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1.
“用压缩质面法反演重力资料以估算地壳构造”一文发表在1977年第一期《地球物理学报》上。在应用过程中,我们发现一些问题,在此提出讨论。 1.平均密度问题 假定“深部重力异常”是由康腊界面与莫霍界面的起伏引起的(为了便于讨论,其它界面从略)。我们根据文献[1]作者常用的参数,做了两个起伏界面与对应的重力异常图(见 相似文献
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在“DSF”理论的基础上,本文将压缩观测水层的构造应力增量扩展成是时间任意函数的持续力情况,用这种持续力压缩水层产生喷涌的机理更具有普遍意义,而以单一矩形力为基础的成因理论,仅仅是持续力情况下的一个特例。本文介绍的就是这种扩展的“DSF”理论(The Extend Deformation Seepage Flow Theory)。本文还就扩展的“DSF”理论的意义等进行了讨论。 相似文献
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本文探讨了二种地震数据实时自适应压缩方法。自适应采样是我们在总结传统的采样方法的基础上,结合地震信号频率变化特点,对地震信号所采取的一种波形压缩方法。自适应增量编码ADPCM法则在自适应采样压缩的基础上将地震数据又压缩了二倍,进一步提高了压缩效果。两种方法有力配合,使短、中长、长周期地震记录分别压缩了12倍、30倍、10倍以上。压缩恢复波形无论在时域分析(相关系数达0.997以上)还是在频域分析,失真都非常小,基本达到无畸变压缩。上述两种方法算法简单,计算量小,易于地震数据的高速采集、传输及记录。自适应采样法目前已应用于国家地震局地球物理所六室研制的BSO系统中。 相似文献
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在地震资料处理领域,数据的压缩和重建是非常重要的问题,但往往由于数据的严重缺失或采样原因而达不到理想的效果.新发展起来的压缩感知理论为重建欠采样数据提供了可能,而选用合适的采样方法是其中的关键技术之一.本文基于傅里叶变换和压缩感知理论,采用泊松碟采样,对不完整地震数据进行恢复重建.数值实验表明,与传统的单纯随机采样方法相比,泊松碟采样方法在保持采样随机性的同时,使采样点的分布更加均匀,有效地调节了采样间距,从而达到更好的恢复效果,可以有效地指导地震数据采集设计及重建. 相似文献
5.
从地形变资料探讨丽江7.0级地震的前兆特征 总被引：2，自引：0，他引：2
讨论了地震孕育发生的物理机制是“拉疏隆起－压缩凹陷”模式的形成机理及其特征;根据这一理性认识,应用丽江７．０级地震之前滇西地区的地形变资料,较确切出得出了本区有强震发生,并且可以认为孕震体是在丽江至玉龙雪山东麓地区;根据发震前夕所观测到孕震体的“拉疏隆起－压缩凹陷”的区域大小与幅度值及岩层的弹性应变,可近似计算震级的大小。 相似文献
6.
本文提出了压缩存储约化法求解对称变带宽方程组的一种实用计算公式和程序编制。该方法的计算精度高于广义平方根分解法并探讨了压缩存储约化法在水准网间接平差中的应用。利用法方程系数阵的变带宽稀疏对称性,应用该法可使元素存入量由原来的n×n减少到5n—100n,大大节省了存储量和计算时间。 文中提出了作水准网的静态与动态秩亏网平差时,由程序自动提取法方程系数阵的压缩存储信息、用观测值信息直接累加式组成压缩存储的法方程系数阵及协因数阵的快速求出等具体计算方法。这些方法通用于任何水准网,可编通用程序。 文中列举了应用压缩存储约化法的效益,在PDP—11/23机(内存256KB)上双精度解算1366阶法方程的动态秩亏网平差,只占终端时间158分钟。而解算502阶法方程的静态平差,仅占终端时间9分钟。 本文最后给出了算例。 相似文献
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正不动产登记事关产权保护、市场主体、经济体制改革和营商环境优化等方方面面,涉及千家万户,影响各行各业。不久前,国务院办公厅发布了《关于压缩不动产登记办理时间的通知》(以下简称《通知》),提出要充分利用互联网、大数据、人脸识别、在线支付等技术,推行“互联网+不动产登记”。到2020年底前,全国所有市县一般登记、抵押登记业务办理时间力争全部压缩至5个工作日 相似文献
10.
利用岩石声发射活动性的应力履历效应估计地壳应力 总被引：3，自引：0，他引：3
引言 岩石的声发射活动性能够“记忆”岩石所受过的最大应力,这种效应称为凯赛效应。它是Kaiser,J.1953年在金属材料的拉伸试验中首先发现的。后来Goodman(1963)、金川忠等(1977)在岩石压缩试验中也证实了凯赛效应的存在。金川忠等(1978)认为,利用定向钻孔岩芯制备的定向试件声发射活动性的变化,可以确定地壳应力状态。这个应力状态与同一地点的套芯法和水压致裂法原地应力测量结果相比较,有可能估计测量地区应力状态的变化趋势。这对于判断天然断层的稳定性具有十分重要的意义。这个 相似文献
11.
