The need for mass prediction methods and the problems associated with them are discussed. Two methods for wing mass prediction are then presented, one based on an analysis of empirical data and the other having a theoretical basis. The two methods have been tested against a substantial number of actual wing masses covering all types of aircraft. Overall the results are acceptable although there are some, specijic, discrepancies. While the empirical method is easier to use and actually shows less scatter, the theoretically based method does enable particular features of the wing design to be allowed for and gives somewhat better correlation with actual wing masses.
Seismic surveys are often constrained by the time needed to activate all the required sources so the source signals do not interfere with each other. Simultaneous source seismic acquisition, also referred to as blended acquisition, is an effective method for reducing the cost and improving the quality of seismic surveys by eliminating the requirement that the sources do not interfere with each other. Independent simultaneous shooting is a unique form of blended acquisition in which sources operate independently of each other and the receiver recording is continuous. This acquisition method is particularly efficient and robust in obtaining high-density source grids for land and marine surveys. Processing the simultaneous source data depends on the randomness of the shot times to create a situation where the signal is coherent, and the interference is random in common-receiver gathers. Although the older and simpler method of separating interfering shots with random noise attenuation works well when the residual interference noise left by the random noise attenuation is acceptable, higher separation quality is possible using a shot separation process based on sparse inversion and compressive sensing methodology. We found that the resulting simultaneous source surveys produced images that were equivalent to or better than conventional seismic surveys, while requiring less acquisition effort, thus reducing costs.
This paper reviews information that may be used by a potential enemy to detect and track an aircraft. In particular it is concerned with a passive approach by the enemy, namely the interception of acoustic, infrared, visual, and miscellaneous self-emissions. The origins of these emissions are described and means of eliminating them or reducing their intensity are discussed. Emphasis is placed on the impact of these so-called stealth techniques on the design of the aircraft as a whole.
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