低压模化对燃气轮机燃烧室工作特性影响的数值分析

为研究低压模化对于燃气轮机燃烧室工作特性的影响,采用ANSYS软件的FLUENT模块,对燃烧室在低压模化以及低压1/3尺寸模化条件下的燃气轮机燃烧室分别进行数值模拟研究,并与在全压条件下的燃烧室计算结果进行对比分析。计算结果表明:在低压模化条件下,燃烧室的流线形态与全压下基本相同;由于压力对于化学反应平衡的影响,在低压条件下燃烧室的壁温相比在全压下的平均降低70~100 K,其出口温度场指标比在全压下的更好;由于受燃烧室入口空气压力的影响,在低压条件下燃烧室的燃烧效率和流阻损失均比在全压下的低;另外,由燃烧室压力和尺寸的变化引起的燃烧室内温度分布变化,造成NO源分布的不同及燃烧室内NO的生成速率发生巨大变化,导致燃烧室NOx的排放水平不同,并验证了压力指数。其计算结果可为燃气轮机燃烧室的低压和常压模化试验提供参考。     

一种基于激光测距的自动化药房库存盘点方法设计

针对自动化药房储药柜的药品快速盘点问题,设计了一种将激光测距传感器固定安装在机械手上,通过激光测距技术计算药盒数量的方法.采用贝加莱控制系统作为执行机构,上位机软件采用C#作为开发平台,二者采用MODBUS协议通信进行实时信息.上位机采用等代价搜索法对盘点储位进行路径优化,通过RS485通信获取激光测距返回数值来计算储药位药盒数量.实际运行结果表明,该系统可以实现自动化药房的快速盘点问题,并且可靠性高,大大降低了药房盘点的劳动强度.     

液体成型树脂基复合材料及其工艺研究进展

介绍了液体成型复合材料的主要类别和特点,论述了国内外液体成型树脂体系、液体成型树脂匹配的定型剂、液体成型复合材料预成型体制备工艺等技术进展.介绍了近年来液体成型复合材料发展迅速或备受关注的新工艺,如高压RTM成型工艺、热塑性树脂基液体成型工艺、自动铺放液体成型工艺、SQRTM成型工艺等.展望了液体成型复合材料未来发展趋...     

采用PQLF的不确定模糊系统最优保性能控制

对一类模有界的参数不确定T-S模糊系统的保性能控制问题进行了分析研究。一个二次指标函数表征了闭环系统的性能。采用分段二次Lyapunov函数(Piecewise quadratic Lyapunov function,PQLF)方法,在使闭环系统渐近稳定的前提下以线性矩阵不等式(Linear matrix inequality,LMI)的形式给出了一种鲁棒最优保性能控制律。同时提出了一种新型分段并行补偿(Parallel distributed compensation,PDC)控制策略。该PDC控制器同样反映了模糊系统前提变量的规则结构信息。数值仿真显示,采用该设计方法所得到的闭环保性能值优于传统二次Lyapunov函数(Common quadratic Lyapunov function,CQLF)方法下的闭环保性能值,且系统动态性能良好,鲁棒性强。     

基于传递闭包法的航班分类模型及在航班排序中的应用

提出了一种基于传递闭包法的进/离场航班分类方法.首先对模糊集合理论和传递闭包算法作了简要的介绍,然后在考虑4种不同因素的条件下建立了航班分类模型,并给出了各类航班单位时间延误成本的计算公式.最后以终端区航班排序模型为例,对该方法进行了仿真,并与传统航班延误成本分类方法进行了比较.仿真结果表明,该方法有助于减少航班延误损失,优化进/离场航班队列,提高空中交通管理效率.     

Towards the automated operations of large distributed satellite systems. Part 2: Classifications and tools

Recent developments have seen a trend towards larger constellations of spacecraft, with some proposals featuring constellations of more than 10.000 satellites. While similar concepts for large constellations already existed in the past, traditional satellite deployments hardly ever feature groups of more than 100 satellites. This trend towards considerably larger satellite numbers originates from non-traditional design and operations of spacecraft by non-traditional space companies. The evolution in the space sector, precipitated by new players, is often referred to as “Space 4.0” or “New Space”. It necessitates a rethinking of the way satellites and satellite constellations are planned, designed, and operated. New operational paradigms are needed to enable automatic, optimal task definition, and scheduling in a holistic approach.This is the second of two companion papers that investigate the operations of distributed satellite systems. This second article investigates the classification of distributed satellite systems and evaluates commercial tools for automated spacecraft operations, whereas the first article performed a survey of conventional and “new space”operations of spacecraft constellations.Classification metrics for constellations are derived and evaluated with respect to their informative value concerning the operation, the automation, and the scalability of the constellation. The proposed classification system is applied to the Dove and RapidEye constellation and allows for a comparison between the presented automation approaches. Commercial tools for automated spacecraft operations are evaluated for several mission task elements, such as orbit control, orbit maintenance, and collision avoidance. Subsequently, the trends, benefits, and standardization needs for operational automation are identified.     

Development cost prediction of general aviation aircraft projects with parametric modeling

The study of the development cost of general aviation aircraft is limited by small samples with many cost-driven factors. This paper investigates a parametric modeling method for prediction of the development cost of general aviation aircraft. The proposed technique depends on some principal components, acquired by utilizing P value analysis and gray correlation analysis. According to these principal components, the corresponding linear regression and BP neural network models are established respectively. The feasibility and accuracy of the P value analysis are verified by comparing results of model fitting and prediction. A sensitivity analysis related to model precision and suitability is discussed in detail. Results obtained in this study show that the proposed method not only has a certain degree of versatility, but also provides a preliminary prediction of the development cost of general aviation aircraft.     

浅析DRM数字调幅广播技术与应用

本文介绍了DRM数字调幅广播的系统结构、与传统模拟广播相比的技术优势,以及DRM在传统模拟广播单一语音业务以外的应用.     

飞机排班系统在航空公司生产运行领域中的应用和探讨

宏观介绍了航空公司生产运行领域飞机排班系统的主要功能组成和使用情况及其与相关系统之间的关联关系，并结合航空公司的未来发展趋势，提出了系统建设方面的一些思路和设想，为生产运行系统的持续改进提供一定的借鉴和参考。     

产业结构调整中的社会成本问题研究

2010年是继续应对国际金融危机、保持经济平稳较快发展、加快转变经济发展方式的一年,站在全局角度进行战略性经济结构调整,不能过于盲目,还要顾及一些基本的社会问题,尤其是民生问题,尽量在保持社会平稳健康有序向前推进的目标下,保证经济发展有活力而且可持续。所以,应该重视三大社会成本:经济时滞成本、就业与教育成本、社会保障成本。文章正是出于以上考虑,核算由调整所引起的这三大社会成本,以便在制定政策抉择时能够做到有的放矢。