Occurrence number of red tides in Osaka Bay in Japan is more than 20 cases every year. Diatom red tide was dominant in Osaka Bay, but the non-diatom red tide was dominant in early 1990s. Therefore, the material cycling in Yodo River estuary in Osaka Bay during August from 1991 to 2000 was analyzed by using the numerical ecosystem model and field observation data to clarify the reasons of change in red tide species. Year-to-year variation in calculated concentration ratio of diatom to non-diatom corresponds to the variation in observed ratio of red tide days of diatom to non-diatom. Limiting nutrient of primary production is phosphate over the period. Diatom dominated from 1991 to 1993, but it was difficult for non-diatom to grow due to the limitation by physical condition. Non-diatom was able to grow because of good physical and nutrient conditions from 1994 to 1996. And diatom dominated again under the good physical condition, and phosphorus supply was not enough for non-diatom to grow from 1998 to 2000. Phosphate concentration in the lower layer of Yodo River estuary was important to the variation in red tide species in the upper layer of Yodo River estuary. 相似文献
12.
Use of GRACE determined secular gravity rates for glacial isostatic adjustment studies in North-America 总被引：3，自引：1，他引：2
Monthly geopotential spherical harmonic coefficients from the GRACE satellite mission are used to determine their usefulness and limitations for studying glacial isostatic adjustment (GIA) in North-America. Secular gravity rates are estimated by unweighted least-squares estimation using release 4 coefficients from August 2002 to August 2007 provided by the Center for Space Research (CSR), University of Texas. Smoothing is required to suppress short wavelength noise, in addition to filtering to diminish geographically correlated errors, as shown in previous studies. Optimal cut-off degrees and orders are determined for the destriping filter to maximize the signal to noise ratio. The halfwidth of the Gaussian filter is shown to significantly affect the sensitivity of the GRACE data (with respect to upper mantle viscosity and ice loading history). Therefore, the halfwidth should be selected based on the desired sensitivity.It is shown that increase in water storage in an area south west of Hudson Bay, from the summer of 2003 to the summer of 2006, contributes up to half of the maximum estimated gravity rate. Hydrology models differ in the predictions of the secular change in water storage, therefore even 4-year trend estimates are influenced by the uncertainty in water storage changes. Land ice melting in Greenland and Alaska has a non-negligible contribution, up to one-fourth of the maximum gravity rate.The estimated secular gravity rate shows two distinct peaks that can possibly be due to two domes in the former Pleistocene ice cover: west and south east of Hudson Bay. With a limited number of models, a better fit is obtained with models that use the ICE-3G model compared to the ICE-5G model. However, the uncertainty in interannual variations in hydrology models is too large to constrain the ice loading history with the current data span. For future work in which GRACE will be used to constrain ice loading history and the Earth's radial viscosity profile, it is important to include realistic uncertainty estimates for hydrology models and land ice melting in addition to the effects of lateral heterogeneity. 相似文献
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Shuwei Zheng Huanlong Luo Jiayue Zhang Heqin Cheng Zijun Li Yugai Ma Shuaihu Wu Enfeng Liu 《国际泥沙研究》2022,37(4):484-492
The Yangtze River(YR), similar to most large rivers in the world, has experienced significant changes in its depositional environment due to anthropogenic disturbances and climatic influences in recent decades. However, knowledge of how the river channel and bed deformation respond to these changes in the uppermost part of the lower YR, a 200-km-long branched channel, is limited. In the current study,historical bathymetric data collected from 1992 to 2013 and high-resolution multibeam echo sound... 相似文献
14.
S.A. Thorpe 《地球物理与天体物理流体动力学》2013,107(1):59-74
The effects of finite amplitude are examined in two-dimensional, standing, internal gravity waves in a rectangular container which rotates about a vertical axis at frequency f/ 2. Expressions are given for the velocity components, density fluctuations and isopycnal displacements to second order in the wave steepness in fluids with buoyancy frequency, N , of general form, and the effect of finite amplitude on wave frequency is given in an expansion to third order. The first order solutions, and the solutions to second order in the absence of rotation, are shown to conserve energy during a wave cycle. Analytical solutions are found to second order for the first two modes in a deep fluid with N proportional to sech( az ), where z is the upward vertical coordinate and a is scaling factor. In the absence of rotation, results for the first mode in the latter stratification are found to be consistent with those for interfacial waves. An analytical solution to fourth order in a fluid with constant N is given and used to examine the effects of rotation on the development of static instability or of conditions in which shear instability may occur. As in progressive internal waves, an effect of rotation is to enhance the possibility of shear instability for waves with frequencies close to f . The analysis points to a significant difference between the dynamics of standing waves in containers of limited size and progressive internal waves in an unlimited fluid; the effect of boundaries on standing waves may inhibit the onset of instability. A possible application of the analysis is to transverse oscillations in long, narrow, steep-sided lakes such as Loch Ness, Scotland. 相似文献
15.
