76,859 research outputs found
The use of ERTS-1 images in the search for large sulfide deposits in the Chagai District, Pakistan
The author has identified the following significant results. Visual examination of color composites was tested under relatively ideal conditions for direct detection of large hydrothermal sulfide deposits at the low-grade porphyry copper deposit at Saindak, western Chagai District, Pakistan. The Saindak deposit is characterized by an elongate zone of easily eroded sulfide-rich rock surrounded by a resistant rim of hornfels and propylitically altered rock. The geomorphic features related to the Saindak deposit are easily distinguished on ERTS-1 images. Attempts to detect a color anomaly using false-color composites were not successful. About 36,000 square km of the western Chagai District were examined on false-color composites for direct evidence of large sulfide deposits. New geologic information acquired from the images was used in conjunction with the known geology to evaluate two previously known proposed areas and to suggest seven additional targets for field checking, one of which is proposed on the basis of tonal anomaly alone. The study also showed that Saindak-type deposits are not likely to be present in some extensive areas of the Chagai District; and also that a rim like that at Saindak does not form if regional metamorphism has increased the resistance of the country rock to erosion
Use of ERTS-1 images in the search for porphyry copper deposits in Pakistani Baluchistan
Geomorphic features related to a known porphyry copper deposit at Saindak, western Chagai District, Pakistan, are easily distinguished on ERTS-1 images. New geologic information from the images was used in conjunction with known geology to evaluate one previously known prospect area and to suggest two additional ones, but no new prospects were recognized on the basis of the images alone. The study also showed that Saindak-type deposits are not likely to be present in some extensive areas of the Chagai District. The Saindak deposit is in an area of relatively easily eroded folded sedimentary and volcanic rocks. The deposit is characterized by an elongate zone of easily eroded sulfide-rich rock surrounded by this rim and the central sulfide-rich valley are conspicuous features on the images. Swarms of dikes are probably useful for distinguishing real rims from other resistant rock types, but there is no expression of them on the image, although they are easily seen on aerial photographs of the Saindak rim
Analysis study of multispectral data, ERTS-A, from an area in West Pakistan
There are no author-identified significant results in this report
Bosonic Preheating in Left-Right-Symmetric SUSY GUTs
We investigate the possibility of a bosonic preheating in the simplest model
of supersymmetric Hybridinflation (F-term inflation), which was considered
first by Dvali et al. Here the inflationary superpotential is of the
O'Raifertaigh-Witten type. The end of inflation is related to a non-thermal
phase transition, which in the context of left-right symmetric models lowers
the rank of the gauge group. Using the homogeneous classical field ansatz for
the appearing condensates, our results indicate that the parametric creation of
bosonic particles does not occure in the model under consideration.Comment: 14 pages, 6 figure
Quality control of microelectronic wire bonds
Report evaluates ultrasonic bonding of small-diameter aluminum wire joined to ceramic substrates metalized with thin-film and thick-film gold. Quick testing technique for nondestructive location of poor wire bonds is also presented
Complementary code and digital filtering for detection of weak VHF radar signals from the mesoscale
The SOUSY-VHF-Radar operates at a frequency of 53.5 MHz in a valley in the Harz mountains, Germany, 90 km from Hanover. The radar controller, which is programmed by a 16-bit computer holds 1024 program steps in core and controls, via 8 channels, the whole radar system: in particular the master oscillator, the transmitter, the transmit-receive-switch, the receiver, the analog to digital converter, and the hardware adder. The high-sensitivity receiver has a dynamic range of 70 dB and a video bandwidth of 1 MHz. Phase coding schemes are applied, in particular for investigations at mesospheric heights, in order to carry out measurements with the maximum duty cycle and the maximum height resolution. The computer takes the data from the adder to store it in magnetic tape or disc. The radar controller is programmed by the computer using simple FORTRAN IV statements. After the program has been loaded and the computer has started the radar controller, it runs automatically, stopping at the program end. In case of errors or failures occurring during the radar operation, the radar controller is shut off caused either by a safety circuit or by a power failure circuit or by a parity check system
The mobile Sousy-Doppler radar: Technical design and first results
A mobile VHF Doppler system was developed. The electronic part is installed in a 20 ft container and tested using a special log periodic aerial to illuminate the 300 m dish. The system was extended by designing a mobile phased antenna array with finally 576 Yagi elements. The grouping of the single Yagis, the system of transmission lines, the phase shifters, the power splitters and the T/R switch are described. Results from the first two campaigns and a survey of future programs demonstrating the flexibility of this mobile system are summarized
The azimuthal asymmetry of unpolarized dilepton production at the -pole
We calculate the Boer-Mulders effect contribution to the
azimuthal asymmetry of unpolarized dilepton production near the -pole. Based
on the tree-level expression in the transverse momentum dependent factorization
framework, we show that the corresponding asymmetry near the -pole is
negative, which is opposite to the asymmetry in the low region, dominated
by the production via a virtual photon. We calculate the asymmetry generated by
the Boer-Mulders effect near the -pole at RHIC, with GeV. We
find that the magnitude of the asymmetry is several percent, and therefore it
is measurable. The experimental confirmation of this sign change of the
asymmetry from the low region to the -pole provides direct evidence of
the chiral odd structure of quarks inside an unpolarized nucleon.Comment: comments and references added, journal versio
How to bypass Birkhoff through extra dimensions (a simple framework for investigating the gravitational collapse in vacuum)
It is fair to say that our current mathematical understanding of the dynamics
of gravitational collapse to a black hole is limited to the spherically
symmetric situation and, in fact, even in this case much remains to be learned.
The reason is that Einstein's equations become tractable only if they are
reduced to a 1+1 dimensional system of partial differential equations. Due to
this technical obstacle, very little is known about the collapse of pure
gravitational waves because by Birkhoff's theorem there is no spherical
collapse in vacuum. In this essay we describe a new cohomogeneity-two symmetry
reduction of the vacuum Einstein equations in five and higher odd dimensions
which evades Birkhoff's theorem and admits time dependent asymptotically flat
solutions. We argue that this model provides an attractive 1+1 dimensional
geometric setting for investigating the dynamics of gravitational collapse in
vacuum.Comment: 7 pages, received "honorable mention" in 2006 Gravity Research
Foundation essay contes
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