Effect of gravity on halocarbon flame retardant effectiveness

Flammability limits, burning velocities, and minimum ignition energies under initially quiescent conditions were measured for stoichiometric and fuel-lean methane-, ethane-, and propane-air mixtures containing varying concentrations of Halon 1301. The characteristics of near-limit flames were strongly affected by fuel type but not Halon concentration. The conclusions are that the mechanism of the flammability limits was affected by fuel type but not Halon concentration, that the cause of the zero-g flammability limits is mostly dependent on the molecular diffusion characteristics of the reactant gases and is mostly independent of chemical kinetics, and that the one-g upward flammability and ignition limits provide adequate criteria for safety at one-g and zero-g for both uninhibited and inhibited mixtures.     

Computer-Aided Design and Graphics Applied to the Study of Inductor-Energy -Storage Dc-to-Dc Electronic Power Converters

A series of nine programs are developed for the design of the inductors of single-winding flyback converters. Three converter types are considered: voltage step-up, current step-up, and voltage step-up/current step-up. For each of the converter types, three pulse modulators are considered: constant frequency, constant transistor on-time, and constant transistor off-time. Computer-graphics displays are used to assist in evaluating characteristics of the various converter-modulator combinations.     

Doppler scintillation measurements of the heliospheric current sheet and coronal streamers close to the Sun

Prominent enhancements in Doppler scintillation lasting a fraction of a day (solar source several degrees wide) and overlying the neutral line represent the signature of the heliospheric current sheet and the apparent interplanetary manifestation of coronal streamers near the Sun. This first detection of coronal streamers in radio scintillation measurements provides the link betweenin situ measurements of the spatial wavenumber spectrum of electron density fluctuations beyond 0.3 AU and earlier measurements deduced from radio scintillation and scattering observations inside 0.3 AU. Significant differences between the density spectra of fast streams and slow solar wind associated with the heliospheric current sheet near the Sun reinforce the emerging picture that high- and low-speed flows are organized by the large-scale solar magnetic field, and that while the contrast between solar wind properties of the two flows is highest near the Sun, it undergoes substantial erosion in the ecliptic plane as the solar wind expands.     

Dose rate and repair effects on cell damage in Earth orbit.

Radiobiology experiments performed in space will encounter continuous exposures to the cosmic rays and fractionated exposures to trapped protons which accumulate to several hundred dose fractions in a few weeks. Using models of track structure and cellular kinetics combined with models of the radiation environment and radiation transport, we consider calculations of damage rates for cell cultures. Analysis of the role of repair mechanisms for space exposures for the endpoints of survival and transformation is emphasized.     

The NASA Astrobiology Roadmap

The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities, and private institutions. The Roadmap addresses three basic questions: How does life begin and evolve, does life exist elsewhere in the universe, and what is the future of life on Earth and beyond? Seven Science Goals outline the following key domains of investigation: understanding the nature and distribution of habitable environments in the universe, exploring for habitable environments and life in our own solar system, understanding the emergence of life, determining how early life on Earth interacted and evolved with its changing environment, understanding the evolutionary mechanisms and environmental limits of life, determining the principles that will shape life in the future, and recognizing signatures of life on other worlds and on early Earth. For each of these goals, Science Objectives outline more specific high-priority efforts for the next 3-5 years. These 18 objectives are being integrated with NASA strategic planning.     

A new dynamical atmospheric ionizing radiation (AIR) model for epidemiological studies.

A new Atmospheric Ionizing Radiation (AIR) model is currently being developed for use in radiation dose evaluation in epidemiological studies targeted to atmospheric flight personnel such as civilian airlines crewmembers. The model will allow computing values for biologically relevant parameters, e.g. dose equivalent and effective dose, for individual flights from 1945. Each flight is described by its actual three dimensional flight profile, i.e. geographic coordinates and altitudes varying with time. Solar modulated primary particles are filtered with a new analytical fully angular dependent geomagnetic cut off rigidity model, as a function of latitude, longitude, arrival direction, altitude and time. The particle transport results have been obtained with a technique based on the three-dimensional Monte Carlo transport code FLUKA, with a special procedure to deal with HZE particles. Particle fluxes are transformed into dose-related quantities and then integrated all along the flight path to obtain the overall flight dose. Preliminary validations of the particle transport technique using data from the AIR Project ER-2 flight campaign of measurements are encouraging. Future efforts will deal with modeling of the effects of the aircraft structure as well as inclusion of solar particle events.     

Rocket borne electron accelerator results pertaining to the beam plasma discharge

Three flights of rocket borne electron accelerators have yielded some results concerning the Beam Plasma Discharge (BPD). The first flight, E||B, from Churchill carrying an accelerator of 2 and 4 keV electrons, produced a spectrum of whistler mode waves which was identical with that produced in a large vacuum chamber, and which we know to be an indicator of BPD. The second, Echo V, launched from Poker Flat, Alaska, carrying an accelerator of 25–35 keV electrons, produced wave emissions at 3–3.5 MHz observed on the ground. Our interpretation is that BPD was not or was weakly produced. In the third flight, NB³-II launched from Churchill with an accelerator of 2, 4 and 8 keV electrons, wave emissions well above the ambient plasma frequency were observed from a separated payload, but very close to the beam, and are interpreted as demonstrating BPD.     

Fundamental Unsolved Problems in Astrophysics

There is given a list and discussion of what are arguably the top 20 unsolved problems in astrophysics today. The list ranges from particle physics to cosmology. Possible resolutions are noted, but without judgement. Perhaps the most remarkable aspect of the discussed problems is that they are closely interrelated. This opens the prospect that a solution to one or a few may lead to a significantly better understanding of modern astrophysics.     

Search radar detection and track with the Hough transform. I.system concept

A method of viewing search radar signals and data is described and analyzed in which the image processing technique of the Hough transform is used to extract detections and simultaneous tracks from multi-dimensional data maps. System design concepts are considered and simulation examples are given that illustrate the concept. The technique offers many advantages when compared with more traditional techniques. These advantages include improved detection, a solution to the range walk problem, flexibility of implementation, elimination of slow scan-rate latency and automatic track acquisition without revisit. The concept is similar to track-before-detect algorithms that use preliminary information from previous scans to aid in target declarations