Two closely related scleractinian coral species, Porites cylindrica and Porites rus, were transplanted to two different locations: the natural environment on the reef flat, and culture tanks on land. The use of tanks enabled the regulation of certain environmental factors, and, hence, the evaluation of specific responses of the corals to these factors. For both species, growth and survival were much better in the field than in the land-based tanks most probably due to unrestricted water circulation. Since the two species were subjected to identical experimental treatments, it was possible to distinguish inherent differences between them in terms of responses to external variables. Porites cylindrica was more susceptible than P. rus to predation by corallivores. Predators, as well as grazers, occurred in significant numbers in the field, but not in the land-based tanks. Porites rus, on the other hand, succumbed more readily to overgrowth by macroalgae which thrived in the culture tanks presumably because of significantly higher nutrient levels and the conspicuous absence of grazers. These results have broader ecological implications because of accelerated environmental changes taking place in present-day reefs due to human impact. Major examples are eutrophication and alterations in water circulation which frequently result in sub-optimal conditions for coral survival and growth. 相似文献
16.
Field-based experiments were designed to investigate the release of naturally occurring, low to moderate (< 50 microg/L) arsenic concentrations to well water in a confined sandstone aquifer in northeastern Wisconsin. Geologic, geochemical, and hydrogeologic data collected from a 115 m2 site demonstrate that arsenic concentrations in ground water are heterogeneous at the scale of the field site, and that the distribution of arsenic in ground water correlates to solid-phase arsenic in aquifer materials. Arsenic concentrations in a test well varied from 1.8 to 22 microg/L during experiments conducted under no, low, and high pumping rates. The quality of ground water consumed from wells under typical domestic water use patterns differs from that of ground water in the aquifer because of reactions that occur within the well. Redox conditions in the well can change rapidly in response to ground water withdrawals. The well borehole is an environment conducive to microbiological growth, and biogeochemical reactions also affect borehole chemistry. While oxidation of sulfide minerals appears to release arsenic to ground water in zones within the aquifer, reduction of arsenic-bearing iron (hydr)oxides is a likely mechanism of arsenic release to water having a long residence time in the well borehole. 相似文献
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Buruaem LM Hortellani MA Sarkis JE Costa-Lotufo LV Abessa DM 《Marine pollution bulletin》2012,64(3):479-488
Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecém) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. 相似文献
18.
Tjeerd H. Van Andel 《Earth and Planetary Science Letters》1975,26(2):187-194
From late Jurassic to early Cenozoic time the calcite compensation depth (CCD) in the world oceans was shallow (above 4000 m). About 40 m.y. ago it dropped to about 4500 m, sharply in the Indian and Pacific oceans and gradually in the Atlantic. In the early Miocene it began to rise again, reaching a very shallow peak 10–15 m.y. ago, then descended to its present deep position. In the Pacific, fluctuations during the last 40 m.y. appear to result mainly from changes in bottom-water structure related to the progressive glaciation of the Antarctic and Arctic regions. Analogous explanations hold for CCD fluctuations during this period in the Indian and Atlantic oceans. The very shallow CCD prior to about 50 m.y., on the other hand, cannot be explained in this manner but must be attributed either to a low input of calcium in the oceans from deeply weathered continents or, more probably, to large changes in the distribution of carbonate deposition between shallow and deep seas. 相似文献
19.
The Mondego estuary (Portugal) suffered major changes in environmental quality due to eutrophication, however, in the late 1990s a restoration project was implemented in order to return the system to its original condition. The main goal of this paper is to evaluate the ecosystem response to the restoration measures applied at three different levels: water quality, primary producers and primary consumers.In post-restoration period a clear decline was observed in dissolved inorganic nitrogen which was reflected in the gradual recovery of Zostera noltii and a concomitant decline in green macroalgae.Macrobenthic assemblages responded variably to the recovery process. In the seagrass bed and intermediate area, there was a large increase in total biomass, but in the eutrophic area species diversity increased. Despite improvement in the ecological status of the system, full recovery has not been achieved yet, possible due to hysteresis in the dynamics of this system. 相似文献
20.
Like many countries in the world, China is also facing serious problems of marine pollution in the coastal zone. The prevailing concern is eutrophication of the coastal water due to river inputs and, in some bays, also due to the over-expansion of aquaculture. As part of the marine pollution research activities in China, applications of mathematical models are also widely used, both to understand the present and to project the future. In this paper, selected Chinese works are reviewed, especially with respect to the effort in reducing the errors introduced in the numerical treatment of the water quality equation. 相似文献