Showing papers by "ARPA-E published in 1993"

Cluster analysis of seismic moment tensor orientations

Abstract: SUMMARY This paper demonstrates that well-known methods of cluster analysis and multivariate data analysis are useful for geodynamic interpretation of seismic moment tensors. To use these methods, moment tensors are expressed as vectors in a 6-D space. These are vectors in a rigorous sense, rather than an arbitrary set of ordered numbers, because a dot product can be defined that is independent of the coordinate system. In this vector space, non-isotropic moment tensors are a 5-D linear subspace and normalized moment tensors are unit vectors, or points on a unit sphere. Distance along a great circle of the unit sphere satisfies reasonable requirements for any measure of the difference between normalized moment tensors. In regions with a few isolated sets of orientations, cluster analysis based on the great circle distance identifies the same groups of earthquakes that a seismologist would. Figures based on principal component analysis and discriminant analysis illustrate orientation clustering better than equal area projections of moment tensor principal axes. In one case where clusters have been claimed to exist, orientations appear to be continuously distributed and no evidence is found for separate populations of moment tensors.

Perspective on underground and obscured-target detection and imaging

Abstract: This briefing focusses on some of the work forming the background of today's state of the ground probing radar art, and will attempt to draw conclusions about the prospects of this technology. We will cover some of the results achieved to date by many of the laboratories and organizations engaged in this work, including some work that is up to 20 years old, as well as work accomplished in the last few weeks. The spectrum of results is quite varied, ranging from the disappointing to the encouraging. We will attempt to identify some of the factors leading to or limiting success in this area and define some likely prospects for further applications. Finally, we will describe some of the research efforts that will be required to fully evaluate the feasibility of these hoped-for applications.

A road map to ARPA involvement in electronic packaging

Abstract: The application of advanced electronic packaging and interconnect (EP/I) technology by US Department of Defense's Advance Research Projects Agency are discussed. The EP/I domain includes packages, multichip modules (MCMs), connectors, printed circuit boards (PCBs), boxes, backplanes, and cages. The EP/I physical technologies, including diamond substrates, superconductors, and metal matrix packages, are discussed, and information technologies are described. >

High-performance, miniaturized processor trends

Abstract: It is widely recognized that processors developed for many different uses in the near future must be faster, more versatile, easier to use, less costly, and -- in many cases -- smaller than those currently available. The required increase in functionality is associated with many factors, including: (1) the increasing complexity of the algorithms being developed for various applications (e.g., aided/automatic target recognition -- ATR); (2) the development of larger sensor arrays for both focal plane arrays (FPAs) and synthetic aperture radars (SARs); (3) real-time performance needs for processing-intensive systems deployed on a wide variety of platforms; (4) more-stringent requirements on sensor resolution; (5) the need for effective sensor fusion to handle data available from multiple sources; (6) increased intra- and inter- platform communications; and (7) hardware/software development and implementation costs. This paper discusses ongoing and required work related to component development and electronics packaging critical to meeting future processing requirements within reasonable size, weight, and power constraints.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.