Prospective Cohort Study


 The spectral ratio between horizontal and vertical components (H/V ratio) of microtremors measured at the ground surface has been used to estimate fundamental periods and amplification factors of a site, although this technique lacks theoretical background. The aim of this article is to formulate the H/V technique in terms of the characteristics of Rayleigh and Love waves, and to contribute to improve the technique. The improvement includes use of not only peaks but also troughs in the H/V ratio for reliable estimation of the period and use of a newly proposed smoothing function for better estimation of the amplification factor. The formulation leads to a simple formula for the amplification factor expressed with the H/V ratio. With microtremor data measured at 546 junior high schools in 23 wards of Tokyo, the improved technique is applied to mapping site periods and amplification factors in the area.

Ground Motion Characteristics Estimated from Spectral Ratio between Horizontal and Verticcl Components of Mietremors.

Interpretation theory in applied geophysics: Grant, F S ... Interpretation theory in applied geophysics Unknown Binding – January 1, 1965 5.0 out of 5 stars 1 rating. See all formats and editions Hide other formats and editions. The Amazon Book Review Book recommendations, author interviews, editors' picks, and more. Read it now. Enter your mobile number or email address below and we'll send you a ...

Interpretation Theory in Applied Geophysics Grant (McGraw-Hill, 140s.)

Lunar sourcebook. A user's guide to the moon

Ground penetrating radar (GPR) is a tool for indirectly looking at underground objects (such as graves), gravel and sand layers, and other underground structures. The information or data received by GPR is like an x-ray or map of the underground. In fact, GPR uses electromagnetic (EM) waves, as xray machines do, but GPR uses radio waves, which have a longer wavelength (see Figure A1). The wavelength, or the length of one wave, is the fundamental difference between the forms of electromagnetic energy. For example, the wavelength of x-rays range from about 10 billionths of a meter to about 10 trillionths of a meter, whereas radio waves can be a few meters long.

Ground Penetrating Radar

. This paper explores how indigenous people rely on traditional ecological knowledge (TEK) as a means to adapt to climate change. We focus on the observation, interpretation, and adaptation of natural phenomena among farmers from Baojiatun in the karst depression of central Guizhou, where the Han people have settled for more than 600 yr. First, the farmers are culturally rooted in ethics of nature worship and ancestor reverence, forming a community that is sensitive to natural phenomena and governed by local rules and regulations. Second, TEK has a special use in that the indigenous people are not worried about climate change itself because they view their own knowledge system as sufficient to aid adaptation. Third, the properties of TEK are critical resources for socioecological resilience to the impacts of climate change, including a keen observation of phenological change, local indicators for recognizing these changes, and a willingness to abandon certain assumptions as needed in response to changes. This paper suggests that TEK plays an important role in socioecological resilience, because it encourages indigenous people's sensitivity to change and provides an adaptable knowledge system with a strong ecocentric view of nature that can support adjustments and that is flexible enough to accommodate the adjustments needed to respond to changes. The findings of this paper highlight the important role of TEK in fragile ecosystems under global climate change.

Strong ethics and flexible actions, the properties of traditional ecological knowledge (TEK), as key resources for socioecological resilience to the impacts of climate change: a case study of Baojiatun, Yunnan-Guizhou Plateau karst area, southwest China

\n For the problem of low horizontal resolution in the method of surface wave dispersion analysis, we apply the SH- and Love-wave full-waveforms to achieve 2D and 3D imaging of the subsurface. The gradient obtained by classical full-waveform inversion (FWI) is not scaled with increasing depth. The limited source frequency band, the non-uniform coverage between shot and geophone positions and double scattering are the main reasons for the phenomenon. The Hessian operator of the misfit function can clearly predict the inherent defocusing phenomenon and the artefacts generated by the double scattering in the gradient vector, and the inverse Hessian operator is used as a deconvolution operator to realise gradient preconditioning. We present an expression of the quasi-Hessian operator in SH- and Love-wave FWI based on inverse scattering theory in prestack depth migration, and apply a new preconditioned technique to the fault and large contrast (LC) model reconstruction test. The inverted results show that the new preconditioned technique can greatly improve the imaging accuracy compared with the gradient-based methods of FWI. From single-parameter tests, we can conclude that the quasi-Hessian operator plays roles in illumination compensation and parameter complement estimation in FWI. From the final reconstructed results of a dual-parameter model, we find that the inverted result of the density is slightly closer to the true model than S-wave velocity under the condition of the same comparative distance between the initial and true model, but parametric crosstalk of density is more serious.

A preconditioned technique for SH- and Love-wave full-waveform inversion in time domain and crosstalk analysis

GPR signal is essentially a delayed, scaled and distorted version of the transmitted pulse, determined by sparse parameters such as time delays and amplitudes. The time delay indicates the detected target's depth, and the amplitude is the impedance contrast at interface or reflection coefficient. A system for sampling GPR signal at an ultra-low sampling rate based on the Finite Rate of Innovation (FRI) and the estimation of time delays and amplitudes to detect GPR signal is presented in the paper. We build the algorithm and apply it to real GPR data from Northwest of China. The results demonstrate that the inverted impedance and time delay can be used to depict the sandstone and clay layer with high accuracy.

http://ieeexplore.ieee.org/iel7/6962870/6970371/06970482.pdf

Jing Li

Papers

Strong ethics and flexible actions, the properties of traditional ecological knowledge (TEK), as key resources for socioecological resilience to the impacts of climate change: a case study of Baojiatun, Yunnan-Guizhou Plateau karst area, southwest China

A preconditioned technique for SH- and Love-wave full-waveform inversion in time domain and crosstalk analysis

The inversion GPR signal by compressing sensing and its application

New Interferometric Imaging Methods: Parsimonious Interferometry and Supervirtual Interferometry+Tomography for Far-Offset Refractions

High resolution wave-equation traveltime inversion utilizing the first arriving signals