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Verhoef, W. (author)
In the past, a relatively simple radiative transfer model, based on scattering and extinction of two semi-isotropic diffuse fluxes and two direct fluxes (solar beam and radiance in the viewing direction), has been applied to vegetation canopies and to the atmosphere. This model takes little computing power, but its numerical accuracy had not yet...
report 1988
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Blok, H. (author), Fokkema, J.T. (author), De Hoop, A.T. (author)
book 1996
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Stowers, M.A. (author), Van Wuijckhuijse, A.L. (author), Marijnissen, J.C.M. (author), Kientz, C.E. (author), Ciach, T. (author)
We have designed, constructed, and tested a system that preselects the biological fraction of airborne particles from the overall aerosol. The preselection is based on fluorescence emission excited by a continuous 266 nm laser beam. This beam is one of two cw beams used to measure the aerodynamic particle size of sampled particles. The intention...
journal article 2006
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Turkel, E. (author), Erlangga, Y.A. (author)
We consider acoustic scattering about a general body. This is described by the Helmholtz equation exterior to the body. In order to truncate the infinite domain we use the BGT absorbing boundary condition. The resultant problem in a finite domain is solved by a finite element procedure. This yields a large sparse system of linear equations which...
conference paper 2006
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Gerritsen, S. (author)
In this thesis we study wave propagation in inhomogeneous media. Examples of the classical (massless) waves we consider are acoustic waves (sound) and electromagnetic waves (light, for example). Interaction with inhomogeneities embedded in a reference medium alter the propagation direction, velocity and amplitude of waves. We describe the...
doctoral thesis 2007
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Simons, D.G. (author), Snellen, M. (author), Ainslie, M.A. (author)
Sound backscattered from the seabed has been measured in a 10x10-nmi2 region of the North Sea, characterized by a variety of bottom types, including mud, sand, and gravel. The backscattering strength measurements are made by a forward- looking sonar, operating at 100 kHz and tilted at an angle of 30 from the horizontal. Fifty bottom-grab samples...
journal article 2007
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Testa, C. (author)
doctoral thesis 2008
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Dietrich, H.R.C. (author), Rieger, B. (author), Wiertz, F.G.M. (author), De Groote, F.H. (author), Heering, H.A. (author), Young, I.T. (author), Garini, Y. (author)
journal article 2009
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Hörchens, L. (author)
The detection of inhomogeneities in plates or plate-like structures constitutes a major problem in the field of non-destructive testing. For a few decades, classical techniques based on X-ray radiography have - as far as possible - been complemented and replaced by the usage of vibrations or acoustical waves due to the fact that these are less...
doctoral thesis 2010
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Demi, L. (author)
The design and optimization of medical ultrasound modalities require a method for modeling the propagation of pressure wave fields through biomedical tissue. This method needs to be capable of modeling various phenomena, e.g. nonlinear propagation, attenuation, and scattering caused by arbitrary inhomogeneities in the acoustic properties of the...
doctoral thesis 2013
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Konstantaki, L.A. (author), Dragnov, D.S. (author), Heimovaara, T.J. (author), Ghose, R. (author)
A significant problem with landfills is their aftercare period. A landfill is considered to be safe for the environment only after a relatively long period of time. Until it reaches such a condition, it has to be periodically treated. Not only are treatments very expensive, but they could be dangerous as well; for example, when barriers limiting...
journal article 2013
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Broggini, F. (author), Wapenaar, C.P.A. (author), Van der Neut, J.R. (author), Snieder, R. (author)
An iterative method is presented that allows one to retrieve the Green's function originating from a virtual source located inside a medium using reflection data measured only at the acquisition surface. In addition to the reflection response, an estimate of the travel times corresponding to the direct arrivals is required. However, no detailed...
journal article 2014
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Minato, S. (author), Ghose, R. (author)
Using the scattered elastic wavefield, a method to derive the power spectral density (PSD) of the heterogeneous compliance distribution, along the plane of a single fracture, is formulated. The method involves estimation of the stress field at the fracture depth from the scattered wavefield followed by least-squares optimization of the PSD of...
journal article 2014
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Molera Calvés, G. (author), Pogrebenko, S.V. (author), Cimò, G. (author), Duev, D.A. (author), Bocanegra-Bahamón, T.M. (author), Wagner, J.F. (author), Kallunki, J. (author), De Vicente, P. (author), Kronschnabl, G. (author), Haas, R. (author), Quick, J. (author), Maccaferri, G. (author), Colucci, G. (author), Wang, W.H. (author), Yang, W.J. (author), Hao, L.F. (author)
Aims. The phase scintillation of the European Space Agency’s Venus Express (VEX) spacecraft telemetry signal was observed at X-band (? = 3.6 cm) with a number of radio telescopes of the European Very Long Baseline Interferometry (VLBI) Network in the period 2009–2013. Methods. We found a phase fluctuation spectrum along the Venus orbit with a...
journal article 2014
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Nemati, M. (author), Presura, C.N. (author), Urbach, H.P. (author), Bhattacharya, N. (author)
Continuous health monitoring has become a major theme of our aging society. Portable devices play an important role here. Many optical portable devices are susceptible to motion induced artifacts. We have performed an experimental study for detection of fluid pulsation based on multi-exposure speckle images, in presence of motion induced...
journal article 2014
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Singh, S. (author), Snieder, R. (author), Behura, J. (author), van der Neut, J.R. (author), Wapenaar, C.P.A. (author), Slob, E.C. (author)
Recent work on autofocusing with the Marchenko equation has shown how the Green's function for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green's function from the location of the virtual source to the surface. The Green's function is retrieved using only the reflection...
conference paper 2014
document
Konstantaki, L.A. (author), Ghose, R. (author), Draganov, D.S. (author), Diaferia, G. (author), Heimovaara, T.J. (author)
Understanding the processes occurring inside a landfill is important for improving the treatment of landfills. Irrigation and recirculation of leachate are widely used in landfill treatments. Increasing the efficiency of such treatments requires a detailed understanding of the flow inside the landfill. The flow depends largely on the...
journal article 2014
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Minato, S. (author), Ghose, R. (author)
Fluid flow through a fractured reservoir is often controlled by the large fractures. Seismically imaging these large fractures has the potential to illuminate their hydraulic properties.We derived a nonlinear imaging condition considering a medium containing nonwelded interfaces such as fractures for high-resolution fracture imaging. This was...
journal article 2015
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Ozmen, N. (author), Dapp, R. (author), Zapf, M. (author), Gemmeke, H. (author), Ruiter, N.V. (author), Van Dongen, K.W.A. (author)
Ultrasound is frequently used to evaluate suspicious masses in breasts. These evaluations could be improved by taking advantage of advanced imaging algorithms, which become feasible for low frequencies if accurate knowledge about the phase and amplitude of the wave field illuminating the volume of interest is available. In this study, we compare...
journal article 2015
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Singh, S. (author), Snieder, R. (author), Behura, J. (author), van der Neut, J.R. (author), Wapenaar, C.P.A. (author), Slob, E.C. (author)
Recent work on retrieving the Green’s function with the Marchenko equation shows how these functions for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green’s function from the location of the virtual source to the surface. The Green’s function is retrieved using only the...
journal article 2015
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