Its vertical resolution,depth of investigation and environmental effects including shoulder,invasion.

1m and depth of investigation is equivalent to Deep LL3.

,the key parts characteristics of array EWR logging while drilling apparatus were introduced,the selec- tion principle for emission frequency,space length,spacing and other important parameters,and the relations between emission frequency,space length,spacing,coil number, collar structure and apparatus depth of investigation were expounded.

A theoretical study on detecting depth and spacing of density logging;

It is known that the detecting depth of optical coherence tomography ( OCT) can be enhanced by hyper-osmotic agent.

The author queries in this paper the theory that the TEMS exploration depth depends on the strength of the loop s magnetic moment(M=IL2),and that under the circumstance of limited field source power,the depth will be effectively controlled by loop area.

Four basic problems in the application of Ground penetrtion radar are discussed in this paper:(1) the wave impedance of electromagnetic wave transmission in strata; (2) the reflectivity and transmissivity of electromagnetic field at the subsurface of strata; (3) reflective phase and propagating velocity of electromagnetic wave in strta; (4) detection depth of the Ground penetration radar.

According to the electric features of North China type coal field,the principle analysis and exploration cases of the electric magnetic probing showed that a largest pole distance,longer observation time and lower frequency would be needed to reach the expected probing depth.

To investigate the effect of different probing depths during cardiac optical mapping,the electrical transmural propagation model,and the fluorescence transport model were adopted to simulate the distribution of transmembrane potentials during the transmural propagation and the fluorescence signals coming form three different optical probing depths.

The maximum probing depth is 2000m when the method is used reasonab.