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1.
《Geophysical Prospecting》1967,15(4):702-702
Book review in this article
Handbuch der Physik/Encyclopedia of Physics, Ed.: S. Flügge
The Aurora. By S.-I. Akasofu, S. Chapman and A. B. Meinel.
Time-Variations of Cosmic Rays. By S. E. Forbush.
Magnetic Properties of Rocks and Minerals. By T. Nagata. 相似文献
Handbuch der Physik/Encyclopedia of Physics, Ed.: S. Flügge
The Aurora. By S.-I. Akasofu, S. Chapman and A. B. Meinel.
Time-Variations of Cosmic Rays. By S. E. Forbush.
Magnetic Properties of Rocks and Minerals. By T. Nagata. 相似文献
2.
Boubacar KANE Pierre Y. JULIEN 《国际泥沙研究》2007,22(2):114-119
An extensive database of reservoir sedimentation surveys throughout continental United States is compiled and analyzed to determine specific degradation SD relationships as function of mean annual rainfall R, drainage area A, and watershed slope S. The database contains 1463 field measurements and specific degradation relationships are defined as function of A, R and S. Weak trends and significant variability in the data are noticeable. Specific degradation measurements are log normally distributed with respect to R, A, and S and 95% confidence intervals are determined accordingly. The accuracy of the predictions does not significantly increase as more independent variables are added to the regression analyses. 相似文献
3.
《Astronomy& Geophysics》2008,49(4):4.16-4.18
The 2008 Rishbeth Prize for the best poster displayed at the National Astronomy Meeting in Belfast was awarded jointly to "A superposed epoch analysis of auroral evolution during substorm growth, onset, and recovery" by S E Milan, A Grocott, C Forsyth, S M Imber, P D Boakes and B Hubert. Steve Milan summarizes. 相似文献
4.
Francesca Vergari Francesco Troiani Hazel Faulkner Maurizio Del Monte Marta Della Seta Sirio Ciccacci Paola Fredi 《地球表面变化过程与地形》2019,44(1):273-286
This paper explores the effectiveness of the widely-used functional relationship between drainage area (A in m2) and slope (S in m/m) to identify local process domains and aid interpretation of process interactions in a complex badland landscape. In order to perform this investigation, a series of sub-basins tributary to the Formone River in the Orcia catchment (central Italy) were selected as a suitable study area within which to explore our questions, given these basins' general representativeness of local terrain, the availability of a high resolution digital terrain model and previous extensive geomorphological research. Eroding basins containing both calanchi and landslides are common in the sub-humid badland landscape of central Italy, where field observation identifies a complex pattern of erosive processes associated with a history of uplift, despite which parts of the local landscape appear disconnected. Results reveal that the shape of all S–A curves (plotted using S data binned on log A) is comparable with that described in the literature, although sub-basins containing calanchi generally plot with higher S values than non-calanchi ones, except in the ‘fluvial’ section of the plots. Second, when viewed on total data (non-binned) S–A plots, landslide source area domains and calanchi domains are entirely coincident in all basins, supporting a cause–effect relationship. Additional plotting of the frequency characteristics of the raw data in a new way supports the interpretation that calanchi frequently initiate in landslide scars. In general though, although the S–A plots can contribute to the disentanglement of geomorphological behaviour in some complex erosional landscapes, it became apparent that in this landscape, process domains do not separate out with clarity along the A axis as suggested by theory. Despite this, an alternative, broader-scale morphoevolutive model can be proposed for the development of within-landslide calanchi, driven by changes to basin connectivity to the base channel. © 2018 John Wiley & Sons, Ltd. 相似文献
5.
