基于Volterra捕食模型的飞行流量动态调配

为缓解当前飞行流量需求与空域资源限制间的矛盾,改善静态流量分配方式下航路飞行流量限制问题,提出飞行流量动态调配概念并建立动态调配模型及算法.首先根据Volterra捕食模型的思想,以航路负荷值大小为依据划分种群,依据航路飞行流量的调配速度建立飞行流量的动态调配模型,然后提出实时流量动态调配算法,按时段周期性对航路的飞行流量重新划分种群,并根据航路当前状况对飞行流量进行动态调配.最后运用Matlab软件进行算例分析,结果表明了模型及算法的有效性,可以很好地应用于飞行流量的动态调配研究中.     

Application of SVM on satellite images to detect hotspots in Jharia coal field region of India

The present paper deals with the application of Support Vector Machine (SVM) and image analysis techniques on NOAA/AVHRR satellite image to detect hotspots on the Jharia coal field region of India. One of the major advantages of using these satellite data is that the data are free with very good temporal resolution; while, one drawback is that these have low spatial resolution (i.e., approximately 1.1 km at nadir). Therefore, it is important to do research by applying some efficient optimization techniques along with the image analysis techniques to rectify these drawbacks and use satellite images for efficient hotspot detection and monitoring. For this purpose, SVM and multi-threshold techniques are explored for hotspot detection. The multi-threshold algorithm is developed to remove the cloud coverage from the land coverage. This algorithm also highlights the hotspots or fire spots in the suspected regions. SVM has the advantage over multi-thresholding technique that it can learn patterns from the examples and therefore is used to optimize the performance by removing the false points which are highlighted in the threshold technique. Both approaches can be used separately or in combination depending on the size of the image. The RBF (Radial Basis Function) kernel is used in training of three sets of inputs: brightness temperature of channel 3, Normalized Difference Vegetation Index (NDVI) and Global Environment Monitoring Index (GEMI), respectively. This makes a classified image in the output that highlights the hotspot and non-hotspot pixels. The performance of the SVM is also compared with the performance obtained from the neural networks and SVM appears to detect hotspots more accurately (greater than 91% classification accuracy) with lesser false alarm rate. The results obtained are found to be in good agreement with the ground based observations of the hotspots. This type of work will be quite helpful in the near future to develop a hotspots monitoring system using these operational satellites data.     

飞机电气系统参数测试标准实施中问题分析

结合本标准宣贯、研讨会上所提供的信息,分析了飞机电气系统参数测试标准在实际应用中存在的一些问题,并对瞬态电压和频率调制率等重点问题进行了详细的讨论和分析.     

多机场地面等待问题模型研究

近几年世界民用航空事业的飞速发展 ,机场容量的限制引起了交通拥挤并造成了巨额损失 ,使得流量管理问题变得越来越迫切。文中针对多机场的地面等待问题 ,建立了一种行之有效的地面等待管理系统模型 ,并提出了忽略航路交叉点容量、空中延误为 0及起飞容量无限的简化模型。     

The effect of geocenter motion on Jason-2 orbits and the mean sea level

We compute a series of Jason-2 GPS and SLR/DORIS-based orbits using ITRF2005 and the std0905 standards ( Lemoine et al., 2010). Our GPS and SLR/DORIS orbit data sets span a period of 2 years from cycle 3 (July 2008) to cycle 74 (July 2010). We extract the Jason-2 orbit frame translational parameters per cycle by the means of a Helmert transformation between a set of reference orbits and a set of test orbits. We compare the annual terms of these time-series to the annual terms of two different geocenter motion models where biases and trends have been removed. Subsequently, we include the annual terms of the modeled geocenter motion as a degree-1 loading displacement correction to the GPS and SLR/DORIS tracking network of the POD process. Although the annual geocenter motion correction would reflect a stationary signal in time, under ideal conditions, the whole geocenter motion is a non-stationary process that includes secular trends. Our results suggest that our GSFC Jason-2 GPS-based orbits are closely tied to the center of mass (CM) of the Earth consistent with our current force modeling, whereas GSFC’s SLR/DORIS-based orbits are tied to the origin of ITRF2005, which is the center of figure (CF) for sub-secular scales. We quantify the GPS and SLR/DORIS orbit centering and how this impacts the orbit radial error over the globe, which is assimilated into mean sea level (MSL) error, from the omission of the annual term of the geocenter correction. We find that for the SLR/DORIS std0905 orbits, currently used by the oceanographic community, only the negligence of the annual term of the geocenter motion correction results in a – 4.67 ± 3.40 mm error in the Z-component of the orbit frame which creates 1.06 ± 2.66 mm of systematic error in the MSL estimates, mainly due to the uneven distribution of the oceans between the North and South hemisphere.     

SQL Server数据复制在自来水数据库系统中的实现

介绍了Microson SQL Server数据复制的概念、工作原理和拓扑结构,并结合自来水公司的业务特点和应用需求,提出了适合企业业务发展的分布式系统解决方案.     

不同型线结构船艏表面压力特性对比实验研究

为优选船艏结构型线方案,在风洞中针对三个在结构型线上仅有细微差别的船艏方案进行表面压力特性对比测试。实验获得了各型线方案模型表面压力空间分布特性和压力脉动特性,并通过表面压力特性的综合对比进行了结构型线评估,为船艏的结构型线设计提供直接的技术依据。     

高性能飞行器大气数据传感技术研究进展

大气数据是飞行器导航和控制的重要参数，大气数据传感技术是实现飞行器飞行安全及性能发挥的重要保障。针对高性能飞行器对大气数据传感技术的发展需求进行分析，重点介绍了传统大气数据传感技术、嵌入式大气数据传感技术、光学大气数据传感技术及虚拟大气数据传感技术的发展和特点，并对推动嵌入式大气数据传感技术发展的相关技术问题进行了分析和总结，最后对大气数据传感技术的发展进行展望。     

Hypothesis-test-based landcover change detection using multi-temporal satellite images – A comparative study

Remote sensing images and technologies have been widely applied to environmental monitoring, in particular landuse/landcover classification and change detection. However, the uncertainties involved in such applications have not been fully addressed. In this paper two hypothesis-test-based change detection methods, namely the bivariate joint distribution method and the conditional distribution method, are proposed to tackle the uncertainties in change detection by making decisions based on the desired level of significance. Both methods require a data set of class-dependent no-change pixels to form the basis for class-dependent hypothesis test. Using an exemplar study area in central Taiwan, performance of the proposed methods are shown to be significantly superior to two other commonly applied methods (the post-classification comparison and the image differencing methods) in terms of the overall change detection accuracies. The conditional distribution method takes into consideration the correlation between digital numbers of the pre- and post-images and the effect of the known pre-image digital number on the range of the post-image digital number, and therefore yields the highest change detection accuracy. It is also demonstrated that the class-dependent change detection is crucial for accurate landuse/landcover change detection.     

中间件技术的研究及应用

本文在分析了分布式应用系统体系结构发展变化的基础上．阐述了中间件的概念、功能和在可重用、多异构数据源应用系统的作用，对ODBC、BDE／IDAPIT、0LEDB／ADO和JDBC等分布式数据库中间件；CGI、lSAPI／NSAPI、ASP、JSP等中间件进行了分析比较，并给出了中间件技术在教务管理信息系统的应用实例。