Effect of display size on utilization of traffic situation display for self-spacing task

The weather radar cathode ray tube (CRT) is the prime candidate for presenting cockpit display of traffic information (CDTI) in current, conventionally equipped transport aircraft. Problems may result from this, since the CRT size is not optimized for CDTI applications and the CRT is not in the pilot's primary visual scan area. The impact of display size on the ability of pilots to utilize the traffic information to maintain a specified spacing interval behind a lead aircraft during an approach task was studied. The five display sizes considered are representative of the display hardware configurations of airborne weather radar systems. From a pilot's subjective workload viewpoint, even the smallest display size was usable for performing the self spacing task. From a performane viewpoint, the mean spacing values, which are indicative of how well the pilots were able to perform the task, exhibit the same trends, irrespective of display size; however, the standard deviation of the spacing intervals decreased (performance improves) as the display size increased. Display size, therefore, does have a significant effect on pilot performance

Simulation study of traffic-sensor noise effects on utilization of traffic situation display for self-spacing task

The effect of traffic sensor noise on the ability of a pilot to perform an intrail spacing task was determined. The tests were conducted in a fixed base cockpit simulator configured as a current generation transport aircraft, with an electronic traffic display provided in the weather radarscope location. The true positions of the traffic were perturbed in both relative range and azimuth by random errors to simulate traffic sensor noise associated with an onboard sensor. The evaluation task involved simulated instrument approaches into a terminal area while maintaining self separation on a lead aircraft. Separation performance data and pilot subjective ratings and comments were obtained. The results of the separation data indicate that displayed traffic position errors, having standard deviation values up to 0.3-n.mi. range and 8 deg azimuth, had negligible effect on the spacing performance achieved by the pilots. Speed profiles of the lead aircraft, display of the lead aircraft groundspeed, and individual pilot techniques were found to significantly affect the mean spacing performance

Bracing Design for Torsional Bucking of Cold-Formed Steel Wall Stud Columns

A method is presented for calculating the required brace stiffness and strength to limit torsional buckling deformation in cold-formed steel wall stud columns. The bracing (bridging) design method utilizes recent insight from classical stability solutions that define twist of singly and doubly-symmetric columns with an initial twist imperfection as a function of column compressive load. A wall stud design example is provided

Bracing Design for Torsional Bucking of Cold-Formed Steel Wall Stud Columns

A method is presented for calculating the required brace stiffness and strength to limit torsional buckling deformation in cold-formed steel wall stud columns. The bracing (bridging) design method utilizes recent insight from classical stability solutions that define twist of singly and doubly-symmetric columns with an initial twist imperfection as a function of column compressive load. A wall stud design example is provided

The 1994 Elections: The Maine Vote in National Perspective

The 1994 elections at the national and state level resulted in significant changes all across the political landscape.University of Maine political scientist Matthew Moen analyzes the nature of that change and its implications for Maine

A parametric analysis of visual approaches for helicopters

A flight investigation was conducted to determine the characteristic shapes of the altitude, ground speed, and deceleration profiles of visual approaches for helicopters. Two hundred thirty-six visual approaches were flown from nine sets of initial conditions with four types of helicopters. Mathematical relationships were developed that describe the characteristic visual deceleration profiles. These mathematical relationships were expanded to develop equations which define the corresponding nominal ground speed, pitch attitude, pitch rate, and pitch acceleration profiles. Results are applicable to improved helicopter handling qualities in terminal area operations

On the diurnal variability in F2-region plasma density above the EISCAT Svalbard radar

Two long runs of EISCAT Svalbard Radar (ESR), in February 2001 and October 2002, have been analysed with respect to variability in the F2 region peak density and altitude. The diurnal variation in the F2 peak density exhibits one maximum around 12:00 MLT and another around 23:00 MLT, consistent with solar wind controlled transport of EUV ionized plasma across the polar cap from day to night. High density plasma patch material is drawn in through the cusp inflow region independent of IMF <I>B<sub>Y</sub></I>. There is no apparent IMF <I>B<sub>Y</sub></I> asymmetry on the intake of high density plasma, but the trajectory of its motion is strongly <I>B<sub>Y</sub></I> dependent. Comparison with the international reference ionosphere model (IRI2001) clearly demonstrates that the model does not take account of the cross-polar transport of F2-region plasma, and hence has limited applicability in polar cap regions

Term Limits, the Standing Committees, and Institutional Response

Through citizen initiative in 1993, Maine passed a term limits bill that now prevents legislators with eight years of consecutive service from seeking reelection. Although touted as a means of eliminating careerism in public service and as a means of bringing fresh blood and new policy initiative to Augusta, many now question whether limits on service have hampered legislative efficiency through the loss of experienced leadership and institutional memory. Moen and Palmer examine the impact of term limits on the legislature’s standing committees. While noting adverse impacts such as heavier workloads, they also find an institution hard at work to adapt, with leadership seeking new ways to improve operations and to orient new members to a rapidly changing environment