CREAM: 70 days of flight from 2 launches in Antarctica

The Cosmic-Ray Energetics And Mass balloon-borne experiment has been launched twice in Antarctica, first in December 2004 and again in December 2005. It circumnavigated the South Pole three times during the first flight, which set a flight duration record of 42 days. A cumulative duration of 70 days within 13 months was achieved when the second flight completed 28 days during two circumnavigations of the Pole on 13 January 2006. Both the science instrument and support systems functioned extremely well, and a total 117 GB of data including 67 million science events were collected during these two flights. Preliminary analysis indicates that the data extend well above 100 TeV and follow reasonable power laws. The payload recovered from the first flight has been refurbished for the third flight in 2007, whereas the payload from the second flight is being refurbished to be ready for the fourth flight in 2008. Each flight will extend the reach of precise cosmic-ray composition measurements to energies not previously possible.     

Study of Dynamic Loads of Aircraft Bevel Gear Systems

This paper studies the dynamic loads of bevel gears with circular and straight teeth with the overlap factors less than two (ε_α < 2) and more than two (ε_α > 2). The advantages of the gears with straight teeth with ε_α > 2 are shown.     

Fate of prebiotic adenine

Equilibrium adsorption isotherm data for the purine base adenine has been obtained on several prebiotically relevant minerals by frontal analysis using water as a mobile phase. Adenine is far displaced toward adsorption on pyrite (FeS2), quartz (SiO2), and pyrrhotite (FeS), but somewhat less for magnetite (Fe3O4) and forsterite (Mg2SiO4). The prebiotic prevalence of these minerals would have allowed them to act as a sink for adenine; removal from the aqueous phase would confer protection from hydrolysis as well, establishing a nonequilibrium thermodynamic framework for increased adenine synthesis. Our results provide evidence that adsorption phenomena may have been critical for the primordial genetic architecture.     

Decentralized reduced-order filters

Continuous and discrete methods of designing simple reduced-order local filters within a large-scale network are suggested. The filters are designed to estimate only the local variables of interest and not the entire state vector. The method has the advantage that one need not know the mathematical models of the subsystems generating the interconnection variables. The order of the filter can be small enough so that there is no computational burden associated with the filter. The disadvantage of the method is that performance is lost by using a reduced-order filter instead of a full-order filter. An example that demonstrates one application in the aerospace industry is presented     

A Modification to Improve the Inverse Filter of Senmoto and Childers

An inverse filter, contained in a recently published paper by Senmoto and Childers, is improved by the application of a shaping function derived by Turin in an earlier paper.     

A Practical Distribution-Free Detection Procedure for Multiple-Range-Bin Radars

A distribution-free detection procedure for a multiplerange-bin radar is described. This procedure is based on the ranks of observations, but does not require elaborate equipment for rapidly ranking large amounts of data. Proposed equipment is described and analysis and results are given comparing this new procedure with certain practical (nondistribution-free) procedures. Comparisons with some "best" theoretical procedures are also given.     

Observability Criteria for Bearings-Only Target Motion Analysis

The observability requirements for bearings-only target motion analysis (TMA) are rigorously established by solving a third-order nonlinear differential equation. Closed form expressions are developed and subsequently used to specify necessary and sufficient conditions on own-ship motion that insure a uniquetracking solution. It is shown that for certain types of maneuvers the estimation process remains unobservable, even when the associated bearing rate is nonzero. Such maneuvers are frequently overlooked in heuristic discussions of TMA observability, which may account for some common misconceptions regarding the characteristics of acceptable own-ship motion.     

Shock interactions in the outer heliosphere

Observations of plasma and magnetic fields by Pioneer 10 and 11 and Voyager 1 and 2 reveal that MHD shocks are an important component of the large-scale solar wind structures in the outer heliosphere. This review discusses recent progress in simulation studies of the nonlinear evolution of the solar wind structures, and in particular concentrates on the theoretical development and applications of the shock interactions model. Various stream propagation models, which do not use the Rankine-Hugoniot relations to calculate the jump conditions at shock crossings, have been used to simulate the essential evolution process of isolated streams and the formation and propagation of corotating and transient shocks. They produce fairly good results in the region up to a few AU. In 1984, the shock interactions model was introduced to study the evolution of large-scale solar wind structures in the region outside 1 AU up to several tens of AU. The model uses the exact Rankine-Hugoniot relations to calculate the shock speed and shock strength at all shock crossings. So that the model can more accurately calculate the shock speeds and the accumulated irreversible shock heating of plasma at several tens of AU. The applications of the shock interactions model are presented in three groups. (a) The first group covers the basic interaction of a shock with the ambient solar wind, the formation and propagation of shock pairs, and the collision and merging of shocks. (b) The second group covers the use of the shock interactions model to simulate the nonlinear evolution of large-scale solar wind structures in the outer heliosphere. These simulation results can provide the detailed evolution process for large-scale solar wind structures in the vast region not directly observed. Two selected studies are reported. (c) Finally, the shock interactions model is applied to studying the heating of the solar wind in the outer heliosphere. The model calculations support shocks being chiefly responsible for the heating of the solar wind plasma in the outer heliosphere at least up to 30 AU.     

Comments on the Cost and Performance of Military Systems

Editor's Note: Mr. Fowler was the banquet speaker at the Tri Service Radar Symposium held at West Point in 1977. We invited Mr. Fowl to share his speech with the AES readership by providing this paper. The material and style correspond closely to his oral presentation.