Route optimization of the aircraft flight

A method of finding the aircraft optimal route by means of task-oriented replacement of the functional being optimized is proposed.     

Applied potential tomography shows differential changes in fluid content of leg tissue layers in microgravity.

Absence of hydrostatic forces in the human cardiocirculatory system normally leads to an overall body fluid deficit. It was hypothesized that this is mainly due to a loss of interstitial fluid. An experiment was performed on board the Russian MIR station. Cuffs were positioned around both thighs and inflated up to suprasystolic values. This maneuver took place just before and after immediately a lower body negative pressure session (LBNP). The redistribution of fluids underneath the cuffs was assessed by means of cross-sectional impedance tomography (Applied Potential Tomography, APT). A microgravity induced loss of interstitial fluid was measured in all layers of the observed cross-section. The APT-readings changed significantly (SD approximately +/- .9) from 3.0 at 1g to 1.7 at 0g for the outer layer and from 2.7 at 1g to 2.0 at 0g for the middle layer (expressed in arbitrary units). The LBNP maneuver was able to fill the interstitial space but only at levels higher than -15 mmHg LBNP. This suggests that the superficial tissues in the legs are as much affected as the deeper ones by changing g-conditions and LBNP can be used to counteract interstitial fluid loss in this area.     

Sooting and disruption in spherically symmetrical combustion of decane droplets in air

Results of experiments are reported on the burning of individual decane droplets, initially between 1.0 and 1.2 mm in dia, in air at room temperature and atmospheric pressure. Use was made of the 2.2 s drop tower at the NASA Lewis Research Center and a newly designed droplet-combustion apparatus that promotes nearly spherically symmetrical combustion. Unanticipated disruptions were encountered and related to sooting behavior.     

The cataclysmic variable SS Cygni

In this work we will try to give the most general panorama, comparatively with the conciseness, on SS Cygni which is the brightest dwarf nova.The dwarf novae form a sub-class of the more vaste panorama of the Cataclysmic Variables (CVs). For this reason firstly we will describe in general the CVs and the current theories which attempt to describe their physical behaviour (Sections 2 and 3). The up-to-date observational properties of SS Cygni (Section 4) and a discussion on their explanation within the framework of theories (Section 5) will allow us to draw the conclusions (Section 6) and to argue the most convenient line of investigation (Section 7) both experimental and theoretical for a better understanding of the underlying physics of these systems.     

A novel way for the formation of alpha-amino acids and their derivatives in an aqueous medium.

In the course of a study of possible mechanism for chemical evolution in the primeval sea, we observed the formation of alpha-amino acids and N-acylamino acids from alpha-oxo acids and ammonia in an aqueous medium. Glyoxylic acid reacted with ammonia to form N-oxalylglycine, which gave glycine in a 5-39% yield after hydrolysis with 6N HCl. Similarly when glyoxylic acid was treated with methylamine it yielded N-oxalylsarcosine, which could be hydrolyzed to sarcosine with 17-25% overall yield upon hydrolysis. Pyruvic acid and ammonia reacted to give N-acetylalanine, which formed alanine in a 3-7% overall yield upon hydrolysis. The pH optima in these reactions were pH 3-4. These reactions were further extended to the formation of other amino acids. Glutamic acid, phenylalanine and serine were formed from alpha-ketoglutaric acid, phenylpyruvic acid and hydroxypyruvic acid, respectively, under similar conditions. N-Succinylglutamic acid was obtained as an intermediate for glutamic acid synthesis. Phenylacetylphenylalanineamide was also isolated as an intermediate for phenylalanine synthesis. Alanine, rather than aspartic acid, was produced from oxaloacetic acid. These reactions provide a novel route for the prebiotic synthesis of amino acids. A mechanism for the reactions is proposed.     

Proton flare and magnetic storm effect in the vicinity of the Earth.

We have developed a model and associated computational procedure for estimating energetic proton exposures during a major solar proton event that occur in combination with a large magnetic storm. Transmission functions for solar protons are computed using geomagnetic vertical cutoff data for quiescent and disturbed conditions. Predicted exposures in low altitude polar orbit are found to be orders of magnitude greater for severe magnetic storm conditions than are corresponding exposures in the absence of major disturbances. We examine the response scenario for the events of November 1960 as an example.     

Some practical strategies for reducing intermodulation in satellitecommunications

Various heuristic procedures for obtaining practical solutions to the general one-level carrier frequency assignment problem are described. The problem treated is general in the sense that it accommodates the case where L of the N slots may be explicitly designated as prohibited and unavailable for assignment. This problem occurs in satellite transmission with many small carriers accessing the same transponder where, due to multipath and TV interference from crosspolarized transponders of the same satellite and from copolarized transponders of the adjacent satellites, some portions of the bandwidth of the considered transponder cannot be used. To permit comparison with respect to the intermodulation advantage and central-processing-unit time required, the case without prohibited slots is considered. The sequential insertion procedure in which, starting with two carriers at the two end slots, one additional carrier at a time is optimally inserted into one of the unassigned slots is found best when the ratio between the available bandwidth and the total carrier bandwidth is greater than about 125%. All the heuristic procedures produced assignments whose intermodulation advantages are all greater than the bandwidth ratio     

Mixed graphic architecture for radar displays

The current state of the art in designing radar displays is first analyzed. An advanced architecture is proposed that overcomes the previous display limitations by using the mixed vector-raster concept. Design tradeoffs are identified, and feasible solutions are given. A simplified prototype that realizes these concepts is presented     

Algorithms for Power Converter Design Optimization

A practical optimization approach for power converters is established which allows conception of a design to meet all powercircuit performance requirements and concurrently to optimize a defined quantity such as weight or losses. In addition to facilitating a cost effective design, the computer-aided approach provides a means to readily assess a) the weight-efficiency tradeoff, b) impacts of converter requirements and component characteristics on a given design, and c) optimum power-system configurations. The following two popular algorithms for nonlinearly constrained optimization are utilized to design the power converter: 1) the sequential unconstrained minimization technique, SUMT Version 4; 2) the ALAG penalty function technique, ALAG5. These algorithms are compared, and suggestions are made for improving the efficiency of the optimization algorithms for power converter design.     

Composites for large space structures

A preliminary study of advanced composites and truss-type designs for application to large space structures is discussed. The benefits of advanced composite materials for large space structures and examples of large space structure design concepts and construction techniques are presented. Criteria are developed to guide the selection of structural elements, joints, and on-orbit fabrication techniques for truss-type structures and a ranking of candidate on-orbit fabrication techniques is accomplished in accordance with the criteria developed. On the basis of study results, recommended research and development goals for design, construction, and on-orbit fabrication of large space structures are established.