Remote sensing estimates of boreal and temperate forest woody biomass: carbon pools, sources, and sinks

The relation between satellite measurements of the normalized difference vegetation index (NDVI), cumulated over the growing season, and inventory estimates of forest woody biomass carbon is estimated statistically with data from 167 provinces and states in six countries (Canada, Finland, Norway, Russia and the USA for a single time period and Sweden for two periods). Statistical tests indicate that the regression model can be used to represent the relation between forest biomass and NDVI across spatial, temporal and ecological scales for relatively long time scales. For the 1.42 billion ha of boreal and temperate forests in the Northern Hemisphere, the woody biomass carbon pools and sinks are estimated at a relatively high spatial resolution (8×8 km). We estimate the carbon pool to be 61±20 gigatons (10⁹) carbon (Gt C) during the late 1990s and the biomass sink to be 0.68±0.34 Gt C/year between the 1982 and 1999. The geographic detail of carbon sinks provided here can contribute to a potential monitoring program for greenhouse gas emission reduction commitments under the Kyoto Protocol.     

相干光源的研制现状

本文叙述了近年来国外相干光源的研究及其进展。并对频谱线宽、FM 调制特性和波长可变特性作了介绍。     

1.3μm high—power superluminescent diode

The result of the evaporation of Sio/SiO2 two layer antireflection coatings monitored by the MODEL IL 400 DEPOSITION CONTROLLER is re-ported.A superluminescent diode with high output power is fabricated by evaporate-ing antireflection coating on the front facet of 1.3цm buried heterostructure laser.     

国际基本安全标准的进展

本文主要阐述了由国际原子能机构等国际组织制定的“国际电离辐射防护和辐射源安全的基本安全标准”的主要特点。标准主要是基于国际放射防护委员会１９９０年建议书，但也考虑了国际核安全咨询组建议的原则。其内容不仅包括辐射防护，还包括辐射源的安全，在总结世界各国辐射防护和安全实践经验的基础上，在潜在照射、医学照射、废物管理、豁免值、事故应急、慢性照射、天然照射和医学防护等方面均提出了一些新的和具体的要求。我国有必要在仔细研究这一标准的基础上结合具体情况，修订现行标准。文中提出了在采用这一标准时需要研究的一些问题。     

S波段低相位噪声参考原

阐述了研制Ｓ波段低相噪参考源所需的晶振相噪特性、倍频器相噪特性，指出研制低相噪参考源的途径，在此基础上研制出了Ｓ波段极低相噪参考源，经严格测量，其相位噪声在１ｋＨｚ处优于－１２１ｄＢｃ／Ｈｚ，１００ｋＨｚ以外的相噪平底优于－１３５ｄＢｃ／Ｈｚ。所用２０次培频器几乎无附加相噪。     

入侵检测系统研究综述

首先论述了入侵检测系统(IDS)的研究概况,然后使用五种分类标准对入侵检测系统进行了科学分类,它们分别是控制策略、同步技术、信息源、分析方法和响应方式。接着,介绍了入侵检测系统的一些重要工具,并重点研究分析了基于信息源IDS和基于分析方法IDS,最后给出了入侵检测系统研究趋势和展望。     

我国企业CRM在电子商务环境下的应用探讨

中国正处在CRM发展的初级阶段,具有其发展的独特性,中国企业要在世界范围内激烈的竞争中争得一席之地,实施客户关系管理,提供个性化服务是大势所趋.本文在对电子商务环境下的CRM应用作了简要述评,指出了国内CRM应用情况的基本特点,重点剖析了应用中出现的难点问题,并对这些问题的解决提出了建议.     

信息准则在信息融合中的应用

在图像识别时,如果样本较小,往往会造成识别结果的不准确.采用信息融合的方法可以改善这一问题.在这一过程中,通过引入信任度系数对信息源的质量作出评价,可以提高图像识别的准确性.提出了一种利用信息准则来确定信息源信任度系数的方法,并以此作为衡量信息源质量的依据.其中着重比较了根据两种不同的信息准则所确定的信任度系数对于识别结果的影响.实验结果表明利用BIC准则确定的信任度系数可以得到更好的图像识别结果,同时也证明了该方法应用在信息融合中的可行性.     

中国化学电源50年(2)──中国电池发明专利

概括了自我国专利法实施以来有关化学电源的发明专利的进展。包括Zn/MnO2电池、可充碱锰电池、MH／Ni电池、Cd/Ni电池、锂电池和锂离子电池、铅酸电池等的材料、工艺、制造诸方面的概况。     

Mining spatio-temporal patterns in object mobility databases

With the increasing use of wireless communication devices and the ability to track people and objects cheaply and easily, the amount of spatio-temporal data is growing substantially. Many of these applications cannot easily locate the exact position of objects, but they can determine the region in which each object is contained. Furthermore, the regions are fixed and may vary greatly in size. Examples include mobile/cell phone networks, RFID tag readers and satellite tracking. This demands techniques to mine such data. These techniques must also correct for the bias produced by different sized regions. We provide a comprehensive definition of Spatio-Temporal Association Rules (STARs) that describe how objects move between regions over time. We also present other patterns that are useful for mobility data; stationary regions and high traffic regions. The latter consists of sources, sinks and thoroughfares. These patterns describe important temporal characteristics of regions and we show that they can be considered as special STARs. We define spatial support to effectively deal with the problem of different sized regions. We provide an efficient algorithm—STAR-Miner—to find these patterns by exploiting several pruning properties. Responsible editors: Charles Perng and Tao Li.