the s-transform has widely been used in the analysis of non-stationary time series. a simple method to obtain depth estimates of gravity field sources is introduced in this study. we have developed a new method based on the spectral characteristics of downward continuation to estimate depth of structures. this calculation procedure is based on replacement of the fourier transform with the s-tra...

Background: In radiotherapy, low-energy photon beams are better adapted to the treated volume, and the use of high-energy beams can reduce hot spots in the radiation therapy. Therefore, mixing low and high energies with different ratios can control the rate of hotspots, as well as the dose distribution of the target volume.Material and Methods: The percentage depth doses (PDDs) were calculated ...

A simple model for predicting the velocities under breaking waves in depth-integrated models is developed. A velocity modification due to wave breaking is formulated based on a specific exponential profile, which is then added to the numerically predicted, depth-integrated velocity profile. This modification is superficial in that it does not directly change the hydrodynamic calculations inside...

introduction radiotherapy planning systems require many percentage depth dose (pdd) and profile measurements and there are various dosimeters that can be used to obtain these scans. as dose perturbation is particularly troublesome in smaller photon fields, using a low-perturbation, unshielded electron field diode (efd) in these fields is of interest. the aim of this work was to investigate the ...

In Aldous and Shields (1988), a model for a rooted, growing random binary tree was presented. For some c > 0, an external vertex splits at rate c−i (and becomes internal) if its distance from the root (depth) is i. For c > 1, we reanalyse the tree profile, i.e. the numbers of external vertices in depth i = 1, 2, .... Our main result are concrete formulas for the expectation and covariance-struc...

Modelling of surface temperature change effect on temperature vs. depth and temperature-depth logs in Western Canada Sedimentary Basin show that SAT (surface air temperature) forcing is the main driving factor for the underground temperature changes diffusing with depth. It supports the validity of the basic hypothesis of borehole temperature paleoclimatology, namely that the ground surface tem...

Accelerator mass spectrometry measures the depth profiles of material concentration in solid samples. Crater edge effects affect the experimental data when the secondary ions are sputtered from the sidewalls of the produced crater. We present a simple mathematical unfolding procedure that removes the perturbing contribution from the measured depth profile data. Application of this procedure to ...

The goal of this paper is to present a logic-based formalism for representing knowledge about objects in space and their movements, and show how this knowledge could be built up from the viewpoint of an observer immersed in a dynamic world. In this paper space is represented using functions that extract attributes of depth, size and distance from snapshots of the world. These attributes compose...

This paper develops an efficient three-dimensional localization method for transient acoustic sources, with uncertainty estimation, based on time differences between direct and surface-reflected arrivals at two hydrophones. The localization method accounts for refraction caused by a depth-dependent sound-speed profile using a ray-theoretic approach for calculating eigenray travel times and part...

We study the asymptotic behavior of solutions to fully nonlinear second order parabolic equations including a generalized curvature flow equation which was introduced by Mullins in 1957 as a model of evaporationcondensation. We prove that, in the multi-dimensional half space, solutions of the problem with prescribed contact angle asymptotically converge to a selfsimilar solution of the associat...