Study of physiological effects of weightlessness and artificial gravity in the flight of the biosatellite Cosmos-936.

In the 18.5-day flight of the Soviet biosatellite Cosmos-936 (3-22, August 1977) com-parative investigations of the physiological effects of prolonged weightlessness (20 rats) and artificial gravity of 1 g (10 rats) were carried out. Throughout the flight artificial gravity was generated by means of animal rotation in two centrifuges with a radius of 320mm. Postflight examination of animals and treatment of the flight data were performed by Soviet scientists in collaboration with the specialists from Bulgaria, Czechoslovakia, the German Democratic Republic, Hungary, Poland, Rumania, France and the U.S.A. During the flight the total motor activity of the weightless rats was higher and their body temperature was lower than those of the centrifuged animals. Postflight examination of the weightless rats showed a greater percentage of errors during maze an increase in water intake and a decrease in diuresis; a fall of the resistance of peripheral red cells; an increase in the conditionally pathogenic microflora in the mouth; a decrease of oxygen consumption, carbon dioxide production and energy expenditures; a drop in the static physical endurance; a decline in the capacity to keep balance on the rail; an increase in the latent period of the lifting reflex, etc. The centrifugal animals displayed lesser or no change of the above type. These findings together with the biochemical and morphological data give evidence that during and after flight adaptive processes in the centrifuged rats developed better.     

Simulation of DC spacecraft power systems

A modular state-variable approach is presented for DC spacecraft power system modeling and simulation. Each modular component is treated as a multiport network, and a state model is written with the port voltages as the inputs. The state model of a component is solved independently of the other components, using its state transition matrix. The state variables of each component are updated, assuming that the inputs are constant. Network analysis principles are then utilized to calculate the component inputs     

The X-ray background 2–50 kev: A superposition of known sources,or evidence of a new component?

The contribution of the canonical Quasars to the XRB 2–50 keV is not likely to exceed 50%. Nay, consideration of X-ray selection effects results in a further reduction of the value of sensible estimators for the intensity ratio L_X/L_O; in addition, recent counts of radioloud and radio-quiet Quasars definitely limit the number of faint sources. A missing component with definite spectral properties should comprise a sizeable fraction of the XRB.     

A Gaussian Mixture PHD Filter for Jump Markov System Models

The probability hypothesis density (PHD) filter is an attractive approach to tracking an unknown and time-varying number of targets in the presence of data association uncertainty, clutter, noise, and detection uncertainty. The PHD filter admits a closed-form solution for a linear Gaussian multi-target model. However, this model is not general enough to accommodate maneuvering targets that switch between several models. In this paper, we generalize the notion of linear jump Markov systems to the multiple target case to accommodate births, deaths, and switching dynamics. We then derive a closed-form solution to the PHD recursion for the proposed linear Gaussian jump Markov multi-target model. Based on this an efficient method for tracking multiple maneuvering targets that switch between a set of linear Gaussian models is developed. An analytic implementation of the PHD filter using statistical linear regression technique is also proposed for targets that switch between a set of nonlinear models. We demonstrate through simulations that the proposed PHD filters are effective in tracking multiple maneuvering targets.     

A methodology for addressing support equipment obsolescence

The rapid growth of technology over the last twenty years is providing vastly improved capabilities for both avionics and avionics test systems. Unfortunately, an environment of rapid technological growth breeds a corresponding environment of rapid technological obsolescence. Test systems developed fifteen years ago are becoming increasingly more difficult to support due to obsolescence issues and, additionally, such a test system does not reflect the current state-of-the-art for automatic test equipment. The ability of a test system to evolve is essential to providing cost-effective support systems for electronic systems. The F-15 Tactical Electronic Warfare System (TEWS) Intermediate Support System (TISS) was developed under the Modular Automatic Test Equipment (MATE) guidelines to support the suite of F-15 electronic warfare LRUs. MATE imposed hardware architecture constraints, which were factors that contributed to its abandonment. However, the modular aspect of MATE has provided a system that can easily evolve with technological advancements. Modularity is the cornerstone of modern software systems and this is the aspect that has been exploited in the evolution of the TISS     

Performance Analysis of the Modulation Cancellation Altimeter

The performance of the modulation cancellation altimeter is investigated. Several sources of error are considered, specifically: 1) terrain averaging error; 2) output noise fluctuations; 3) errors due to phase shifts; and 4) acquisition ambiguities. The predominant parameters affecting these errors are investigated with a view towards optimizing the performance of the altimeter.     

Prototype design and testing of a Venus long duration,high altitude balloon

This paper describes the design, fabrication and testing of a full scale prototype balloon intended for long duration flight in the upper atmosphere of Venus. The balloon is 5.5 m in diameter and is designed to carry a 45 kg payload at an altitude of 55 km. The balloon material is a 180 g/m² multi-component laminate comprised of the following layers bonded together from outside to inside: aluminized Teflon film, aluminized Mylar film, Vectran fabric and a polyurethane coating. This construction provides the required balloon functional characteristics of low gas permeability, sulfuric acid resistance and high strength for superpressure operation. The design burst superpressure is 39,200 Pa which is predicted to be 3.3 times the worst case value expected during flight at the highest solar irradiance in the mission profile. The prototype is constructed from 16 gores with bi-taped seams employing a sulfuric acid resistant adhesive on the outside. Material coupon tests were performed to evaluate the optical and mechanical characteristics of the laminate. These were followed by full prototype tests for inflation, leakage and sulfuric acid tolerance. The results confirmed the suitability of this balloon design for use at Venus in a long duration mission. The various data are presented and the implications for mission design and operation are discussed.