Full waveform inversion (FWI) can generate high-resolution subsurface models, but often suffers from an objective function with local minima caused mainly by an absence of low frequencies in seismograms. These local minima cause cycle skipping when the initial model for FWI is far from the true model. To avoid cycle skipping, traveltime inversion is often used to compute initial models for FWI....

The magnetotelluric (MT) method has become more widely used in hydrocarbon exploration. The inversion of MT data, which can determine the electrical structure of subsurface, is a nonlinear and multimodal optimization problem. Particle swarm optimization(PSO) algorithm is a good solver for this geophysical inversion problem, whereas it has a shortage of heavy computation time. An improved parall...

an experimental study of the phase inversion behavior of liquid-liquid dispersion has been conducted in a spray extraction column for systems of toluene / water, n-hexane/water, ccl4/water, toluene /water + glycerol (25 % wt), toluene + ccl4 (25 % wt) / water and toluene / acetic acid (5 % wt)/water. the effects of physical properties, mass transfer and column geometry on phase inversion have b...

the source parameters and focal depth of the destructive mw 6.5, 31 march. 2006 iran- silakhor earthquake, the two largest foreshocks and a major aftershock are determined using broadband data from a seismic network in iran based on a time-domain linear moment tensor inversion. the earthquakes occurred in the zagros suture zone in western iran. waveform inversion of the selected events estimate...

This study deduces a general inversion of continuous wavelet transform (CWT) with timescale being real rather than positive. In conventional CWT inversion, wavelet’s dual is assumed to be a reconstruction wavelet or a localized function. This study finds that wavelet’s dual can be a harmonic which is not local. This finding leads to new CWT inversion formulas. It also justifies the concept of n...

The Inversion Algorithm is an event-driven algorithm, whose performance rivals or exceeds that of Levelized Compiled code simulation, even at activity rates of 50% or more. The Inversion Algorithm has several unique features, the most remarkable of which is the size of the run-time code. The basic Algorithm can be implemented using no more than a page of run-time code, although in practice it i...

PURPOSE Signal intensity and image contrast differ between postmortem magnetic resonance (PMMR) images and images acquired from the living body. We sought to achieve sufficient fat suppression with short-tau inversion recovery (STIR) PMMR imaging by optimizing inversion time (TI). MATERIAL AND METHODS We subjected 37 deceased adult patients to PMMR imaging at 1.5 tesla 8 to 60 hours after con...

Aims Data assimilation is a useful tool to extract information from large datasets of the net ecosystem exchange (NEE) of CO2 obtained by eddy-flux measurements. However, the number of parameters in ecosystem models that can be constrained by eddy-flux data is limited by conventional inverse analysis that estimates parameter values based on one-time inversion. This study aimed to improve data a...

We perform a two-dimensional inversion of f-mode travel times to determine near-surface solar flows. The inversion is based on optimally localized averaging of travel times. We use finite-wavelength travel-time sensitivity functions and a realistic model of the data errors. We find that it is possible to obtain a spatial resolution of 2 Mm. The error in the resulting flow estimate ultimately de...

seismic inversion is a method that extracts acoustic impedance data from the seismic traces. sourcewavelets are band-limited, and thus seismic traces do not contain low and high frequency information.therefore, there is a serious problem when the deterministic seismic inversion is applied to real dataand the result of deterministic inversion is smooth. low frequency component is obtained from w...