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41.
High-resolution geoacoustic inversion in shallow water: a joint time- and frequency-domain technique
High-resolution geoacoustic data are required for accurate predictions of acoustic propagation and scattering in shallow water. Since direct measurement of geoacoustic data is difficult, time-consuming, and expensive, inversion of acoustic data is a promising alternative. However, the main problem encountered in geoacoustic inversion is the problem of uniqueness, i.e., many diverse geoacoustic models can be made to fit the same data set. A key, and perhaps unique, aspect of this approach is the combination of data analysis in both the space-time and the space-frequency domains. This combination attempts to ameliorate the uniqueness problem by exploiting as much independent data as possible. In order to meet the stringent requirements of high spatial resolution and uniqueness, an entire method has been developed including a new measurement technique, processing/analysis technique, and inversion strategy. These techniques are described and then illustrated with a shallow-water data set. Sound-speed gradients in the upper few meters of the sub-bottom appear to be much higher (one order of magnitude) than generally assumed. And, although often ignored, a large density gradient was observed in the top layer that played an acoustically significant role. 相似文献
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E. Cohen J. W. Commelin Pfeffer van 't Hoff Ladenburg Adie Tammann Raoult Naccari Ponsot H. N. Morse D. W. Horn J. C. W. Frazer B. S. Hopkins E. J. Hoffmann W. L. Kennon L. F. Lovelace W. W. Holland F. M. Rogers P. B. Dunbar B. Mears B. F. Lovelace Berkeley Hartley Barlow und L. Kahlenberg 《Fresenius' Journal of Analytical Chemistry》1909,48(4-5):273-278
Ohne Zusammenfassung 相似文献
45.
Letm(t)dt be a positive measure onR
+. We investigate the relations among the growth ofm, the growth of its moment sequence {yn}, the growth of its Bergman kernel functionk
x=Σγ{n/-1}x
n, and the growth of the kernel function associated to the measureK(t)
−1m(t) dt. For a large class of measures, we find that these quantities satisfy asymptotic relations similar to the simple exact
relations which hold in the model casem(t)=e
−1.
Supported in part by a grant from the National Science Foundation. 相似文献
46.
An investigation on thin Ta2O5 films patterning using argon ion beam etching (IBE) is presented. The etch rates are characterised by varying the angle of incidence of the beam onto the substrate. Ta2O5 gratings with a period of 2.2 μm (1.1 μm linewidth) and 0.25 μm thickness are fabricated using an angle of incidence of 0°. The resulting Ta2O5 grating cross sectional profiles are analysed using AFM and SEM imaging. A fabrication method is thus demonstrated which could be used to implement wavelength selective gratings in applications such as grating-assisted directional couplers (GADCs). 相似文献
47.
Herbert L. Holland Peter R. Andreana Reza Salehzadeh-Asl Aaron van Vliet Nancy J. Ihasz Frances M. Brown 《Monatshefte für Chemie / Chemical Monthly》2000,40(5):667-672
Biotransformation of a series of racemic N-benzoyl α-amino acids by the fungus Beauveria bassiana ATCC 7159 results in isolation of the corresponding D-amino acid benzamides in high enantiomeric purity and yield. 相似文献
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Jagdeep S. Sagu K.G. Upul Wijayantha Paul Holland Mallika Bohm Siva Bohm Tapan Kumar Rout Hemaka Bandulasena 《Crystal Research and Technology》2016,51(8):466-474
Carbon emissions from industrial sources are of major global concern, especially contributions from the steel manufacturing process which accounts for the majority of emissions. Typical blast furnace gases consist of CO2 (20‐25%), CO (20‐25%), H2 (3‐5%) and N2 (40‐50%) and trace amounts of other gases. It is demonstrated that gas mixtures with these compositions can be used at atmospheric pressure to grow carbon nanotubes (CNTs) by chemical vapor deposition (CVD) on to steel substrates, which act as catalysts for CNT growth. Computational modelling was used to investigate the CNT growth conditions inside the CVD chamber. The results show that industrial waste pollutant gases can be used to manufacture materials with significant commercial value, in this case CNTs. 相似文献
50.
The new ligand cis,cis-1,3,5-tris-(E)-(tolylideneimino)cyclohexane (TACH-o-tolyl) forms a 1:1 complex with iron(II). Addition of substituted phenolates forms 1:1:1 ligand:iron:phenolate complexes, which have been characterized both in the solid state and in solution. There is complete binding of the phenolate to the complex only when there are ortho-halogens on the phenolate. The tertiary complexes with ortho-halo-substituted phenolates exhibit short Fe-halogen distances, and the complex containing a non-coordinating but similarly sized ortho-methyl phenolate has a significantly different conformation and coordination geometry. Therefore, it is likely that the metal-halogen interaction stabilizes the complexes. The iron(II)-halogen interaction in these complexes may explain the substrate specificity of PcpA and LinE, enzymes that preferentially bind phenols and hydroquinones containing halogen substituents in ortho positions. 相似文献