ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Marine Geosciences and Applied Geophysics  (2)
  • canopy  (2)
  • 2015-2019  (4)
  • 1975-1979
  • 1950-1954
  • 1
    Publication Date: 2015-11-07
    Description: Many birds in breeding seasons engage in vigorous dawn singing that often turns to a prominent chorus. We examined dawn chorus variation of avian assemblages in a tropical montane forest in Taiwan and tested the hypothesis that onset sequence is affected by eye sizes, foraging heights, and diet of birds. Chorus onset and duration varied between sampling months, but generally peaked in the prime breeding season. Overall dawn chorus length increased with, but mean duration per species was negatively correlated with, species richness. The inter-correlation among trait variables in phylogenetic independent contrasts was calculated and examined. Both foraging height and relative eye size were selected as positively explanatory factors, but no dietary effects were detected, for chorus onsets. Dawn singing onsets also tended to delay as decreasing log (eye sizes) that, however, was not selected with enough explanatory power. The positive relationship of chorus onsets versus relative eye sizes contradicts our prediction, yet the negative correlation of relative eye sizes with log (eye sizes) indicates an allometric constraint on eye sizes along with increasing body sizes. Lowerlayer species initiated singing earlier than upper-layer species, which complies with the positive correlation of onsets with foraging heights and supports our prediction. This pattern may be condition-specific and more likely occurs in forests lacking a sufficient canopy height and layering and a distinct light difference among forest layers. Foraging heights were additionally found negatively correlated with canopy coverage and slightly positively correlated with ground coverage of perches. Our results concord that foraging height is a relevant factor as eye size in determining the onset and sequence of dawn chorus, yet, suggest that forest settings and vegetation structure may likely complicate the prediction.
    Keywords: breeding ; canopy ; diets ; eye size ; foraging ; perch ; Taiwan ; tropical forests ; birds ; 42.83 ; 42.62
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2024-01-12
    Description: Many birds in breeding seasons engage in vigorous dawn singing that often turns to a prominent chorus. We examined dawn chorus variation of avian assemblages in a tropical montane forest in Taiwan and tested the hypothesis that onset sequence is affected by eye sizes, foraging heights, and diet of birds. Chorus onset and duration varied between sampling months, but generally peaked in the prime breeding season. Overall dawn chorus length increased with, but mean duration per species was negatively correlated with, species richness. The inter-correlation among trait variables in phylogenetic independent contrasts was calculated and examined. Both foraging height and relative eye size were selected as positively explanatory factors, but no dietary effects were detected, for chorus onsets. Dawn singing onsets also tended to delay as decreasing log (eye sizes) that, however, was not selected with enough explanatory power. The positive relationship of chorus onsets versus relative eye sizes contradicts our prediction, yet the negative correlation of relative eye sizes with log (eye sizes) indicates an allometric constraint on eye sizes along with increasing body sizes. Lowerlayer species initiated singing earlier than upper-layer species, which complies with the positive correlation of onsets with foraging heights and supports our prediction. This pattern may be condition-specific and more likely occurs in forests lacking a sufficient canopy height and layering and a distinct light difference among forest layers. Foraging heights were additionally found negatively correlated with canopy coverage and slightly positively correlated with ground coverage of perches. Our results concord that foraging height is a relevant factor as eye size in determining the onset and sequence of dawn chorus, yet, suggest that forest settings and vegetation structure may likely complicate the prediction.
    Keywords: breeding ; canopy ; diets ; eye size ; foraging ; perch ; Taiwan ; tropical forests ; birds
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2016-05-22
    Description: The seislet transform has been demonstrated to have a better compression performance for seismic data compared with other well-known sparsity promoting transforms, thus it can be used to remove random noise by simply applying a thresholding operator in the seislet domain. Since the seislet transform compresses the seismic data along the local structures, the seislet thresholding can be viewed as a simple structural filtering approach. Because of the dependence on a precise local slope estimation, the seislet transform usually suffers from low compression ratio and high reconstruction error for seismic profiles that have dip conflicts. In order to remove the limitation of seislet thresholding in dealing with conflicting-dip data, I propose a dip-separated filtering strategy. In this method, I first use an adaptive empirical mode decomposition based dip filter to separate the seismic data into several dip bands (5 or 6). Next, I apply seislet thresholding to each separated dip component to remove random noise. Then I combine all the denoised components to form the final denoised data. Compared with other dip filters, the empirical mode decomposition based dip filter is data-adaptive. One only needs to specify the number of dip components to be separated. Both complicated synthetic and field data examples show superior performance of my proposed approach than the traditional alternatives. The dip-separated structural filtering is not limited to seislet thresholding, and can also be extended to all those methods that require slope information.
    Keywords: Marine Geosciences and Applied Geophysics
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2016-10-09
    Description: Full waveform inversion (FWI) is a promising technique for inverting a high-resolution subsurface velocity model. The success of FWI highly depends on a fairly well initial velocity model. We propose a method for building a good initial velocity model that can be put into the FWI framework for inverting a nearly perfect velocity structure. We use a well log interpolated velocity model as a high-fidelity initial model for the subsequent FWI. The interpolation problem is solved via a least-squares method with a geological structural regularization. In order to obtain the geological structure of subsurface reflectors, an initial reverse time migration (RTM) with a fairly realistic initial velocity model is conducted, and the local slope of subsurface structure is roughly calculated from the RTM image. The well log interpolated initial velocity model can be very close to the true velocity while containing a small velocity anomaly or oversmoothing caused by the imperfect velocity interpolation. The anomaly and oversmoothing effect can be compensated during the subsequent FWI iterations. We use a relatively simple-layered model and the more complicated Marmousi velocity model to demonstrate the applicability of the proposed approach. We start from a very smooth velocity model and obtain a nearly perfect FWI result which is much better than the traditional FWI result without the velocity interpolation. The migrated images from the RTM method using different velocity models are also compared to further confirm the effectiveness of the proposed framework. Regarding the field deployment, we suggest that future drilling of exploration wells can be seismic-oriented, which can help fully utilize the information of well logs for building initial subsurface velocity model and will facilitate a wide application of the proposed methodology.
    Keywords: Marine Geosciences and Applied Geophysics
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...