解决数据专线路由器的2000年问题

引言在 Cisco路由器风靡网络世界的今天 ,一种并不为多数人所熟悉的路由器——TELEBIT的 Net Blazer PN已伴随中国数字地震台网 ( CDSN)的海拉尔、白家疃两条实时地震数据专线 ,默默地走过了 5个年头。 5年来 ,随着对这种设备应用的不断深入 ,其诸多优越性日渐充分地显示出来。     

白家疃地区地热观测分析

介绍了白家疃地区的水文地质概况。利用二阶差分法处理了白家疃地震台地热观测井7年的地热观测资料，在时间域中提取出较为可信的地震前兆信息。探讨了地热异常变化对地震发生的影响。     

LCR—G型重力仪固体潮观测记录分析

对 LaCoste-Romberg G147加反馈系统重力仪在白家疃地震台进行的台站固体潮记录作调和分析,通过与其它型号重力仪观测资料对比。发现 LaCoste-Romberg G147重力仪台站固体潮观测的结果优于 GS15重力仪,并与 GEO 重力仪观测精度在同一个量级,因此得出白家疃地震台的潮汐因子。     

白家疃地震台地球物理观测室的建设

1 前言台站观测是地球物理和地震科学研究的基础.1957年以来,白家疃地震台积累了大量连续、完整、可靠的地磁、地震数据,为我国的地球物理和地震科学的研究工作,提供了宝贵资料,今后仍将发挥其应有的作用.60年代以来,地震仪的放大倍数迅速提高,同时,地震预报和国际资料交换任务也要求台站提高监测能力和观测精度.1974年5月,白家疃台开始承担国际资料交换任务,但由于     

我国地磁测量实用标准的建立与国际比测

本文概略介绍了我国地磁台站工作发展情况。详细介绍了建立我国地磁测量实用标准的过程,以及用国际地磁学与高空物理协会的台站仪器委员会所设地磁标准比较长设服务部提供的一组(三只)石英丝水平磁强计,在国家地震局地球物理研究所白家疃台比测的结果。它验证了我们所建的实用标准已达到了国际比测的精度要求,并为上述国际机构所肯定。     

太阳活动,磁暴与震前大气电场异常关系研究

通过对太阳活动,磁暴与大气电场异常关系的研究及１９９７年９月至１９９８年８月白家疃台大气电场和磁暴实际观测结果的分析,论述了震前观测到的大气电场负异常现象与太阳活动和磁暴现象无明显相关。     

新一代中国数字地震台网台站系统

以白家疃数字地震台为例，介绍了新一代中国数字地震台网台站系统的各种硬件单元及它们的相互联系与特征，同时介绍了系统的频率响应，数据流和动态范围，并与中国数字地震台网一期设备进行了简单比较。     

斩波稳零多路转换器的设计

多路转换器是地震数据采集系统重要组成部分,它位于形成滤波器和浮点增益放大器之间,其性能如何对系统的各项技术指标都有很大影响;因为BSO(Baisil Seismic Observation)系统要求动态范围大,精度高及零点漂移小等特点,给多路转换器的设计提出了更高的要求,为此,我们设计出了斩波稳零多路转换器。实践证明,在白家疃地震台几年的实记中是可靠的,达到了设计要求。     

北京基准地震台简介

一、环境北京基准地震台即白家疃地震台是国家地震局的第一类基本台。它位于北京西北郊颐温公路白家疃村南,京西九龙山——香峪大梁向斜北翼山前倾斜平原上。台基为洪积层,奥陶系灰岩埋藏于54米以下,上部为沙土层、沙砾层和卵砾层所覆盖,地下水位在15—20米左右。台内南部是地磁观测区,建有地磁绝对观测室、7米深的相对观测地下室、地磁实验室、地磁传输观测室和三个地磁比测观测亭,     

纪念顾功叙先生百年诞辰座谈会在京举办

2008年6月25日, 由中国地震局地球物理研究所、中国地震学会、中国地球物理学会联合举办的"纪念顾功叙先生百年诞辰座谈会" 在北京国家地球观象台(原白家疃地震台)召开.     

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Distribution of throughfall and stemflow in multi‐strata agroforestry,perennial monoculture,fallow and primary forest in central Amazonia,Brazil

The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.