Estimating surface evapotranspiration using combined MODIS and CBERS-02 data

Land surface evapotranspiration is one of the most important components in water cycle between earth and atmosphere, and plays a very important role in the atmosphere, hydrosphere, and biosphere of the planet. It is an urgent task to understand the evapotranspiration process over different surface types and conditions in agriculture, hydrogeology, forest, and ecology for the purpose of using water resources properly. Additionally, land surface evapotranspiration is a key parameter in the synop…     

叶绿素荧光量子产量的MODIS遥感算法

从荧光量子产量的原理出发,利用 MODIS 卫星数据建立了一种估算量子产量的算法--φ算法.通过 2006 年 3 月 23 日渤海和北黄海的 MODIS 数据计算了荧光量子产量,并与叶绿素荧光效率(cFE)产品进行了比较.结果表明,φ算法是一种更精确的荧光量子产量的估算算法,它有效地避免了 CFE 存在的几个误差来源:包括未考虑浮游植物的"包裹效应"、使用 412nm 的离水辐亮度反演的浮游植物吸收系数以及积分深度过浅.CFE在大部分海域出现负值,还出现了某些高估点;在有效数据范围内,两者存在明显的线性相关关系.φ算法估算的量子产量最高值在0.05左右,这与其它海区测量的值域范围基本一致.除辽东湾东北部和部分近岸水域外,大部分离岸水域在0.001～0.02的范围内.通过对φ算法的误差来源分析,认为发展一种新的反演 678nm 比吸收系数和平均吸收系数的波段比值算法是可行的,也是改进φ算法精度的有效方法.     

Scheduling Constraints and Interference Graph Properties for Graph-based Interference Coordination in Cellular OFDMA Networks

The currently emerging 802.16e (WiMAX) and 3GPP Long Term Evolution (LTE) cellular systems are based on Orthogonal Frequency Division Multiple Access (OFDMA). OFDMA suffers from heavy inter-cell interference if neighboring base stations use the same frequency range. One approach to solve this issue is the application of beamforming antennas in combination with interference coordination (IFCO) mechanisms between base stations. In this paper, we trace the problem of IFCO back to the graph coloring problem and investigate the achievable resource utilization of the interference coordinated system. We develop a heuristic that allows the combination of arbitrary scheduling algorithms with the IFCO mechanism. This allows an efficient utilization of the radio system’s frequency resources while still obeying scheduling constraints, such as Quality of Service requirements. Finally, we study the tradeoff between fairness and the total system throughput.

HSOPA关键技术的研究

介绍了即将被商用的HSDPA(高速下行分局接入技术)的演进技术——HSOPA(高速OFDM分组接入技术)、HSOPA技术特点及HSOPA的关键技术,并展望了HSOPA技术向后3G及4G的过渡情况。     

3GPP SA第50次会议报告

3GPPSA第50次会议于2010年12月12-16日在土耳其伊斯坦布尔召开.本文介绍了SA第50次全会的会议概况,以及各工作组的会议情况,重点介绍了3GPPSA当前讨论的热点问题,如机器类型通信,中继节点的安全问题等.     

Downlink Dimensioning for the HSDPA Standard

We present an analytic derivation of downlink dimensioning for a wireless network employing the High Speed Downlink Packet Access (HSDPA) standard [Moulsley, Conference Publication No. 477, IEE 2001], currently being developed by the 3rd Generation Partnership Project (3GPP) [http://www.3gpp.org] as part of the next stage in the evolution of the WCDMA standard. We determine the maximum possible cell radius such that the probability of outage, P_out, at the cells worst location does not exceed a preset value under full load condition. The results of the paper are presented in the form of curves obtained by numerical integration of integral expressions. The results can be used, for instance, to find the increase in cell radius achievable by a certain reduction in the threshold value of the Signal to Interference plus Noise Ratio (SINR) defining outage.Parts of this work were presented at the 2002 IEEE Wireless Personal Multimedia Communications conference (WPMC), Hawaii.Dan Avidor was born in Tel Aviv, Israel, on October 18, 1936. He received the B.Sc. degree in electrical engineering from the Technion-Israel Institute of Technology, Haifa, Israel, in 1958 and the M.Sc. and Ph.D. degrees in engineering from the University of California, Los Angeles, (UCLA) in 1970 and 1981, respectively. After completing his studies for the Ph.D. degree, he returned to Israel, where he served as a Research and Development Department Head in the Israeli defense forces. He is currently a Distinguished Member of Technical Staff in the Wireless Research Laboratory, Bell Labs, Lucent Technologies, NJ, USA. His current research interests are in adaptive arrays, signal processing, and simulation techniques for wireless systems.Sayandev Mukherjee (M92) was born in Bangalore, India in 1970. He received the Bachelor of Technology degree in electrical engineering from the Indian Institute of Technology, Kanpur, India, in 1991, and the M.S. and Ph.D. degrees in electrical engineering from Cornell University, Ithaca, NY, in 1994 and 1997, respectively. Since 1996, he has been a Member of Technical Staff in the Wireless Research Laboratory, Bell Labs, Lucent Technologies, NJ, USA. His research interests include stochastic models, wireless system simulations, and intelligent resource allocation in wireless systems.     

3G时代中国联通LBS业务发展模式探讨

3G时代LBS业务得到迅猛发展,由此对电信运营商带来了压力和挑战。本文在研究当前移动互联网LBS业务发展趋势的基础上,结合中国联通"电话导航"业务现状,提出了中国联通基于"电话导航"平台的LBS业务发展模式初步设想。     

HJ-1A NDVI与MODIS NDVI时间序列提取植被物候特征对比研究

以HJ-1A和MODIS为数据源,通过动态阈值法提取物候特征参数,对HJ-1A NDVI和MODIS NDVI时间序列进行植被物候特征提取进行定性和定量比较,通过比较结果,提出HJ-1A NDVI数据在该应用中存在的问题,促进国产中空间高时间分辨率影像数据在植被物候信息提取研究中的应用,提高其在生态系统研究中的应用价值。结果表明:在SOS、EOS和LOS以及TOMS几个主要的物候时间点上,MODIS NDVI时间序列的标准差较小,所得物候数据更为集中,偏离度较小,所得物候数据较稳定;而HJ-1A NDVI时间序列所得物候数据的标准差较大,数据偏离程度较大,而在POS、BOS和AOS等表征植被生命周期中生长幅度数据上,其标准差较小,离散程度小。     

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针对国内外尚无对霾的遥感监测,霾在NASA的MODIS产品中作为薄云处理的情况,基于MODIS数据,采用.NET分布式架构,结合MatlabCOM, ArcEngine等组件,建立一个区域霾监测系统,论述系统的设计思想及改进的霾反演算法,对华北地区部分霾天进行监测,结果显示该系统能够准确地模拟大气污染状况。     

基于MODIS数据的海表温度反演

海表温度（sea surface temperature , SST）对海洋科学的研究具有重要意义。通过卫星遥感反演是获得SST数据的方法之一。基于C#和IDL语言构建针对EOS/MODIS数据的海表温度反演软件,讨论软件的功能,同时给出具体的反演处理过程。最后以我国南海海域为例,将软件反演结果与实测数据对比。结果显示,反演结果与实测数据的线性相关系数约为0.91,标准误差约为0.7°C。反演结果以期对海洋开发探测提供参考。