Comparison of closed loop model with flight test results

An analytic technique capable of predicting the landing characteristics of proposed aircraft configurations in the early stages of design was developed. In this analysis, a linear pilot-aircraft closed loop model was evaluated using experimental data generated with the NT-33 variable stability in-flight simulator. The pilot dynamics are modeled as inner and outer servo loop closures around aircraft pitch attitude, and altitude rate-of-change respectively. The landing flare maneuver is of particular interest as recent experience with military and other highly augmented vehicles shows this task to be relatively demanding, and potentially a critical design point. A unique feature of the pilot model is the incorporation of an internal model of the pilot's desired flight path for the flare maneuver

Turbomachinery rotor support with damping

Damping seals, damping bearings, and a support sleeve are presented for the ball bearings of a high speed rotor. The ball bearings consist of a duplex set having the outer races packaged tightly within the sleeve while the sleeve provides a gap with a support member so that the bearings may float with the sleeve. The sleeve has a web extending radially between the pair of outer races and acts in conjunction with one or more springs to apply an axial preload to the outer races. The sleeves have a series of slits which provide the sleeve with a spring-like quality so that the spring acts to center the rotor upon which the bearings are mounted during start up and shut down. A damping seal or a damping bearing may be used in conjunction with the ball bearings and supporting sleeve, the damping seal and damping bearing having rotor portions including rigid outer surfaces mounted within the bore of a stator portion having triangular shaped pockets on the surface facing the rotor. Axial gates are provided between adjacent pockets in sections of the stator permitting fluid to flow with less resistance axially relative to the flow of fluids circumferentially between the rotor and the stator

Video-Based Information Systems in Academic Library Media Centers

published or submitted for publicatio

GASB Statement No. 31: Why No Controversy?

Fair value reporting of investments in the financial statements of commercial enterprises is required under FASB Statement No. 115. The standard created much controversy when issued due to provisions that changes in fair values of certain investments were recognized in the operating statement. A major concern to many organizations was the volatility these recognized, but unrealized, changes in fair value would create in reported earnings. When the GASB issued Statement No. 31 requiring fair value reporting of investments there was little controversy concerning volatility to reported earnings of governmental entities, even though the standard required much broader application of fair value reporting. This study examined a possible explanation for the lack of controversy surrounding fair value reporting in the public sector. An analysis of the financial reports of the major U.S. municipalities provided empirical evidence of the significance of investments earnings to municipal revenues, investment assets to total assets, and the significance of changes in fair values of investments to investment earnings and total revenues. Financial reports and accompanying notes for fiscal years 1994 to 1998 were examined. Results indicate that overall, investments earnings were not a significant component of governmental fund revenues. However, investment earnings were significant for certain governmental fund types. The difference between costs and fair market values of investments also did not appear to be material to most governmental funds. The minimal impact of the fair value reporting on earnings offers a partial explanation for the lack of debate surrounding adoption of fair value reporting of investment by governmental entities