Experimental Studies to Investigate Pressure Loading on Target Plates

The pressure distribution on the bottom of an armored vehicle caused by a detonating explosive buried in soil has been long of interest in the community of the Armed Services. This experimental study discusses results from small-scale tests conducted to determine the distribution of pressure on target plates when subjected to loading due to the detonation of buried mines. A new methodology has been developed in order to measure the pressure - time profiles on the bottom of a vehicle. The tests are conducted by using water, saturated sand, and dry sand as the loading media. Different stand off distances are investigated using saturated sand. Kolsky bars and pressure sensors, on the target plate, are used to determine the free-field pressure - time profile of the output of the charge at any location for the vehicle bottom. For verification of the pressure results at certain distances, the specific impulse measured by utilizing different size round plates are employed. In order to investigate the loading mechanisms, high speed cameras are applied. The small-scale test results can be scaled to full scale by using verified scaling laws. The results of this research are of interest to the U.S NAVY and U.S ARMY in order to develop and evaluate computer codes which are mainly used in soil models. These computer codes are to be used to design mine resistant personnel carriers and in the field to predict the threat assessments

An effective method to read out large scintillator areas with precise timing

Using scintillator tile technology several square meters of plastic scintillator are read out by only two photomultiplier with a time precision of about 1.5 nsec. Two examples are discussed to build a detector based on this technology to search for cosmic muons and neutrinos.Comment: 8 pages, 9 figures. Contributed to Workshop on Scintillating Fiber Detectors (SCIFI97), Notre Dame, IN, 2-6 Nov 199

HRXRD study of the effect of a nanoporous silicon layer on the epitaxial growth quality of GaN layer on the templates of SiC/por-Si/c-Si

Using High Resolution X-ray Diffraction (HRXRD) diagnostic techniques the influence of the transition layer of nanoporous silicon on the practical implementation and certain features of the epitaxial growth of GaN layers with the use of molecular beam epitaxy were investigated by means of plasma activation of nitrogen (MBE PA) on the templates of SiC/por-Si/c-Si. For the first time it was shown that introducing of the transition layer of nanoporous silicon in the template of SiC/por-Si/c-Si where the layer of 3C-SiC was obtained by substitution of the atoms had a number of indisputable advantages as compared with conventional silicon substrates. Particularly, such an approach, in fact, enabled a 90% reduction in the level of stresses in the crystalline lattice of the epitaxial GaN layer which was synthesized on SiC surface of SiC/por-Si/c-Si template by means of MBE PA technique as well as to decrease some of vertical dislocations within GaN layer

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