http://www.users.abo.fi/jwerkeli/OOK%20I%202010/Jaworek%3B%20Modern%20electrostatic%20devices%20and%20methods%20for%20exhaust%20gas%20cleaning.pdf

Modern electrostatic devices and methods for exhaust gas cleaning: A brief review

Computerized tomography (CT) techniques can be used to produce a two-dimensional image of the electron density in the ionosphere. The CT problem requires that the measured data be the line integral through the medium of the unknown parameter; transionospheric satellite beacon total electron content data recorded simultaneously at multiple ground stations fulfill this requirement. In this paper the CT problem is formulated as it applies to ionospheric imaging and limitations of the technique are investigated. Simulations are performed assuming a 1000-km-altitude polar-orbiting satellite and both five and three ground stations; the results demonstrate the feasibility of this technique. 14 references.

Ionospheric imaging using computerized tomography

Nowadays, an increasing attention has been paid to the technologies for removing mercury from flue gases. Up to date, no optimal technology that can be broadly applied exists, but the heterogeneous catalytic oxidation of mercury is considered as a promising approach. Based on a brief introduction of the pros and cons of traditional existing technologies, a critical review on the recent advances in heterogeneous catalytic oxidation of elemental mercury is provided. In this contribution, four types of Hg oxidation catalysts including noble metals, selective catalytic reduction (SCR) catalysts, transition metals, and fly ash have been summarized. Both the advantages and disadvantages of these catalysts are described in detail. The influence of various acidic gases including SO2, SO3, NH3, NOx, HCl, Cl2, etc. have been discussed as well. We expect this work will shed light on the development of heterogeneous catalytic oxidation of elemental mercury technology in flue gases, particularly the synthesis of novel...

A Critical Review on the Heterogeneous Catalytic Oxidation of Elemental Mercury in Flue Gases

Two-stage electrostatic precipitators for the reduction of PM2.5 particle emission

Summary

An iterative tomographic inversion scheme is presented for determination of 2-D velocity structure from seismic refraction first-arrival traveltimes. the method is suited to refraction profiles where source/receiver spacings are denser than for conventional profiles. the inversion method is based on an iterative solution of the linearized problem, and allows for determination of continuous velocity variations as welt as geometry of subhorizontal interfaces. In each iteration, two-point ray tracing is performed using a shooting method to construct the linear system. the velocity field is defined using triangular cells within which the velocity gradient is constant, allowing analytic calculation of ray paths. Two different inversion techniques are considered, based on distinct linearized formulations of the forward problem. Inversion using a linearized traveltime-velocity Jacobian produced better results than a slowness formulation more akin to common series expansion-techniques. Resolution examples reveal horizontal smearing due to ray geometry, drop-off in resolution with depth, as well as the effect of source-receiver geometry and velocity structure on resolution. Inversion examples indicate that a global norm produces solutions closer to the true model than solutions calculated using a smallest perturbation approach, when a good starting model is available. Streak effects caused by inhomogeneous ray coverage and the removal of these effects are demonstrated.

Two-Dimensional Seismic Refraction Tomography

Membrane-based wet electrostatic precipitation

A geometrical optics model for propagation in conducting media requires the determination of the propagation constants for the field transmitted through a plane boundary. In general, the transmitted fiJeld produced by a nonuniform plane wave incident upon a plane boundary between two conducting media propagates with constants which are different from the intrinsic constants of the medium. The expressions for these constants are derived, and data are presented to illustrate when these modified propagation constants must be used to yield valid results.

Modified Propagation Constants for Nonuniform Plane Wave Transmission through Conducting Media

Remote determination of underground geophysical structures is a matter of considerable interest. Detecting such structures by scanning the area of interest with electromagnetic radiation is shown to reduce to the problem of solving an inconsistent system of equations for a spatial attenuation distribution. This paper examines the employment of reconstruction algorithms to solve such systems of equations, and it presents significant modifications to a standard algorithm that vastly improves its performance in the presence of noisy data. The process of in situ coal gasification is taken as an example to illustrate the superior performance of the modified algorithm.

Reconstruction algorithms for geophysical applications in noisy environments

The application of tomographical techniques to geophysical monitoring and exploration has been extended to media where refraction and reflection effects may be significant. The result is an iterative refinement scheme which is unstable in its original formulation. This paper presents the stability improvements of selective smoothing and path elimination which enable the reconstruction process to converge to an accurate solution. By use of the objective error measures of Euclidean distance and boundary definition by minimum variance partitioning, tomograms produced by this improved technique are shown to be superior to those obtained by traditional straight-line geotomography. Guidelines for practical application are presented.

A stable geotomography technique for refractive media

An accurate technique for remotely determining the internal structure of an object or underground environment would have a significant impact in mining, geoexploration, ultrasonics, and the life sciences. This process of resolving the intrinsic properties of an object or environment by the transmission of radiation or ultrasound through the unknown anomaly is known as reconstructive imaging or tomography. Several efforts have been made to apply imaging (reconstruction) methods to measurements taken between two boreholes on either side of an unknown geophysical structure. However, it became necessary, because of the nature of existing reconstruction methods, to assume a straight-line propagation path from source to receiver. This assumption is not valid in many important applications of geophysical imaging; thus it is desirable to develop a method to account for the radiation mechanisms of refraction and reflection in the unknown medium. An imaging scheme that explicitly incorporates refraction and first-order reflection in the reconstruction process is developed. Several examples of successful reconstruction of multicell underground environments are presented to demonstrate its accuracy.

R. Radcliff

Papers

Membrane-based wet electrostatic precipitation

Modified Propagation Constants for Nonuniform Plane Wave Transmission through Conducting Media

Reconstruction algorithms for geophysical applications in noisy environments

A stable geotomography technique for refractive media

Electromagnetic geophysical imaging incorporating refraction and reflection