Hall D.C.,MacAulay Brown Inc.
Many of the objections to implementing Risk Management and acting upon risk results hinge on the subjectivity of the risk assessment system. This subjectivity makes it difficult to make risk assessments justifiable, repeatable, and comparable over an entire project, program, or organization. One cannot easily justify assigning a 30% likelihood to a risk occurring when others with more, the same, or less experience are ascribing a 60% likelihood of occurrence to a similar risk. How to get all (or most) risk assessments, regardless of type (software, hardware, integration, programmatic, external, etc.), justifiable, repeatable, and comparable has been one of the holy grails of Risk Management for years. The methodology outlined in this paper meets at least some of this requirement. The methodology requires incorporating the Likelihood of Occurrence into a set of specifically defined sublevels under each risk category rather than using it as a separate multiplication factor. Basically, the assumption behind this methodology is that the more mature the process, the more experience available, the more detailed the design, etc., the lower the likelihood of occurrence of a specific risk becomes. Making this assumption, incorporating the likelihood into each specific sublevel and requiring justification for each choice then allows the establishment of more representative scores for project risks and allows risk information to be presented in a justifiable, repeatable, and comparable fashion. Copyright © 2010 Wiley Periodicals, Inc. Source
He H.,University of Nebraska - Lincoln |
Yang J.,University of Nebraska - Lincoln |
Kosinski J.A.,MacAulay Brown Inc.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
We perform a theoretical analysis of the secondorder in-plane acceleration sensitivity of a Y-cut quartz thickness-shear mode resonator. The second-order nonlinear theory of elasticity for anisotropic crystals is used to determine the biasing fields in the resonator under in-plane acceleration. The acceleration-induced frequency shift is determined from a perturbation analysis based on the plate equations for small-amplitude vibrations superposed on a finite bias. We show that, whereas the first-order acceleration-induced frequency shift is zero for a structurally symmetric resonator under in-plane acceleration, the second-order frequency shift is nonzero and is quadratic in the acceleration. As the fourth-order nonlinear elastic constants of quartz have never been measured, we can only estimate the magnitude of the second-order frequency shift. For a particular case of interest, we find Δω/ω0~10-18, 10-16, and 10-14 when the acceleration is 1, 10, and 100 g, respectively. © 1986-2012 IEEE. Source
Horvath M.S.,MacAulay Brown Inc. |
Gorham L.A.,Air Force Research Lab |
Rigling B.D.,Wright State University
IEEE Transactions on Aerospace and Electronic Systems
The polar format algorithm (PFA) for synthetic aperture radar (SAR) image formation utilizes a first-order Taylor approximation of the differential range to improve computational efficiency, leading to image distortion and defocus. Limiting scene size by bounding the second-order Taylor series terms can restrict the impact of these errors, or alternatively, one may correct for these errors through spatially-variant filtering in post processing. In this letter we analyze the increase in allowable scene size that is realized through such processing. © 1965-2011 IEEE. Source
Rigling B.D.,Wright State University |
Roush C.,MacAulay Brown Inc.
IEEE National Radar Conference - Proceedings
Classification of radar waveform phase modulation based on a sequence of observations is a simple problem complicated by a number of nuisance parameters. Without prior knowledge of waveform carrier frequency, time offset, amplitude, initial phase, and bandwidth, application of a matched filter classifier is not achievable. One must instead rely on waveform features that are invariant to these parameters. This paper presents an invariant feature set for waveform classification. Testing of these features on simulated radar waveforms has illustrated the desired invariance properties and robustness to low signal-to-noise ratio. © 2010 IEEE. Source
MacAulay Brown Inc. | Date: 2014-11-21
A method and apparatus for low voltage conversion and energy storage uses a charge pump array including a first set of capacitors in parallel with a second set of capacitors and switches for selectively coupling the first and second set of capacitors to a variable input DC voltage. A data processor programmably controls one or more of the switches to couple the first and second set of capacitors to the variable input DC voltage for a variable first time period during which the input DC voltage charges the first and second set of capacitors to a DC voltage level. An energy storage device is switchably coupled to an output of the charge pump array. The data processor programmably controls one or more of the switches to couple the charge pump array output to the energy storage device for a variable second time period during which a voltage stored across each of the capacitors during the first time period is combined to produce a higher voltage significantly higher than the input DC voltage, the higher voltage being provided to the energy storage device.