Summary report of the Simulation Committee

Topics discussed by the simulation committee included: (1) simulators and their uses; (2) atmospheric disturbance modeling requirements; (3) Status of simulators' capabilities for modeling disturbances; and (4) status of atmospheric disturbance models. Also discussed were specific problem areas; simulation studies criteria, aircraft/atmospheric disturbance response modeling and pilot learning effects

Characteristics of wake vortex generated by a Boeing 727 jet transport during two-segment and normal ILS approach flight paths

A series of flight tests was conducted to evaluate the vortex wake characteristics of a Boeing 727 (B727-200) aircraft during conventional and two-segment ILS approaches. Twelve flights of the B727, which was equipped with smoke generators for vortex marking, were flown and its vortex wake was intentionally encountered by a Lear Jet model 23 (LR-23) and a Piper Twin Comanche (PA-30). Location of the B727 vortex during landing approach was measured using a system of photo-theodolites. The tests showed that at a given separation distance there were no readily apparent differences in the upsets resulting from deliberate vortex encounters during the two types of approaches. Timed mappings of the position of the landing configuration vortices showed that they tended to descend approximately 91 m(300 ft) below the flight path of the B727. The flaps of the B727 have a dominant effect on the character of the trailed wake vortex. The clean wing produces a strong, concentrated vortex but as the flaps are lowered, the vortex system becomes more diffuse. Pilot opinion and roll acceleration data indicate that 4.5 n.mi. would be a minimum separation distance at which roll control of light aircraft (less than 5,670 kg (12,500 lb) could be maintained during parallel encounters of the B727's landing configuration wake. This minimum separation distance is generally in scale with results determined from previous tests of other aircraft using the small roll control criteria

Flight tests of a clear-air turbulence alerting system

The detection of clear-air turbulence (CAT) ahead of an aircraft in real-time by an infrared (IR) radiometer is discussed. It is noted that the alter time and reliability depend on the band-pass of the IR filter used and on the altitude of the aircraft. Results of flights tests indicate that a bandpass of 20 to 40 microns appears optimal for altering the aircraft crew to CAT at times before encounter of 2 to 9 min. Alert time increases with altitude, as the atmospheric absorption determining the horizontal weighting is reduced

Flight test investigation of the vortex wake characteristics behind a Boeing 727 during two-segment and normal ILS approaches (A joint NASA/FAA report)

Flight tests were performed to evaluate the vortex wake characteristics of a Boeing 727 aircraft during conventional and two-segment instrument landing approaches. Smoke generators were used for vortex marking. The vortex was intentionally intercepted by a Lear Jet and a Piper Comanche aircraft. The vortex location during landing approach was measured using a system of phototheodolites. The tests showed that at a given separation distance there are no readily apparent differences in the upsets resulting from deliberate vortex encounters during the two types of approaches. The effect of the aircraft configuration on the extent and severity of the vortices is discussed

Experimental evaluation of the usage of ad hoc networks as stubs for multiservice networks

This paper describes an experimental evaluation of a multiservice ad hoc network, aimed to be interconnected with an infrastructure, operator-managed network. This network supports the efficient delivery of services, unicast and multicast, legacy and multimedia, to users connected in the ad hoc network. It contains the following functionalities: routing and delivery of unicast and multicast services; distributed QoS mechanisms to support service differentiation and resource control responsive to node mobility; security, charging, and rewarding mechanisms to ensure the correct behaviour of the users in the ad hoc network. This paper experimentally evaluates the performance of multiple mechanisms, and the influence and performance penalty introduced in the network, with the incremental inclusion of new functionalities. The performance results obtained in the different real scenarios may question the real usage of ad-hoc networks for more than a minimal number of hops with such a large number of functionalities deployed

Characterization of Vernal Pools Across National Parks in the Great Lakes Region

Vernal pools are small, ephemeral wetlands that become inundated each spring and provide many ecosystem services, including providing critical habitat to amphibians and invertebrates as their temporary nature keeps them free of fish. We collected data on vernal pool characteristics throughout five Great Lakes National Parks: Pictured Rocks National Lakeshore, Sleeping Bear Dunes National Lakeshore, Apostle Islands National Lakeshore, Isle Royale National Park, and Voyagers National Parks. Our goals were to characterize and assess how vernal pools vary within and across the five national parks, and determine which characteristics are most correlated with the presence of vernal pool indicator species. We sampled 139 pools during spring of 2021 and 2022 where we collected data on pool characteristics related to hydrology, soils, vegetation, geomorphology, and indicator species. We found that vernal pool substrate and forest type does vary between the different parks. Many vernal pool qualities are driven by the type of substrate they occur on and overstory canopy species and amount of tree cover. We also created a classification system that most highly correlated to indicator species presence and can be used in remote sensing products, resulting in a three-class system based on overstory species composition: Deciduous, Coniferous, and Open. Indicator species were more likely to occur in pools with either a deciduous or open canopy than pools with a coniferous canopy. This information can be used to inform land managers within the Great Lakes of vernal pool characteristics they can expect, and which pools are hotspots for indicator species

A METHODOLOGY FOR UNIT TESTING ACTORS IN PROPRIETARY DISCRETE EVENT BASED SIMULATIONS

This paper presents a dependency injection based, unit testing methodology for unit testing components, or actors, involved in discrete event based computer network simulation via an xUnit testing framework. The fundamental purpose of discrete event based computer network simulation is verification of networking protocols used in physical–not simulated–networks. Thus, use of rigorous unit testing and test driven development methodologies mitigates risk of modeling the wrong system. We validate the methodology through the design and implementation of OPNET-Unit, an xUnit style unit testing application for an actor oriented discrete event based network simulation environment, OPNET Modeler