南海北部—观测点内潮特征的初步分析   总被引：2，自引：0，他引：2  

邱章  徐锡祯  龙小敏 《热带海洋学报》1996,(4)

采用功率谱分析、调和分析等方法，对南海北部－观测点连续９ｄ（１９８８年５月８—１６日）的温度。盐度和海流及跨越该期间较长的（１９８８年４月２４日－７月２２日）潮位资料进行了分析研究。结果表明，观测点存在着一种内潮现象，其波动的周期在２４ｈ左右，它传播的方向大体是偏北。  相似文献   

秦山核电站邻近水域生态特点     

何德华 《海洋学研究》1991,9(2):119-123

本文综述了1989年4月至1990年1月秦山核电站邻近水域生态调查结果,认为,该水域具暖温带强潮河口区生态特征。水体虽含丰富营养盐和充足溶解氧,由于同时存在着各种不利于生物繁殖生长的环境因子,表现为生物资源贫瘠、种类组成简单,测区所代表的强潮河口湾顶区属低生产力水域。  相似文献   

Analytical chemistry in monitoring the effects of aquaculture: one laboratory's perspective     

Zitko  V. 《ICES Journal of Marine Science》2001,58(2):486-491

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地震震源与灾害评估分析:中国四川2008年5月12日Ms 8.0汶川地震     

陈胜早 《高校地质学报》2008,14(3)

汶川5月12日8.0级地震在构造上起因于印度板块与欧亚板块以每年约5 cm的速度聚敛,并因此而引起青藏高原的地壳物质向四川盆地及中国东南大陆运移.主震震源及余震活动集中于以龙门山为中轴的一条长约350 km、宽约100 km的地震活动带.震源深度一般分布丁地壳脆性-韧性转换边界以上约10～20 km区间的地壳震源层之中,属浅源构造地震.主要震源机制与龙门山构造运动方式密切相关,以其地壳厚度向西急剧加厚、重力梯度带、高波速比(Vp/Vs～2.2)等深部异常及逆冲断层兼具走滑性质的地质构造为特征.在震源辐射、路径传播和场地效应研究的基础上,分别计算并比较了岩石和土壤条件下的地震响应谱,特别强调了土壤条件下的场地放大效应;同时对与地震安全性有关的一些问题如地质灾害、地震频谱设计、地震早期预警系统及中、长期至短期地震预报等进行了探讨;特别提供了一个由加权平均计算、以岩石条件下震波衰减模式为基础的地震频谱设计参考实例.地震构造与动力学研究可融人工程地质与环境工程等学科发展.经历汶川地震考验的一些新近设计和建设的工程项目可为今后改进工程建筑规范与标准提供重要而有益的参考.地震预报是当今一大难题,但需探索研究,不可懈怠.地震减灾与预防足目前比较切合实际的安全举措.  相似文献   

Analysis of COMPTEL gamma-ray burst locations and spectra     

R. M. Kippen  J. Ryan  A. Connors  M. McConnell  C. Winkler  L. O. Hanlon  V. Schönfelder  J. Greiner  M. Varendorff  W. Collmar  W. Hermsen  L. Kuiper 《Astrophysics and Space Science》1995,231(1-2):231-234

In its first three years of operation, the COMPTEL instrument on theCompton Gamma-Ray Observatory has measured the locations (mean accuracy 1°) and spectra (0.75-30 MeV) of 18 gamma-ray bursts and continues to observe new events at a rate of 1/month. With good angular resolution and sensitivity at MeV energies, the growing COMPTEL burst catalog is an important new piece of evidence in the on-going GRB mystery. The COMPTEL burst locations are consistent with an isotropic distribution of sources, yet the spatial coincidence of two of the bursts indicates the possibility of repetition. The COMPTEL burst spectra are in most cases consistent with a single power law model with spectral index in the range 2–3. However, two bursts show evidence of a spectral break in the MeV range. Measurement of rapid variability at MeV energies in the stronger bursts provides evidence that either the sources are nearby (within the Galaxy) or the gamma-ray emission is relativistically beamed. We present an overview of analysis results obtained from the COMPTEL burst catalog concentrating on the search for burst repetition and the implications of highly variable MeV emission.  相似文献   

Periodicities in natural remanent magnetization and palaeoclimatic records detected by walsh spectra     

