Fluorescent probes of biological membranes
Fluorescent probes inserted into biological membranes for molecular structural and dynamic facets
Stryer, L.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Heat transfer and thermal stratification in the Apollo 14 cryogenic oxygen tanks
Two significant facets of Apollo oxygen tank operation are the occurrence of thermal stratification at high fluid densities and the tendency toward high heater temperatures at low fluid densities. Some insight into the nature of these phenomena can be gained, respectively, by consideration of a two fluid stratification model and a conductive heat transfer model. The alternative of convective blowdown tank operation at low densities is briefly examined.
Fineblum, S. S.↗
Two Phase Detonation Studies Conducted in 1971
The research covered by this third annual progress report represents a continuation of our efforts devoted to the study of detonation waves in liquid-gas systems. The motivation for the work is associated with liquid propellant rocket motor combustion instability although certainly the studies are also applicable to internal combustion engines, jet propulsion engines, safety aspects of spilled liquid fuel, coal mine explosions, and weaponry. The research has been divided into 5 phases, although all of them are intimately related. For the most part these phases are briefly summarized and the reader is referred to other publications for a more complete treatment. The exception to this is where the material herein represents the only printed information available on the particular facet of the problem. Phase A has been primarily concerned with the breakup and ignition of fuel drops by shock waves. The experimental portion of this study as well as a theoretical treatment of the ignition behavior was completed in the past year. The research is now concentrating on the passage of a shock wave over a burning drop. Phase B has been devoted to the assessment of the approximate energy release pattern in two phase detonations insofar as they affect the significant overpressures observed.
Nicholls, J. A.↗
Sensor lighting considerations for earth observatory satellite missions
Facets of sensor lighting conditions for Earth observatory satellite missions are considered. Assuming onboard sensors of a given width viewing perpendicular to the subsatellite ground track along sun-synchronous orbits with various nodes, the ground trace of the ends of the sensor coverage were found, as well as the variation in solar illumination on the ground across the line covered by the sensor during the day for any point along the orbit. The changes with season and variation during the year were also found.
Cooley, J. L.↗
A study of an advanced confined linear energy source
A literature survey and a test program to develop and evaluate an advanced confined linear energy source were conducted. The advanced confined linear energy source is an explosive or pyrotechnic X-Cord (mild detonating fuse) supported inside a confining tube capable of being hermetically sealed and retaining all products of combustion. The energy released by initiation of the X-Cord is transmitted through the support material to the walls of the confining tube causing an appreciable change in cross sectional configuration and expansion of the tube. When located in an assembly that can accept and use the energy of the tube expansion, useful work is accomplished through fracture of a structure, movement of a load, reposition of a pin, release of a restraint, or similar action. The tube assembly imparts that energy without release of debris or gases from the device itself. This facet of the function is important to the protection of men or equipment located in close proximity to the system during the time of function.
Anderson, M. C.↗
Propagation of the transverse normal stress in a thick plate due to distributed lateral impulsive loadings
A theoretical study of the elastic stresses produced in an infinite plate when struck by a high-speed object is presented. The solution is obtained by means of linear elasticity. Laplace transformation techniques are employed to solve the axisymmetric problem. The plate is loaded normal to its surface with a uniform load over a circular area. The normal stress at the wave front of the unreflected dilatation wave along the axis and its variation with the radius of loading are determined. Various facets of the problem are discussed.
Oline, L. W.↗
Postulation of the arc restrike mechanisms for exploding wires and tubes.
The many facets of exploding wire restrikes are studied. They are related to the cylindrical shock wave which pumps down the density of the center region of a line energy source or around the surface of the heated wire continuously to a lower density. When the density of any region is pumped down to lower than Paschen's electric breakdown criteria, restrike occurs. The cylindrical shocks occurring in exploding wires are, in general, divided into two types. In the first type the shock is generated by the wire explosion and in the second type the shock is generated by the heat conduction of the wire to the surrounding gas. Application of this mechanism to exploding tubes will enable us to create arc channels in arbitrary gaseous atmospheres with controllable plasma density with the contamination excluded. Neutral density shielded plasma experiments, therefore, can be conducted in a controllable environment.
Cheng, D. Y.↗
Estimating trajectory correction requirements for the Outer Planets Grand Tour missions.
The estimation of trajectory correction requirements for the Outer Planets Grand Tour (OPGT) missions poses a unique and many-faceted problem for the systems analyst. In this paper the navigation concept for the OPGT is developed and illustrated. The limiting accuracies and performance of the combined radio/onboard optical system are examined. The combined orbit determination system is characterized by its accuracy and by its system risks. Such considerations are included with the statistical combination of maneuver estimates to produce preliminary delta V estimates for the planned OPGT missions.
Friedman, L. D.↗
Application of finite-element method in the computation of temperature with emphasis on radiative exchanges.
