运输网络是一个复杂系统,从复杂网络理论角度对航空运输网络进行研究很有必要。首先,分析了空中交通流量网络的度、度分布、权值、权分布、流量、容量、延误等静态特征;然后,提出了空中交通流量网络整体效能评估方法,使用选择性攻击和随机攻击方法分析了空中交通流量网络的抗毁性,基于负荷容量级联失效模型和病毒传播模型与空中交通延误传播的相似性建立了空中交通延误传播模型,最后,使用实际运行数据验证了空中交通流量网络的特征与延误传播模型的有效性,该研究可以为大范围空中流量管理提供决策支持。