10,788 research outputs found
Near-Surface Model Prediction and Refinement by Full Waveform Surface Wave Inversion
No full textGenetic algorithm full waveform inversion (GA-FWI) is able to predict complex shear-wave velocity (Vs) models fairly from surface waves, even in the case when very limited or null a-priori information is available (Xing and Mazzotti, 2017a). Out of consideration for computing time reduction, a two-grid approach (Sajeva et al., 2016; Aleardi and Mazzotti, 2017; Mazzotti et al., 2017), one coarse grid for the inversion and one small grid for the modeling, is recommended for the method. Thus, we generally obtain smooth velocity models whose wavelengths are dependent on the coarse grid spacing. In this paper, we show that these models are suitable starting models for FWI approaches with local optimization methods and that, in general, significant details of the depth model can be retrieved. Instead, we do not discuss the influences caused by different surface wave modeling strategies (Thorbecke and Draganov, 2011; Groos, 2013; Xing and Mazzotti, 2016) and by assumptions in wave modeling (Xing and Mazzotti, 2017b), thus we focus on model prediction and refinement
Bambusananus yangae Xing & Chen 2013, nom. nov.
No full text<i>Bambusananus yangae</i> Xing & Chen, nom. nov. <p> <i>Bambusananus yangae</i>, <i>nomen novum</i> for <i>Bambusananus lii</i> Yang & Chen, 2012: 50, preoccupied by <i>Bambusananus lii</i> (McKamey & Hicks, 2007)</p> <p> The new name is based on the surname of the first author of the junior homonym. Accordingly, the genus <i>Bambusananus</i> currently includes the following species: <i>Bambusananus maculipennis</i> (Li & Wang, 1993), <i>Bambusananus bipunctatus</i> (Li, 1999), <i>Bambusananus lii</i> (McKamey & Hicks, 2007), <i>Bambusananus furcatus</i> Li & Xing, 2011 and <i>Bambusananus yangae</i> Xing & Chen, <b>nom. nov.</b>.</p>Published as part of <i>Xing, Ji-Chun & Chen, Xiang-Sheng, 2013, Nomenclatural changes in the genus Bambusananus Li & Xing, 2011 (Hemiptera: Cicadellidae: Deltocephalinae: Athysanini), pp. 599-600 in Zootaxa 3635 (5)</i> on page 599, DOI: 10.11646/zootaxa.3635.5.12, <a href="http://zenodo.org/record/5262395">http://zenodo.org/record/5262395</a>
Surface Wave FWI on Complex Models - The Robustness of the Inversion to Assumptions and Forward Modeling Approximations
No full textFull waveform inversion (FWI) of surface waves with genetic algorithm (GA) is able to invert complex near surface models even in the case where very limited a-priori information is available, but it requires long computing time. One way to reduce the computing time is to make assumptions on the subsurface and to simplify the forward modelling. By using a few complex near surface models, with velocity inversions, lateral velocity variations and with an irregular topographic surface, we discuss how the following issues affect the inversion results in terms of either the data misfit or the model misfit: 1) fixing the compressional wave velocities and densities to the estimated shear wave velocities according to empirical equations, instead of inverting them; 2) neglecting attenuation in the forward modelling; 3) performing 2D forward modelling and applying a 3D to 2D correction to the observed data. Although these approximations degrade model prediction, yet the main features of the shear wave models can be retrieved. Instead, the data prediction is always satisfactory, showing again that theoretical approximations in the forward modelling affect more the model misfit than the data misfit
Two-grid Full Waveform Rayleigh Wave Inversion by Means of Genetic Algorithm with Frequency Marching
No full textWe present a 2D elastic full waveform inversion (FWI) of Rayleigh waves (RW) with a genetic algorithm (GA) as the optimization tool and with a finite difference code as the forward modeling engine. To limit the computing time required by GA, we implement the RW FWI, making use of a two-grid parametrization of the subsurface model, one fine grid and one coarse grid, and of frequency marching during the evolution of the GA optimization. Forward modeling is performed on the fine grid to avoid numerical dispersion, while the GA inverts for the unknown velocities and densities at the nodes of the coarse grid. The coarser the grid the less the unknowns to be inverted for, at the expense of the final model resolution. Frequency marching also speeds up convergence because it has the ability of rejecting unrealistic models at the initial generations of the GA. Due to the very band-limited nature of RW, we suggest to start frequency marching from near the peak frequency of RW. Synthetic examples reproducing velocity inversions, lateral velocity variations and varying elevations show the feasibility of the proposed RW FWI, without any a-priori information and with shear-wave and
compressional-wave velocities and densities as unknowns
Vrsanskysajda Jiang, Xing & Li, 2023, nom. nov.
