一种基于复数域网络编码的双层卫星通信系统

针对卫星通信网络吞吐量不足、可靠性不高的问题,提出一种基于复数域网络编码(Complex Field Network Coding,CFNC)的卫星通信方案。该方案在信号发送前对源信息作预编码处理,即在复数域上选取一个大小合适的参数化空时码与源信号相乘,编码后的信号与源信号在复数域上有着一一映射关系。对该方案的吞吐量和成对差错概率(Pairwise Error Probability,PEP)做了详尽的理论分析,结果表明,采用该编码方案的卫星通信系统在终端发射功率不变的情况下,吞吐量比路由模式提高了100%以上,比传统的CFNC方式至少可提高75%。该方案还可以扩展至更多的地面源节点,从而支持多用户网络通信。最后,仿真实验表明,在较高的信噪比下,PEP仿真值逼近于渐近值,验证了理论分析的正确性。     

火焰温度场测试中的传感器动态特性补偿

在进行爆温测试时,爆炸伴随的高温火焰具有变化快、温度高、测试环境恶劣等特点.针对这种特定的测温场合,运用火焰温度源法研究了热电偶传感器在火焰温度场中的动态响应特性.为了减小热电偶的动态测量误差,通过粒子群优化算法(PSO)建立了测试系统的动态补偿滤波器模型.实验表明,这种研究方法有效地改善了热电偶的动态测量误差,对通过爆温测试进行弹丸热毁伤评价有一定的参考价值.     

数列极限在实际中的应用

数列极限是一类重要的极限,在经济和数学领域中发挥着重要的作用。以举例的方式介绍数列极限在现实生活中的应用,包括几何中计算曲线所围图形的面积．求二次方程的数值解,购房按揭贷款分期还款问题,及连续复利问题。     

Reprocessing the MODIS Leaf Area Index products for land surface and climate modelling

Land surface and climate modelling requires continuous and consistent Leaf Area Index (LAI). High spatiotemporal resolution and long-time record data are more in demand nowadays and will continue to be in the future. MODIS LAI products meet these requirements to some degree. However, due to the presence of cloud and seasonal snow cover, the instrument problems and the uncertainties of retrieval algorithm, the current MODIS LAI products are spatially and temporally discontinuous and inconsistent, which limits their application in land surface and climate modelling. To improve the MODIS LAI products on a global scale, we considered the characteristics of the MODIS LAI data and made the best use of quality control (QC) information, and developed an integrated two-step method to derive the improved MODIS LAI products effectively and efficiently on a global scale. First, we used the modified temporal spatial filter (mTSF) method taking advantage of background values and QC information at each pixel to do a simple data assimilation for relatively low quality data. Then we applied the post processing-TIMESAT (A software package to analyze time-series of satellite sensor data) Savitzky-Golay (SG) filter to get the final result. We implemented the method to 10 years of the MODIS Collection 5 LAI data. In comparison with the LAI reference maps and the MODIS LAI data, our results showed that the improved MODIS LAI data are closer to the LAI reference maps in magnitude and also more continuous and consistent in both time-series and spatial domains. In addition, simple statistics were used to evaluate the differences between the MODIS LAI and the improved MODIS LAI.     

Firms’ involvement in Open Source projects: A trade-off between software structural quality and popularity

Open Source (OS) was born as a pragmatic alternative to the ideology of Free Software and it is now increasingly seen by companies as a new approach to developing and making business upon software. Whereas the role of firms is clear for commercial OS projects, it still needs investigation for projects based on communities. This paper analyses the impact of firms’ participation on popularity and internal software design quality for 643 SourceForge.net projects. Results show that firms’ involvement improves the ranking of OS projects, but, on the other hand, puts corporate constraints to OS developing practices, thus leading to lower structural software design quality.     

Adoption of Open Source Software: The role of social identification

While the benefits of incorporating Open Source Software (OSS) into personal and organizational systems have been widely touted, OSS must be adopted and used by end users before these benefits can be realized. Drawing on research in information systems and sociology, this study develops and evaluates an integrated model for the acceptance of OSS. In addition to the traditional technology adoption variables the findings stress the importance of social identification as a key driver of OSS adoption. The proposed model provides a useful decision support tool for assessing and proactively designing interventions targeted at successful OSS adoption and diffusion.     

一种面向微博用户的标签推荐方法

首先对国内微博平台的信息进行了综合分析,主要介绍了微博信息的定义,在错综复杂的微博信息中哪些信息比较重要,以及这些微博信息包含哪些详细的内容,是如何组织的。然后选取新浪微博平台作为研究对象,利用新浪微博API设计了爬虫程序,抽取用户信息;以用户的关注人数、粉丝数和发布的微博数为标准对用户信息进行了定量分析。最后根据分析结果,针对不同特征的用户群体提出了相应的标签推荐方法。     

一种面向微博用户的标签推荐方法

首先对国内微博平台的信息进行了综合分析,主要介绍了微博信息的定义,在错综复杂的微博信息中哪些信息比较重要,以及这些微博信息包含哪些详细的内容,是如何组织的。然后选取新浪微博平台作为研究对象,利用新浪微博API设计了爬虫程序,抽取用户信息;以用户的关注人数、粉丝数和发布的微博数为标准对用户信息进行了定量分析。最后根据分析结果,针对不同特征的用户群体提出了相应的标签推荐方法。     

光纤通道存储局域网(FC_SAN)管理系统的研究

从管理角度介绍了典型的光纤通道局域网（Ｆｉｂｒｅ Ｃｈａｎｎｅｌ Ｓｔｏｒａｇｅ Ａｒｅａ Ｎｅｔｗｏｒｋ,以下简称ＦＣ_ＳＡＮ）环境,并阐述了管理该环境所面临的问题。同时,提出了一种局域网（Ｓｔｏｒａｇｅ Ａｒｅａ Ｎｅｔｗｏｒｋ,以下简称ＳＡＮ）管理体系,该体系分为两层,分别提供面向对象的服务和与实体相关的服务。     

邮区中心局生产作业仿真系统研究

邮区中心局生产作业仿真系统使手工难以进行的庞大数据分类处理及汇总分析得以实现,可以为中心局的生产作业和邮运调度管理与决策提供大量准则可靠的的数据资料和决策依据;文章对仿真系统的目标需求、分析设计和系统功能进行了介绍。