Mitre Corporation

About: Mitre Corporation is a company organization based out in Bedford, Massachusetts, United States. It is known for research contribution in the topics: Air traffic control & National Airspace System. The organization has 4884 authors who have published 6053 publications receiving 124808 citations. The organization is also known as: Mitre & MITRE.

Tuning schema matching software using synthetic scenarios

Abstract: Most recent schema matching systems assemble multiple components, each employing a particular matching technique. The domain user must then tune the system: select the right component to be executed and correctly adjust their numerous "knobs" (e.g., thresholds, formula coefficients). Tuning is skill- and time-intensive, but (as we show) without it the matching accuracy is significantly inferior.We describe eTuner, an approach to automatically tune schema matching systems. Given a schema S, we match S against synthetic schemas, for which the ground truth mapping is known, and find a tuning that demonstrably improves the performance of matching S against real schemas. To efficiently search the huge space of tuning configurations, eTuner works sequentially, starting with tuning the lowest level components. To increase the applicability of eTuner, we develop methods to tune a broad range of matching components. While the tuning process is completely automatic, eTuner can also exploit user assistance (whenever available) to further improve the tuning quality. We employed eTuner to tune four recently developed matching systems on several real-world domains. eTuner produced tuned matching systems that achieve higher accuracy than using the systems with currently possible tuning methods, at virtually no cost to the domain user.

Source enumeration in a correlated signal environment

Abstract: The authors present a simple method for determining the number of signals impinging on a uniform linear array that is applicable even in the extreme case of fully correlated signals. This technique uses what they term modified rank sequences, which is a modification of the construction implicit in the matrix decomposition method of Di (1981). They prove that if a particular rank sequence stabilizes (the last two terms of the sequence are equal) to a value strictly less then the common row size of the defining block matrices, then this value equals the number of signals, provided that the number of signals has not exceeded a Bresler-Macovski (1986) type bound. Using the above characterization of stability, they formulate an algorithm that either determines the number of signals or indicates that the resolution capability of the algorithm has been exceeded. They also provide theorems that show that under certain conditions, a rank sequence can stabilize to a value strictly less than the number of signals. This result allows them to find simple counterexamples to all of the existing rank sequence methods. >

Digital, matrix and intermediate-frequency scanning

Abstract: This paper describes circuit configurations for phased arrays which to some degree circumvent the difficulty of obtaining simple electronically-controlled phase shifters for UHF and Microwave frequencies. These configurations include phase shifters operating at an intermediate (i-f) frequency, frequency-scanning systems, within-pulse scanning, switched-multiple-beam antennas, switched-delay-line phase shifters, and digital-processing delay techniques.

Structured assurance cases: three common standards

Abstract: For safety-, mission-, or security-critical systems, there are typically regulations or acquisition guidelines requiring a documented body of evidence to provide a compelling justification that the system satisfies specified critical properties. Current frameworks suggest the detailed outline of the final product but leave the truly meaningful and challenging aspects of arguing assurance to the developers and reviewers. We began with two major hypotheses. We selected a software notation suitable for building structured safety cases and applied it to three disparate assurance standards. Each of the three standard mapping efforts is discussed, along with the problems we encountered. In addition to the standards, we used the notation to structure an assurance case for a practical security-critical system, and we describe the lessons learned from that experience. We conclude with practical options for using our mappings of the standards and how well our initial hypotheses are borne out by the project.

Dynamic Stresses and Displacements Around Cylindrical Discontinuities Due to Plane Harmonic Shear Waves

Abstract: : The problem of dynamic stresses and displacements around a cavity and rigid inclusion of arbitrary density is examined for an elastic medium during the passage of a plane shear wave. In the cavity case, the dynamic stresses and displacements are found to be dependent upon the incident wave number and Poisson's ratio of the medium. In the rigid inclusion case, it is found that dynamic stresses and the rigid body rotation and translation are dependent upon the incident wave numbers, the Poisson's ratio, and the density ratio of the medium and the insert. Close coupling is observed between the stresses and the rigid body motion of the insert.