Assessment of the impact of different vegetation patterns on soil erosion processes on semiarid loess slopes 总被引：6，自引：0，他引：6 
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下载免费PDF全文 Tianjiao Feng Wei Wei Liding Chen Jesús Rodrigo‐Comino Chen Die Xinran Feng Kemeng Ren Eric C. Brevik Yang Yu 《地球表面变化过程与地形》2018,43(9):1860-1870
Soil erosion hinders the recovery and development of ecosystems in semiarid regions. Rainstorms, coupled with the absence of vegetation and improper land management, are important causes of soil erosion in such areas. Greater effort should be made to quantify the initial erosion processes and try to find better solutions for soil and water conservation. In this research, 54 rainfall simulations were performed to assess the impacts of vegetation patterns on soil erosion in a semiarid area of the Loess Plateau, China. Three rainfall intensities (15 mm h‐1, 30 mm h‐1 and 60 mm h‐1) and six vegetation patterns (arbors‐shrubs‐grass ‐A‐S‐G‐, arbors‐grass‐shrubs ‐A‐G‐S‐, shrubs‐arbors‐grass ‐S‐A‐G‐, shrubs‐grass‐arbors ‐S‐G‐A‐, grass‐shrubs‐arbors ‐G‐S‐A‐ and grass‐arbors‐shrubs ‐G‐A‐S‐) were examined at different slope positions (summits, backslopes and footslopes) in the plots (33.3%, 33.3%, 33.3%), respectively. Results showed that the response of soil erosion to rainfall intensity differed under different vegetation patterns. On average, increasing rainfall intensity by 2 to 4 times induced increases of 3.1 to 12.5 times in total runoff and 6.9 to 46.4 times in total sediment yield, respectively. Moreover, if total biomass was held constant across the slope, the patterns of A‐G‐S and A‐S‐G (planting arbor at the summit position) had the highest runoff (18.34 L m‐2 h‐1) and soil losses (197.98 g m‐2 h‐1), while S‐A‐G had the lowest runoff (5.51 L m‐2 h‐1) and soil loss (21.77 g m‐2 h‐1). As indicated by redundancy analysis (RDA) and Pearson correlation results, a greater volume of vegetation located on the back‐ and footslopes acted as effective buffers to prevent runoff generation and sediment yield. Our findings indicated that adjusting vegetation position along slopes can be a crucial tool to control water erosion and benefit ecosystem restoration on the Loess Plateau and other similar regions of the world. Copyright © 2018 John Wiley & Sons, Ltd. 相似文献
6.
JoAnn Browning 《地震工程与结构动力学》2002,31(6):1267-1280
A maximum allowable period criterion is used to determine reasonable stiffness requirements for reinforced concrete frames with the seismicity associated with central and eastern U.S. A general relationship is developed to describe the displacement demand expected for central and eastern U.S. based on a survey of available ground motions, opinions of seismologists, and code‐based provisions. A series of hypothetical reinforced concrete frames is proportioned using a maximum allowable period criterion and evaluated for expected maximum displacement response using non‐linear dynamic analyses and a suite of ground motions. Results indicate that for the reinforced concrete structural systems considered in the study, proportioning for gravity loads will provide sufficient stiffness in central and eastern U.S. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
7.
A project implemented to study the effects of space weather on the Finnish natural gas pipeline was started in August 1998. The aims of the project were (1) to derive a model for calculating geomagnetically induced currents (GIC) and pipe-to-soil (P/S) voltages in the Finnish natural gas pipeline, (2) to perform measurements of GIC and P/S voltages in the pipeline and (3) to derive statistical predictions for the occurrences of GIC and P/S voltages at different locations in the pipeline network.GIC and P/S voltage were recorded at a compressor station. The GIC measurement was made with two magnetometers, one right above the pipe, and another at the Nurmijärvi Geophysical Observatory about 30 km southwest. The largest GIC since November 1998 has been 30 A. The P/S voltage recording was stopped in May 1999, but GIC is still measured.GIC statistics were derived based on the recordings of the geomagnetic field at Nurmijärvi. The geoelectric field was calculated by using the plane wave model. This field was input to the general pipeline model resulting in the distribution of currents and P/S voltages at selected points in the pipeline. As could be expected, the largest P/S voltage variations occur at the ends of the pipeline network, while the largest GIC flow in the middle parts. 相似文献
8.
Impact of salt stress on the features and activities of root system for three desert halophyte species in their seedling stage 总被引：1，自引：0，他引：1
Linkage between belowground and aboveground sections of ecological system is mainly depending on root system. But root system is the parts of plant that people less understand. The absorption function of root system is closely related to their morphology and activity. Moreover root system can interact with the environmental stress under the adverse situation, and adjust its system to take adaptation responses in morphology and physiology to strengthen its survival chance. This research is focused on three desert halophyte species of H. ammodendron (C.A.Mey.) Bge., S. physophora Pall., and S. nitraria Pall. under solution culture, to study the differences of their root system morphology and activity in the seedling stage under varying salt concentration conditions. The study results show that: A certain salt concentration can promote development of these three halophytes; but rather high salt concentration will restrain their growth, in particular inhibit the root system development. Under the same salt concentration condition, S. nitraria Pall. grows fast and accumulates the largest amount of biomass. Under relatively low salt concentration, the length of axial root and the total length of root system of these three halophyte species are all increased; and compared to the checking samples, S. physophora Pall. occupies the top place of root system growth, but the high salt concentration will restrain the increase of total root length; among them, the impact intensity on S. physophora Pall. is lighter than to H. ammodendron (C.A.Mey.) Bge. and S. nitraria Pall. is lighter; the salinity does not bring distinct influence on the average diameter of root system of these three plant species, but trends to reducing the size; under the solution culture conditions, the middle and lower parts of the axial root of H. ammodendron (C.A.Mey.) Bge. and S. physophora Pall. are rather equally distributed, but the central zone of S. nitraria Pall. root system is more significantly increased than the upper and lower zones; salt concentration does not bring significant impact on the root system spatial distribution of each species. The root activity of the three plants is increased along with the increase of the salt concentration. When the salt concentration is low, the root activity is not significantly increased; but when the salt concentration is high, the root activity is increased significantly. The experimental results show that the saline tolerance capacity of H. ammodendron (C.A.Mey.) Bge. is lower than the other two species, and the capacity of S. physophora Pall. ranks the top place. 相似文献
9.
鉴于中国与美国、日本、俄罗斯等主要地震国家过去三四十年地震预报研究工作的科学思路和技术途径比较接近,主要区别是,中国始终坚持“边研究、边预报”,而其他国家,尤其是西方国家以科学研究为主,本文着重分析了“边研究、边预报”的必要性、优越性与带来的差距,并提出了3点发展建议。 相似文献
10.
云南大姚6.2级、6.1级地震前电磁异常特征分析 总被引：1，自引：1，他引：0
李树华 《地震地磁观测与研究》2004,25(5):1-10
对2003年云南大姚6．2级、6．1级地震前云南磁电资料分析研究,结果表明,震前地磁Z、D分量及地电阻率、自然电位出现明显异常。6．1级地震前出现的异常比6．2级地震前出现的异常更为显著,两次地震发生前均出现多组相对速率变化超差异常。6．1级地震前一周,元谋自然电位NS、EW向同时出现大幅度下降的临震异常。分析总结这些异常特征,对云南地区未来中强地震的震情分析和短临跟踪有一定的预报意义。 相似文献
11.
The sulphur cycle in the sediment of the Venice canal network was investigated by considering the sulphate reduction rate (SRR) and the distribution of sulphur compounds, in both pore water and sediment. Sulphate reduction (SR) is the main process in the metabolism of the organic matter supplied to the network by untreated urban effluents. Although it might account for the decomposition of only a limited percentage of the total organic-C inputs, the estimated rates are among the highest observed in coastal sediments. Measured rates range from 0.26 to 0.99 micromolcm(-3)d(-1), while mean annual values, estimated by a diagenetic model, vary from 0.16 to 0.43 micromolcm(-3)d(-1). The speciation of S in the sediment reveals that pyrite-S is the most abundant component of the total reduced S pool, whereas acid volatile sulphides and elemental sulphur together account for less than 45%. A preliminary budget indicates that the rate of burial of solid-phase S is small compared to the S produced by SR (from 10 to 25%). A large amount of reduced S is then lost from the canal deposits to be re-oxidised at the sediment-water interface or in the overlying water column. 相似文献
12.
