Detecting and analyzing clusters of low-birth weight incidence using exploratory spatial data analysis     

Steven Reader 《GeoJournal》2001,53(2):149-159

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Overview of US Minerals Management Service Activities in Deepwater Research     

Robert LaBelle   《Marine pollution bulletin》2001,43(7-12):256-261

The US Minerals Management Service (MMS) is responsible for safe and environmentally sound management of offshore oil and gas resources. In recent years, there has been a tremendous increase in both activities and plans for deepwater development of these resources in the Gulf of Mexico (GOM). As the industry meets the enormous technical challenges involved, there is a concomitant effort to assure environmental protection of deep-ocean and coastal resources. This paper will outline the research planning and program currently underway to assess impacts, identify potential problems, and discover more about unknown resources of the deep ocean.  相似文献   

A new inverse method and application to ocean data     

魏恩泊  田纪伟  顾国庆 《中国科学D辑(英文版)》2001,44(6):490-497

A new method is proposed to inverse normalization data of hidden variables in a dynamical system by embedding a time series in multidimensional spaces and applying a normalization analysis to the conditional probability density of points in the reconstructed phase spaces. The method is robust in the application to Lorenz system and 4-dimensional R?ssler system by testing quantitatively and qualitatively the correlation coefficient between inverse data and original data in time domain and in frequency domain, respectively. By applying the method to analyzing the South China Sea data, the normalization data of wind speed is extracted from the sea surface temperature time series.  相似文献   

A modeling study on the controlling factors of seismic source distribution and their strength index——Practical analyses of the seismic environmental factors of the Honghe fault     

张超  谢富仁  张世民 《地震学报(英文版)》2001,14(2)

IntroductionThe tectono-physical background and dynamic environmental features of strong earthquakes have long been studied from different viewpoints by seismologists both in domestic and abroad. Many controlling factors include the crust structure, lithological environment, tectonic conditions, the stress state, heat flow distribution and hydrodynamic effects at depth, etc. Some of the studies have established a foundation for researching and recognizing the spatial distribution of potential …  相似文献   

Gravity field separation, density inversion and crustal tectonics in Kang-Dian region     

蒋福珍  方剑 《地震学报(英文版)》2001,14(4):417-424

IntroductionTethys-Himalya tectonic belt extends from west to east across Europe, Asia and Africa, and stops at the longitude of 104(E in China. The famous North-south active tectonic belt located in China is a part of China-Mongolia central-axis strong earthquake belt and the huge crustal thickness undulation belt. The tectonic belt is a strong extrusion, tension and shear region. It is synthesized by topography gradient belt, faults, Cenozoic basin and strong earthquake belt on north-so…  相似文献   

Earth’s density flattening and hypothesis of latitudinal normal density     

Hao Xiaoguang  Xu Houze  LIU Dajie 《中国科学D辑(英文版)》2001,44(8):673-679

In this paper, the definition of latitudinal density and density flattening of the level ellipsoid is given, and integral formulas of latitudinal density for pole gravity and equator gravity are derived. According to the pole gravity condition and equator gravity condition for the level ellipsoid, latitudinal density distribution function of the level ellipsoid is obtained. It is proved mathematically that latitudinal density of the earth’s equator is larger than that of the pole, the earth’s density flattening calculated preliminarily is 1/322, and hypothesis of the earth’s latitudinal normal density is further proposed, so that theoretical preparation for studying the forming cause of the earth gravity in problems such as continent drift, mantle convection, and submarine extension is made well.  相似文献   

Transition To Geostrophic Turbulence In The Laboratory, And As A Paradigm In Atmospheres And Oceans     

Peter L. Read 《Surveys in Geophysics》2001,22(3):265-317

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Evaluation of seismic energy demand     

Gaetano Manfredi 《地震工程与结构动力学》2001,30(4):485-499

In this paper, a method is proposed in order to obtain a simplified representation of hysteretic and input energy spectra. The method is based on the evaluation of the equivalent number of cycles correlated to the earthquake characteristics by the proposed seismic index I_D. This procedure allows us to obtain peak values of the hysteretic and input energy that depend on the demanded ductility, on the seismic index I_D and on the peak pseudo‐velocity. The assessment of the input energy represents a first step towards the definition of a damage potential index capable of taking into account the effect of the duration of the ground motions. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Inelastic buildings with tuned mass dampers under moderate ground motions from distant earthquakes     

P. Lukkunaprasit  A. Wanitkorkul 《地震工程与结构动力学》2001,30(4):537-551

The effectiveness of tuned mass dampers (TMD) in vibration control of buildings was investigated under moderate ground shaking caused by long‐distance earthquakes with frequency contents resembling the 1985 Mexico City (SCT) or the 1995 Bangkok ground motion. The elastic–perfectly plastic material behaviour was assumed for the main structure, with linear TMDs employed by virtue of their simplicity and robustness. The accumulated hysteretic energy dissipation affected by TMD was examined, and the ratio of the hysteretic energy absorption in the structure with TMD to that without it is proposed to be used, in conjunction with the peak displacement ratio, as a supplementary TMD performance index since it gives an indication of the accumulated damage induced in the inelastic structures. For the ground motions considered, TMD would be effective in reducing the hysteretic energy absorption demand in the critical storeys for buildings in the 1.8–2.8 s range. The consequence is reduction in damage of the buildings which would otherwise suffer heavy damage in the absence of TMD, resulting in economical restorability in the damage control limit state. This is of practical significance in view of the current trend toward performance‐based design. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Evaluation of response and energy in actively controlled structures     

Kevin K. F. Wong  Rong Yang 《地震工程与结构动力学》2001,30(10):1495-1510

A computational method of energy evaluation is derived to study the elastic responses and energy distribution of actively controlled single‐degree‐of‐freedom (SDOF) structures during earthquakes. Contrary to the common perception that applying active control force pumps energy into the structure, the applied control force can actually reduce the energy in the structure by reducing the input energy from earthquakes to the structure. In addition, applying control force can dissipate a large amount of energy in the structure when this control force is applied in the direction opposite to the displacement and velocity responses. To demonstrate this energy mechanism in active controlled structures, the two most popular control algorithms, optimal linear control (OLC) and instantaneous optimal control (IOC) algorithms, are used to calculate the control response and energy spectra. One‐step time delay is incorporated into the algorithms to take into consideration the practical aspect of active control. The effects of different earthquakes and damping ratios on control energy and response spectra are studied. These studies show that both OLC and IOC are very effective in reducing the structural displacement and velocity responses by reducing the input earthquake energy as well as dissipating a large amount of energy in the structure. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献