Gas-water stratified flow patterns from electromagnetic tomography

Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomography can identify the flow patterns of mixed fluid from the different electrical properties of gas and water. The responses for different gas-water interface locations were calculated and then physical measurements were undertaken. We compared the results of the numerical simulation with the experimental data, and found that the response characteristics were consistent in the circumstances of uniform physical fields and stratified flows. By analyzing the signal characteristics, it is found that, with the change of the interface location, the response curves showed ＂steps＂ whose position and width were decided by the location of fluid interface. The measurement accuracy of this method depended on the vertical distance between adjacent electrodes. The results showed that computer simulation can simulate the measurement of the electromagnetic tomography accurately, so the physical experiment can be replaced.

Simulation Experiments in Electromagnetic Tomography Well Logging in Two-phase Flow

Electromagnetic Computer Tomography （ECT） is a method to probe the interior of an inhomogeneous medium via surface measurement in a non-linear way. Due to the great differences in conductivity and permittivity between oil and water in the well, Electromagnetic Tomography Well Logging （ETWL）, a new flow imaging measurement system, is proposed to describe the distribution and movement of oil/water two-phase flow in the well by scanning the detected region and applying a suitable data processing algorithm. The results of the numerical simulation and physical modeling show that the system could provide a clear image of the flow profile.

Electromagnetic Tomography System for Defect Detection of High-Speed Rail Wheel

A novel electromagnetic tomography(EMT)system for defect detection of high-speed rail wheel is proposed,which differs from traditional electromagnetic tomography systems in its spatial arrangements of coils.A U-shaped sensor array was designed,and then a simulation model was built with the low frequency electromagnetic simulation software.Three different algorithms were applied to perform image reconstruction,therefore the defects can be detected from the reconstructed images.Based on the simulation results,an experimental system was built and image reconstruction were performed with the measured data.The reconstructed images obtained both from numerical simulation and experimental system indicated the locations of the defects of the wheel,which verified the feasibility of the EMT system and revealed its good application prospect in the future.

Assessment of Stress Cognitive Control and Executive Function with Stress Control Rating Scale (ECOSTRESS) and Low Resolution Brain Electromagnetic Tomography (LORETA) (In Portuguese People in Situations of Unemployment and Economic Insufficiency)

This article reviews the constructs of stress, appraisal, coping, according to a transactional perspective, and executive function, and presents a stress control rating scale (ECOSTRESS), which design is founded in these constructs. This psychometric tool is useful in the assessment of cognitive control of stress, correlated with the function of dorsolateral prefrontal cortex. It has been validated for its use in the assessment of Portuguese people in situations of stress related to unemployment and economic insufficiency. Also, within the context of the cognitive control of stress, it is highlighted the usefulness of low resolution brain electromagnetic tomography (LORETA).

Electromagnetic tomography: consistency of images and groundwater prospecting

In crosswell observation of electromagnetic tomography, now there is no feasible way to calibrate the in situ radiation constant, while the effect of induced wave field always exists in observational data. Therefore the absorption coefficient obtained by a common used image reconstruction method is only a relative value. The consistency of tomograms in linked profiles inevitably is affected seriously. An improved equation involving the effect of induced wave field and an alternative tracing method to calculate the in situ radiation constant is proposed in the present paper. Based on the results from a series of parameter calibration performed in water and the experiments with rock samples, the standard meter readings of borehole electromagnetic systems, types EW—1 and JWQ—3, are accurately defined here. Additionally, frequency reduction and boundary smoothing of linked profiles are discussed. In research on groundwater prospecting in Tanggongta, Inner Mongolia, we used the above mentioned method and obtained the tomograms of linked profiles with good consistency. The absorption coefficient in the tomogram are not only reasonable and reliable, but also coincided with the result from rock parameter measurement. The depth, extension direction and water bearing structure of two aquifers were well detected. This result correctly guides hydrologic drilling there.

Calculation of 3D Sensitivity Matrix for Electromagnetic Tomography System Using Boundary Elements and the Perturbative Approach

Electromagnetic tomography(EMT) is a non-invasive imaging technique capable of mapping the conductivity and permeability of an object. In EMT, eddy currents are induced in the object by the activation coils,and the receiving coils can measure the EMT voltages. When the activation frequency is significantly large, we can treat the metallic targets as electrically perfect conductors(EPCs). In this situation, a thin skin approximation is reasonable and this type of scattering problem can be effectively treated by the boundary element method(BEM)formulated through integration equations. In this study, we compute three-dimensional(3D) sensitivity matrix between the sensors due to an EPC perturbation. Efficiency improvement is achieved through the utility of scalar magnetic potential. Two EPC objects, one sphere and one cube shaped, are simulated. The results agree well with the H dot H formula. Overall, we conclude that BEM can be used to calculate the 3D sensitivity matrix of an EMT system efficiently. This method is a general one for any shaped objects while the H dot H solution is only capable of producing the response for a small ball.

Archaeological investigation by geotomo-graphy: structure of the foundation of Yingxian timber pagoda

It is significant to take a non-destructive inspection, one of advanced techniques, for detecting the internal structure and the present status of ancient cultural relics. The results detected by geotomography in Yingxian timber pagoda, Shanxi Province, are presented in this paper. The embankment in the stepped foundation shows a three circular structure in horizontal: the circular platform core is hard, homogenous and unharmed, out of which there are some radial collapsed grooves. The middle circle with a thickness of 2 to 4 m is a compacted layer and its loading capacity decreases then. The outer protective layer has a larger porosity and a weak loading capacity. An abnormal body is found out in the core, which has a circular shape and a reverse high-absorption coefficient in the shallow part, but appears a long-band shape and a low-absorption coefficient in the deep part. It might be a disturbance caused by artificial activities: the shallow part is probably a channel filled with loosen soil and the deep part is a hidden cave. It is found that the foundation of the courtyard is homogenous and integrated. Two soft and weakened areas in the north are related to the long-term run-off and drainage of groundwater. The inclination of the timber pagoda to the northwest and northeast relates to several factors, such as the inherited subsidence of the northern foundation, the lower loading capacity of the outer stepped foundation, seismic activity and timber deformation.No.2 FENG R.et al.: ARCHAEOLOGICAL INVESTIGATION BY GEOTOMOGRAPHY

Assessment of the Neurological Activation in Law Enforcement under High Threat Situations: A Fuzzy Logic Approach

This paper discusses a law enforcement officer (LEO) study that involved expert and novice police deputies from a small-sized city located in the Southern U.S. A virtual reality range was utilized to simulate high threat scenarios that require split second decisions on the use of deadly force. A fuzzy-logic based controller was constructed to analyze electroencephalogram (EEG) data collected from the participants. The fuzzy controller made use of several functions associated with the different regions of the brain to correlate Brodmann areas to multiple outputs. Electromagnetic Tomography (i.e. LORETA) was used to identify where the signals from the surface electrodes originated within the brain through a process called source localization. Once the sources of the EEG signals were located, they were associated with corresponding Brodmann areas. The fuzzy controller then provided insights on the subjects’ exhibited neural activation behavior indicative of vision, memory, shape/distance, hearing/sound, and theory of mind. Comparing and contrasting experienced and novice officers allowed for a greater understanding of the neurological processes present in police deputies when dealing with high threat situations.