怀来地震台伸缩仪EW向改进试验

对怀来台伸缩仪EW向基线固定端、传感器进行布设改进试验,将原有28m长基线改为两段短基线（东段：14．6m,西段：13．4m）。改进后,两条短基线取得了较好的观测成果,其中东段基线改造效果非常明显,观测曲线干扰减少,光滑度显著提高,观测数据精度明显优于改造前的观测数据。这次改造试验解决了困扰怀来台多年的难题。     

短基线光纤应变仪的研制

<正>形变观测是地震前兆观测的重要手段,形变观测仪器的性能直接决定地震前兆观测资料的质量。传统的胴体长基线形变仪对安装环境要求高、工程造价高,抗环境干扰能力差。减小伸缩仪的基线长度,实现仪器的小型化有助于地震应急快速布设,开展多方位应变观测(例如,垂直分量),也可降低胴体开凿成本,并提高仪器的维护性。鉴于此,国内地震系统已经开始研制短基线/超短基线伸缩仪的研制。光纤地震     

一种短基线伸缩仪的设计与实现

SS-Y伸缩仪在中国地壳形变观测中已安装使用多年, 为了保证观测信噪比, 伸缩仪基线长度一般在10~30 m之间, 过长的基线导致仪器易受环境干扰的影响; 同时, 由于没有密封设计, 长期使用会出现格值误差等问题。针对SS-Y伸缩仪所存在的不足, 研制了一种新型短基线伸缩仪, 仪器基线长度为1 m, 采用具有较高精度的电容传感器进行位移测量, 并设计了全新的整体密封结构, 使仪器具备更好的抗干扰能力。线性度、 灵敏度等参数测试及观测试验结果表明, 该新型短基线伸缩仪具有良好的性能特性和观测信噪比, 这为仪器的进一步优化打下了基础。     

SS-Y型伸缩仪观测问题分析及优化方法探讨

SS-Y型伸缩仪在我国地震洞体形变监测台网中已安装使用多年.对地球固体潮观测而言,仪器观测资料精度高且长期稳定性较好,但从地震预测的观测需求来看,SS-Y型伸缩仪仍然存在很多不足,如高频信息缺失、抗干扰能力较弱、存在格值误差、自校验能力较差等.对伸缩仪存在的问题进行分析,并提出一种超宽频带短基线伸缩仪的设计思路,以期为后续新仪器的研制提供理论依据.     

SS-Y型伸缩仪观测问题分析及优化方法探讨

SS-Y型伸缩仪在我国地震洞体形变监测台网中已安装使用多年。对地球固体潮观测而言,仪器观测资料精度高且长期稳定性较好,但从地震预测的观测需求来看,SS-Y型伸缩仪仍然存在很多不足,如高频信息缺失、抗干扰能力较弱、存在格值误差、自校验能力较差等。对伸缩仪存在的问题进行分析,并提出一种超宽频带短基线伸缩仪的设计思路,以期为后续新仪器的研制提供理论依据。     

SS—Y型短基线伸缩仪及其标定装置

介绍了SS－Y型基线伸缩仪总体设计思想、整体结构和主要部件的工作原理及台站试验情况，试验表明，，由于使用含饴特种因瓦棒、（为基线）和高灵敏度的换能器、精度超微量标定平台以及有效的操作系统，在缩短基线的条件下，保持了高精度与高稳定性，在NS分量不大于6m, EW分量不大于10m的基线上，能记录到清晰的应变固体潮汐、其观测精度优于现有台站的观测水平，并彻底地解决了石英管炸裂、汞泄漏污染现象，同时，智能化记录控制器提供了自动化程度。     

涉县地震台伸缩仪EW向观测精度的提高途径

涉县地震台伸缩仪EW向自2001年数字化改造以来,其观测精度呈逐年下降的趋势,为了找出原因并解决这个问题,我们从改造供电系统、加强洞室密封、改进避雷措施、更换仪器传感系统等方面展开工作,有效地去除了伸缩仪观测曲线的"毛刺"现象,杜绝了雷害.提高了伸缩仪Ew向的观测精度.     

石英伸缩仪安装中的准直技术

一、利用经纬仪和水准仪联合控制石英管的方法石英伸缩仪SSY—Ⅱ型由石英管基线、传感器、信号处理记录系统和标定部分组成。基线采用溶融石英管,每隔1.5米用吊丝将其悬挂在金属支架上,构成长度大于20米的基线部份。基线的一端固定在基岩上,另一端则为传感器端。仪器利用石英管长度的稳定性,测量地壳水平向的伸缩变化。测量精度可达10~(-7)数量级。由于精度要求高,定位时要求石英管基线在总长     

易县地震台形变资料的一致性及差异性分析

文章选取易县地震台DSQ型水管倾斜仪、VS型垂直摆倾斜仪、SS-Y型伸缩仪、TJ-2型体积应变仪多年的观测资料,采用形态对比法及Venedikov调和分析法讨论潮汐因子、相位滞后等参数,对统计结果进行一致性和差异性分析。结果表明,同一观测环境下,不同仪器相同物理量观测不一致,同物理量观测的潮汐因子幅度、精度不一致。     

CTM-DI磁力仪的使用与维护

大连地震台“九五”期间配置的CDM-DI磁力仪（简称DI仪）由中国科学院地球物理研究所研制。该仪器经过2000年考核运行1年，观测精度较高。于2001年1月1日起正式作为我台绝对观测仪投入使用，2001年9月1日开始近零法观测。 1 DI仪在地磁台站模拟观测系统中的应用 1.1 DI仪在指零法观测中的应用 2001年我台应用DI仪作为绝对观测仪器，使用指零法完整观测1年，精度、稳定性良好，表1为2001年我台DI仪指零法模拟观测基线月剩余方差精度表。 2001年我台模拟记录仪运行稳定、状态良好。应用DI仪与其配合，所得基线精度良好，大大高于规范…     

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.     

Information for authors

正SCIENCE CHINA Earth Sciences,an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press and Springer,is committed to publishing high-quality,original results in both basic and applied research.     

INTERNATIONAL RESEARCH AND TRAINING CENTER ON EROSION AND SEDIMENTATION(IRTCES)

正Director:Shangfu Kuang,China Vice-directors:Chunhong Hu,China Duihu Ning,China Guangquan Liu,China The International Research and Training Center on Erosion and Sedimentation(IRTCES)was jointly set up by the Government of China and UNESCO on July 21,1984.It aims at the promotion of international exchange of knowledge and cooperation in the studies of erosion and     

Calendar of events

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Dynamic process-response model of river channel development

Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape.