The calculation of the discharge to a constant drawdown well or tunnel in the presence of an infinite linear constant head boundary in an ideal confined aquifer usually relies on the numerical inversion of a Laplace transform solution. Such a solution is used to interpret constant head tests in wells or to roughly estimate ground water inflow into tunnels. In this paper, a simple approximate so...

Belief propagation (BP) on cyclic graphs is an efficient algorithm for computing approximate marginal probability distributions over single nodes and neighboring nodes in the graph. However, it does not prescribe a way to compute joint distributions over pairs of distant nodes in the graph. In this article, we propose two new algorithms for approximating these pairwise probabilities, based on t...

In the title structure, C(7)H(9)N(3)O(2)·H(2)O, there are two formula units in the asymmetric unit. The mol-ecule is a zwitterion, containing a quaternary N atom and a deprotonated carboxyl group, with C-O distances in the range 1.256 (2)-1.266 (3) Å. The two independent mol-ecules form a hydrogen-bonded R(2) (2)(16) dimer about an approximate inversion center via N-H⋯O hydrogen bonds, with N⋯O...

We modify RTM to create an approximate inverse to the extended Born modeling operator in 2D. The derivation uses asymptotic ray theory and stationary phase principle, but the result applies directly to RTM. The inverse operator differs from the adjoint operator only by application of several explicit velocity-independent filters. This inverse operator, on the one hand, can be used as true ampli...

The title compound, (CH(6)N(3))(5)[H(2)PtV(9)O(28)], containing the nona-vanadoplatinate(IV) polyanion, was obtained by hydro-thermal reaction. The polyanion has approximate C(2v) symmetry. The two Pt-bound μ(2)-O atoms are protonated in the polyanion. The heteropolyanions form inversion-generated dimers, {[H(2)PtV(9)O(28)](2)}(10-), held together by each of the two μ(2)-O-H⋯μ(2)-O and μ(2)-O-H...

The Mn(III) atom in the title complex, [Mn(C(18)H(18)N(2)O(4))(CHO(2))(H(2)O)]·2H(2)O, is O,N,N',O'-chelated by the deproton-ated Schiff base; the four chelating atoms form an approximate square, with the O atoms of the water mol-ecule and the formate ion in axial positions above and below the square plane. Two metal-bearing mol-ecules are linked by an O-H(water)⋯O hydrogen bond about a center ...

The title compound, C(17)H(16)N(4)O(6), is a Schiff base, which is found as a bis-zwitterion in the solid state. The geometry around the iminium N atom indicates sp(2)-hybridization. The diiminiumpropyl-ene chain is in an approximate double-gauche conformation, with average N-C-C-C torsion angles of 69.3°. The zwitterion shows strong intra-molecular N-H⋯O hydrogen bonds between the iminium N an...

There are one and a half independent mol-ecules in the asymmetric unit of the title compound, [Ni(C(8)H(8)NO)(2)], one of which is situated on an inversion center. In both mol-ecules, the Ni(II) ion is coordinated by two O and two N atoms from two Schiff base ligands in an approximate square-planar geometry. Inter-molecular N-H⋯O hydrogen bonds link three mol-ecules into centrosymmetric trimer....

Inversion of seismic AVO-data is an important part of reservoir evaluation. These data are convolved but the convolution kernel and the associated errorvariances are largely unknown. We aim at estimating these model parameters without using calibration observations in wells. This constitutes the first step in socalled blind deconvolution. We solve the seismic inverse problem in a Bayesian setti...

We consider the inversion of a linear operator with centered Gaussian white noise by MAP estimation with a Gaussian prior distribution on the solution. The actual estimator is computed approximately by a numerical method. We propose a relation between the stationarity measure of this approximate solution to the mean square error of the exact solution. This relation enables the formulation of a ...