提出了联合使用反射波横波Ｓ１１,Ｓｉｌ,Ｓｉ２在地震台网较疏的地区求解地震震源深度的原理和方法,并以新丰江水库区１２次地震为例,对该方法的结果进行检验。结果表明,利用反射皮法测定的震源深度与新丰江遥测台网的测定结果吻合较好。 相似文献
13.
利用CHAMP卫星轨道和加速度计数据推求地球重力场模型的一种有效方法是能量守恒方法.本文基于能量守恒方程,推导了整体求解尺度、偏差、积分常量和位系数的计算公式,提出了整体求解位系数、积分常量、尺度和偏差参数的重力场恢复方法-改进的能量法.该方法摆脱了目前使用能量法时,必须预先通过其它外部手段标定加速度计数据以及积分常量通过近似计算获取的现状.基于德国慕尼黑技术大学(TUM)提供的约300天的CHAMP卫星几何法轨道和GFZ提供的加速度计数据,计算出了60×60阶地球重力场模型XISM-CHAMP1S,并与EIGEN-CG03C、EIGEN-CHAMP03S、EIGEN2、ENIGN1S、EGM96模型进行了比较.结果表明:XISM-CHAMP1S模型精度明显优于相同阶次EGM96、EIGEN1S和EIGEN2,与同阶次的EIGEN-CHAMP03S模型精度最为接近. 相似文献
14.
Sensitivity of seismic waves to structure 总被引：2，自引：0，他引：2
Luděk Klime? 《Studia Geophysica et Geodaetica》2012,56(2):483-520
We study how the perturbations of a generally heterogeneous isotropic or anisotropic structure manifest themselves in the wavefield, and which perturbations can be detected within a limited aperture and a limited frequency band. A short-duration broad-band incident wavefield with a smooth frequency spectrum is considered. In-finitesimally small perturbations of elastic moduli and density are decomposed into Gabor functions. The wavefield scattered by the perturbations is then composed of waves scattered by the individual Gabor functions. The scattered waves are estimated using the first-order Born approximation with the paraxial ray approximation. For each incident wave, each Gabor function generates at most 5 scattered waves, propagating in specific directions and having specific polarisations. A Gabor function corresponding to a low wavenumber may generate a single broad-band unconverted wave scattered in forward or narrow-angle directions. A Gabor function corresponding to a high wavenumber usually generates 0 to 5 narrow-band Gaussian packets scattered in wide angles, but may also occasionally generate a narrow-band P to S or S to P converted Gaussian packet scattered in a forward direction, or a broad-band S to P (and even S to S in a strongly anisotropic background) converted wave scattered in wide angles. In this paper, we concentrate on the Gaussian packets caused by narrow-band scattering. For a particular source, each Gaussian packet scattered by a Gabor function at a given spatial location is sensitive to just a single linear combination of 22 values of the elastic moduli and density corresponding to the Gabor function. This information about the Gabor function is lost if the scattered wave does not fall into the aperture covered by the receivers and into the legible frequency band. 相似文献
15.