No full textGenus Vrsanskysajda nom. nov. Sajda Vršanský, 2021: 27 (Blattaria: Corydiidae: Holocompsinae). Preoccupied by Sajda Dworakowska, 1981: 244 (Homoptera: Cicadellidae: Typhlocybinae). Type species: Vrsanskysajda equatorialis (Vršanský in Vršanský et al. 2021) comb. nov. Etymology. The replacement name for the genus is derived from the name of Peter Vršanský, the author of the genus Sajda. Gender: feminine. Distribution. Brezina, Algeria.Published as part of Jiang, Lina, Xing, Jichun & Li, Yujian, 2023, New replacement name for the genus Sajda Vršanský, 2021 (Blattaria: Corydiidae: Holocompsinae), pp. 343-344 in Zootaxa 5270 (2) on page 343, DOI: 10.11646/zootaxa.5270.2.10, http://zenodo.org/record/784970
Matsumuramata Xing & Chen, 2014, nom. nov.
No full textGenus Matsumuramata nom. nov. Numata Matsumura, 1935: 139 (Hemiptera: Fulgoromorpha: Delphacidae). Preoccupied by Numata Busck, 1906: 724 (Lepidoptera: Gelechioidea: Gelechiidae). Type species: Stenocranus sacchari Matsumura, 1910 Etymology. The generic name is dedicated to Prof. Shōnen Matsumura who is the author of the preexisting generic name Numata. Gender: feminine.Published as part of Xing, Ji-Chun & Chen, Xiang-Sheng, 2014, Nomenclatural changes for the genus Discophorellus Tsaur & Hsu, 1991 and new replacement name for Numata Matsumura, 1935 (Hemiptera: Fulgoromorpha), pp. 149-150 in Zootaxa 3856 (1) on page 150, DOI: 10.11646/zootaxa.3856.1.8, http://zenodo.org/record/492985
Two-Grid Genetic Algorithm Full Waveform Inversion of Surface Waves: Two Actual Data Examples
No full textWe present the application to two field data cases of our two-grid full waveform inversion (FWI) of surface waves for the prediction of 2-D shear-wave velocity models. The inversion employs a genetic algorithm as the optimization tool and a finite difference forward modeling. We aim at estimating models reproducing the long-wavelength structures of the velocity field. Frequency marching up to 30 Hz is included in the inversion. The use of a global optimization method allows us to relax the requirement of local optimization methods of having a “good” starting model from which to launch the inversion. In fact, we show that fair results can be retrieved even in the case of null a-priori information. In the first example, we find a satisfactory matching between the predicted model and the long-wavelength velocity structure exhibited by velocity logs from nearby boreholes. The predicted seismograms match well the observed data and when mismatches occur, the time shifts are within half-periods. In the second example, the inversion well predicts the fundamental mode and partially predicts the 1st higher mode. The fair inversion results indicate that the models derived from our stochastic approach could be proper initial models for a local optimization FWI
Foreign direct investment and China's bilateral intra-industry trade with Japan and the US
No full textThis paper analyzes dynamic changes of China's intra-industry trade with its major trading partners, Japan and the US, from 1980 to 2004. It also investigates to what extent foreign direct investment promoted intra-industry trade. The empirical results show that, while shares of China's intra-industry trade with both Japan and U.S rose substantially, its intra-industry trade with Japan has reached 35 per cent of the overall trade, considerably larger than 10 per cent with the US. Sino-Japan intra-industry trade concentrated in the electrical and machinery sectors accounted for 52 per cent and 46 per cent of overall trade respectively. On the other hand, it is in the chemical and food sectors where intra-industry trade represented a relatively large proportion of Sino-US trade, 50 per cent and 30 per cent accordingly in each sector. In addition, the analysis indicates that Japanese direct investment in China performed a significant role in enhancing intra-industry trade between Japan and China. However, it found no evidence that the US direct investment in China contributed to the growth of the bilateral intra-industry trade between the two countries.intra-industry trade; FDI; China
Field examples and numerical modelling of oversteps and bends along normal faults in cross-section
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