Investigations of Fracture Zones in Crystalline Rock by Borehole Radar

1985 ◽  
Vol 50 ◽  
Author(s):  
Olle Olsson ◽  
Lars Falk ◽  
Olof Forslund ◽  
Lars Lundmark ◽  
Eric Sandberg
Keyword(s):  
Crystalline Rock ◽  
Pulse Velocity ◽  
Radar System ◽  
Fracture Zones ◽  
Dipole Antennas ◽  
Short Pulses ◽  
Pulse Radar ◽  
Pulse Form ◽  
Position And Orientation ◽  
Very Short Pulses

AbstractA borehole pulse radar system has been developed as part of the International Stripa Project with the objective to identify and characterize fracture zones at a considerable distance from boreholes. The radar uses very short pulses, which are transmitted and received by dipole antennas inserted into the boreholes. The pulses are extremely broadband with center frequencies of 25–60 MHz corresponding to wavelengths of a few meters in the rock. At 25 MHz the attenuation in the Stripa granite is 28 dB/100 m and the pulse velocity is approximately 128 000 km/s. Reflection measurements have been used to identify fracture zones and determine their position and orientation. The zones often cause strong and well-defined reflections. Improvements in the pulse form and numerical filtering of the data have consequently made the radar a very efficient instrument for locating fracture zones. During measurements in Stripa reflections from fracture zones have been observed more than 100 m from the borehole.

Borehole radar applied to characterization of fracture zones

1989 ◽  
Vol 20 (2) ◽  
pp. 149 ◽  
Author(s):  
O. Olsson ◽  
L. Falk ◽  
O. Forslund ◽  
B. Niva ◽  
E. Sandberg
Keyword(s):  
Granitic Rock ◽  
Short Pulse ◽  
3D Models ◽  
Radar System ◽  
Fracture Zones ◽  
Borehole Logging ◽  
Single Hole ◽  
Pulse Radar ◽  
Borehole Radar

A new short-pulse radar system (RAMAC) developed by ABEM AB has now been in operation for three years during which more than 100 km of borehole logging has been performed. The bulk of the surveys have been in granites and gneisses.The RAMAC system operates at centre frequencies in the interval 20 to 60 MHz. At those frequencies single-hole reflection ranges of 50 to 150 m are normally obtained in gneissic and granitic rock. Cross-hole ranges have in some cases exceeded 300 m. The large probing range in combination with resolution of the order of a few metres makes borehole radar a unique technique for investigation of fracture zones in crystalline rock.Case histories illustrate application of the RAMAC system in three different configurations (single-hole reflection, cross-hole reflection, and cross-hole tomography) and demonstrate how combination of these three can yield consistent 3D models of fracture zones and other structures.

Transient response of resistively loaded dipole antennas for pulse radar

1993 ◽  
Vol 76 (7) ◽  
pp. 54-62
Author(s):  
Masanobu Kominami ◽  
Tohru Takagi ◽  
Shinnosuke Sawa ◽  
Takashi Kikuta
Keyword(s):  
Transient Response ◽  
Dipole Antennas ◽  
Pulse Radar

Electrical borehole measurements for the mapping of fracture zones in crystalline rock

1984 ◽  
Vol 22 (3-4) ◽  
pp. 203-216 ◽  
Author(s):  
Ante Jämtlid ◽  
Kurt-åke Magnusson ◽  
Olle Olsson ◽  
Leif Stenberg
Keyword(s):  
Crystalline Rock ◽  
Fracture Zones

scholarly journals LOCALIZATION OF MACROMOLECULES IN ESCHERICHIA COLI

1961 ◽  
Vol 9 (3) ◽  
pp. 539-553 ◽  
Author(s):  
Lucien G. Caro
Keyword(s):  
Escherichia Coli ◽  
Poisson Distribution ◽  
Cross Sections ◽  
Morphological Changes ◽  
Nuclear Region ◽  
High Concentration ◽  
Short Pulses ◽  
Thin Sections ◽  
Change Concerns ◽  
Very Short Pulses

If thin sections of Escherichia coli, labeled uniformly with tritium, are radioautographed calculations, based on the distribution of section sizes show that the number of H3 decays per section should be very close to a Poisson distribution. We might, therefore, expect that the distribution of radioautographic grain counts among random cross-sections should follow a Poisson distribution. It can then be inferred that a deviation from a Poisson indicates a high concentration of label in a preferred region. This region can then be identified by analysis of serial section and comparison with electron micrographs. Sections of cells labeled with leucine-H3 gave a Poisson distribution of grain counts, and it was concluded that proteins were distributed fairly uniformly throughout the cell. The situation was not changed if labeled cells were placed in chloramphenicol or if very short pulses of label were used. When Escherichia coli is grown in presence of chloramphenicol a major morphological change concerns the nuclear region: it becomes more regular in outline, nearly spherical, and occupies a smaller proportion of the cell length. The previously described association between DNA labeled with thymidine-H3 and the nuclear region was confirmed by showing that the distribution of the label in the cell followed exactly the morphological changes of the nuclear region. It was also shown that the concentration of DNA in the nuclear region was at least 45 times higher than that of the cytoplasm. Several morphological features of cells grown in chloramphenicol and examined in the electron microscope are discussed.

The response of 741 op amps to very short pulses

1980 ◽  
Vol 15 (5) ◽  
pp. 908-910 ◽  
Author(s):  
V.G. Ruediger ◽  
B.J. Hosticka
Keyword(s):  
Short Pulses ◽  
Op Amps ◽  
Very Short Pulses
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