《Advances in water resources》1998,21(5):339-350
A modeling approach is presented that optimizes separate phase recovery of light non-aqueous phase liquids (LNAPL) for a single dual-extraction well in a homogeneous, isotropic unconfined aquifer. A simulation/regression/optimization (S/R/O) model is developed to predict, analyze, and optimize the oil recovery process. The approach combines detailed simulation, nonlinear regression, and optimization. The S/R/O model utilizes nonlinear regression equations describing system response to time-varying water pumping and oil skimming. Regression equations are developed for residual oil volume and free oil volume. The S/R/O model determines optimized time-varying (stepwise) pumping rates which minimize residual oil volume and maximize free oil recovery while causing free oil volume to decrease a specified amount. This S/R/O modeling approach implicitly immobilizes the free product plume by reversing the water table gradient while achieving containment. Application to a simple representative problem illustrates the S/R/O model utility for problem analysis and remediation design. When compared with the best steady pumping strategies, the optimal stepwise pumping strategy improves free oil recovery by 11.5% and reduces the amount of residual oil left in the system due to pumping by 15%. The S/R/O model approach offers promise for enhancing the design of free phase LNAPL recovery systems and to help in making cost-effective operation and management decisions for hydrogeologists, engineers, and regulators. 相似文献
16.
提出了位场曲化平的新方法. 给定观测曲面S上的位场、S对下方水平面P的相对高程,确定P上的位场. 利用由P向上延拓到S的积分式,建立这两个面上位场及相对高程三者所满足的方程,它是第一类Fredholm积分方程. 用Fourier逆变换式把这一空间域积分式化为波数域积分式,再由指数函数的Taylor展开进一步化为级数式. 积分方程的解采用逐次逼近法迭代计算,即用S上的位场观测值作为P上位场的初始迭代值,用导出的级数式求得S上的位场计算值、由S上的位场观测值与计算值之差校正P上的位场,多次迭代,直到满足迭代终止准则. 我们还给出该积分方程的波数域迭代计算方法. 模型算例表明,重力异常曲化平的均方差和磁异常曲化平的均方差分别为0.0008 mGal和0.0019 nT,在主频为2.26 GHz的笔记本电脑运行,2048×2048数据量,计算时间是975 s. 野外磁场实际资料处理也证实这种方法的有效性. 相似文献
17.
18.
The chronology of deposits of the 1976 eruption of Augustine volcano, which produced pyroclastic falls, pyroclastic flows, and lava domes, is determined by correlating the stratigraphy with published records of seismicity, plume observations, and distant ash falls. Three thin air-fall ash beds (unit A1, A2 and A3) correlate with events near the beginning of the 1976 eruption on 22 and 23 January. On 24 January a small-volume, ash-cloud-surge deposit (unit S) accumulated over the north half of Augustine Island. A series of pumiceous pyroclastic flows represented by the lobate pumiceous deposits (unit F) occurred on 24 January and locally melted the snowpack to cause small pumice-laden floods. A thin ash bed (unit A4) was deposited on 24 January, and the main plinian eruption (unit P) occurred on 25 January. In middle to late February and again in mid April, lava domes were extruded at the summit accompanied by incandescent block-and-ash flows down the north flank. A hut near the north coast of the island was mechanically and thermally damaged by the small-volume ash-cloud surge of unit S before the eruption of the pumice flow of unit F; the metal roof was then penetrated by lithic fragments of the plinian fall of 25 January. Explosive eruptions in the early stage of an eruption-like that which deposited unit S — are important hazards at Augustine Island, as are infrequent debris avalanches and attendant tsunamis.deceased on 18 May 1980 相似文献
19.
这种方法的基本根据是:（一）震源地方岩体錯动的方向与横波离源时的方向、横波离源时的射綫方向在一个平面內;（二）横波在传播过程中,β角变化很小. 推导了由S波β角求横波离源时位移方向的公式.由两个台上的S波β角就可分別求得两个横波离源时的位移面,这两个面的交綫就是震源地方岩体錯动的方向。討論了在烏尔夫网上具体运用这一方法的作图.这就大大地簡化了求解的过程,便于大量处理数据。 相似文献
20.
1999年 1 1月 2 5日澄江发生 5.2级地震 ,2个月后的 2 0 0 0年 1月 2 7日在相邻的丘北 -弥勒地区发生了 5.5级地震 .分析了丘北—弥勒 5.5级地震的区域地震活动背景、地震孕育过程和地震活动性异常特征 ,为探讨在一次中强地震后如何预报后续地震提供了一个震例 . 相似文献