J. G. Negi  R. K. Tiwari 《Pure and Applied Geophysics》1990,132(4):757-769

The time series consisting of nonsinusoidal Natural Remanent Magnetization (NRM) and palaeoclimatic variations for the past two million years have been spectrally examined by using a new Walsh transform technique. The results show statistically significant periodicities (at 95% confidence level) of approximately 92,000 years; 43,000 years and 21,000 years in the ensemble spectra of the NRM intensity (mineralogic) variations. These NRM periodicities are remarkably close to the well-known Milankovitch cycles. The ensemble spectra of palaeoclimatic records reveal only 41,000 years statistically significant (95%) periodicity corresponding to the obliquity cycle. The study suggests that NRM variations in deep sea sediments probably are more sensitive recorders of palaeoclimatic memory than the oxygen isotope variations.  相似文献   

干旱及高寒荒漠区土壤温湿度特征及相互影响的分析   总被引：3，自引：1，他引：3  

谢志清  刘晶淼  丁裕国  杜银 《高原气象》2005,24(1):16-22

根据黑河试验1991年6月20日～8月21日、1990年12月17日～2月15日每天48个时次和第二次青藏高原试验改则及狮泉河1998年全年每天24个时次的土壤温湿度资料，采用功率谱分析、PCA分析等方法，分析了干旱及高寒荒漠区两种典型下垫面土壤温湿度的时空分布特征及其相互作用。结果表明：土壤温度除日和年变化周期外还存在6～30天的不同周期；下垫面的非均匀性及其季节变化及温度梯度变化对土壤水分运动有很大的影响，冬季温度梯度变化对土壤含水量的影响大于夏季温度梯度对土壤含水量变化的影响，且温度梯度与水分运动方向相反。  相似文献   

大气边界层湍流温度序列的信息熵分析   总被引：2，自引：0，他引：2  

汪景烨  付遵涛  张霖  刘式达 《高原气象》2005,24(1):38-42

利用大气边界层内近地面的大气湍流温度时间序列，运用功率谱分析、信息熵分析等方法，分析了大气边界层内近地面的大气湍流特点，并对稳定层和不稳定层的大气湍流进行了对比。结果表明，信息熵和功率谱指数是区别稳定层结和不稳定层结大气边界层湍流特征的指标，对造成两者之间的差别做出了对应的解释。  相似文献   

Predicting grain protein content of winter wheat using remote sensing data based on nitrogen status and water stress     

《International Journal of Applied Earth Observation and Geoinformation》2005,7(1):1-9

Advanced site-specific knowledge of grain protein content of winter wheat from remote sensing data would provide opportunities to manage grain harvest differently, and to maximize output by adjusting input in fields. In this study, remote sensing data were utilized to predict grain protein content. Firstly, the leaf nitrogen content at winter wheat anthesis stage was proved to be significantly correlated with grain protein content (R² = 0.36), and spectral indices significantly correlated to leaf nitrogen content at anthesis stage were potential indicators for grain protein content. The vegetation index, VI_green, derived from the canopy spectral reflectance at green and red bands, was significantly correlated to the leaf nitrogen content at anthesis stage, and also highly significantly correlated to the final grain protein content (R² = 0.46). Secondly, the external conditions, such as irrigation, fertilization and temperature, had important influence on grain quality. Water stress at grain filling stage can increase grain protein content, and leaf water content is closely related to irrigation levels, therefore, the spectral indices correlated to leaf water content can be potential indicators for grain protein content. The spectral reflectance of TM channel 5 derived from canopy spectra or image data at grain filling stage was all significantly correlated to grain protein content (R² = 0.31 and 0.37, respectively). Finally, not only this study proved the feasibility of using remote sensing data to predict grain protein content, but it also provided a tentative prediction of the grain protein content in Beijing area using the reflectance image of TM channel 5.  相似文献   

地震作用下的灰坝液化特征及其动力稳定性分析--以安阳电厂为例   总被引：1，自引：0，他引：1  

李永乐  陈宇  彭成山  刘宪亮 《地质科技情报》2002,21(1):83-86

根据安阳电厂灰坝岩土工程性质及其动力学特性,建立了适合灰坝工程的动力分析模型并采用有限元法进行了动力分析.在此基础上,在不同工况条件下对灰坝进行了抗液化安全评价及抗震稳定性分析.研究表明,在不设碎石桩、无排渗体条件下,粉煤灰子坝的抗液化安全系数Ks＜1.25,将发生液化;在设碎石桩、有排渗体条件下,粉煤灰子坝的抗液化安全系数明显提高,Ks≥1.25,不会发生液化.抗震稳定性分析表明,在上述两种工况条件下灰坝是稳定的.  相似文献