Analyses pertaining to the solution of heat transfer problems in combined modes based on the finite-element method are presented. Two elements - a triangular element employing two spatial variables and a multi-faceted bar element employing one spatial variable - with nonlinear radiation on the boundaries are detailed. The radiative effects considered on the diffuse-gray surface elements include: (1) directional radiant fluxes from distant sources, (2) radiative exchanges including surfaces of prescribed temperatures, and (3) radiative exchanges including elements whose temperatures are not known a priori. The nonlinear part of the boundary condition is treated in two different ways: (1) a consistent linearization method, and (2) a direct energy distribution method. Applications of these elements together with solution algorithms to three sample problems exhibit solution capability and obtainable accuracy.
Lee, H.-P.↗
Logistics hardware and services control system
Software system permits onsite direct control of logistics operations, which include spare parts, initial installation, tool control, and repairable parts status and control, through all facets of operations. System integrates logistics actions and controls receipts, issues, loans, repairs, fabrications, and modifications and assets in predicting and allocating logistics parts and services effectively.
Koromilas, A.↗
Apollo experience report: Consumables budgeting
The procedures and techniques used in predicting the consumables usage for the Apollo mission are discussed. Because of the many interfaces and influences on the consumables system, it is impractical to document all facets of consumables budgeting; therefore, information in this report is limited to the major contributions to the formulation of a consumables budget.
Nelson, D. A.↗
Monopropellant hydrazine resistoject: Engineering model fabrication and test task
The monopropellant hydrazine resistojet, termed the electrothermal hydrazine thruster (EHT) by TRW systems, thermally decomposes anhydrous hydrazine propellant to produce a high-temperature, low-molecular-weight gas for expulsion through a propulsive nozzle. The EHT developed for this program required about 3-5 watts of electrical power and produced 0.020 to 0.070 pound of thrust over the inlet pressure range of 100 to 400 psia. The thruster was designed for both pulsed and steady state operation. A summary of the GSFC original requirements and GSFC modified requirements, and the performance of the engineering model EHT is given. The experimental program leading to the engineering model EHT design, modifications necessary to achieve the required thruster life capability, and the results of the life test prgram. Other facets of the program, including analyses, preliminary design, specifications, data correlation, and recommendations for a flight model are discussed.
Murch, C. K.↗
Determinants of Market Structure and the Airline Industry
The general economic determinants of market structure are outlined with special reference to the airline industry. Included are the following facets: absolute size of firms; distributions of firms by size; concentration; entry barriers; product and service differentiation; diversification; degrees of competition; vertical integration; market boundaries; and economies of scale. Also examined are the static and dynamic properties of market structure in terms of mergers, government policies, and economic growth conditions.
Raduchel, W.↗
Video-to-film color-image recorder.
A precision video-to-film recorder for use in image data processing systems, being developed for NASA, will convert three video input signals (red, blue, green) into a single full-color light beam for image recording on color film. Argon ion and krypton lasers are used to produce three spectral lines which are independently modulated by the appropriate video signals, combined into a single full-color light beam, and swept over the recording film in a raster format for image recording. A rotating multi-faceted spinner mounted on a translating carriage generates the raster, and an annotation head is used to record up to 512 alphanumeric characters in a designated area outside the image area.
Montuori, J. S.↗
Study of dynamics of X-14B VTOL aircraft
Research was initiated to investigate certain facets of modern control theory and their integration with a digital computer to provide a tractable flight control system for a VTOL aircraft. Since the hover mode is the most demanding phase in the operation of a VTOL aircraft, the research efforts were concentrated in this mode of aircraft operation. Research work on three different aspects of the operation of the X-14B VTOL aircraft is discussed. A general theory for optimal, prespecified, closed-loop control is developed. The ultimate goal was optimal decoupling of the modes of the VTOL aircraft to simplify the pilot's task of handling the aircraft. Modern control theory is used to design deterministic state estimators which provide state variables not measured directly, but which are needed for state variable feedback control. The effect of atmospheric turbulence on the X-14B is investigated. A maximum magnitude gust envelope within which the aircraft could operate stably with the available control power is determined.
Loscutoff, W. V.↗
Steady state growth and segregation under zero gravity: InSb
It was established that ideal diffusion controlled steady state conditions, never accomplished on earth, were achieved during the growth of Te-doped InSb crystals in Skylab. Surface tension effects were found to establish non-wetting conditions under which free surface solidification took place in confined geometry. It was further found that, under forced contact conditions, surface tension effects led to the formation of surface ridges (not previously observed on earth) which isolated the growth system from its container. In addition, it was possible for the first time to identify unambiguously: the origin of segregation discontinuities associated with facet growth, the mode of nucleation and propagation or rotational twin boundaries, and the specific effect of mechanical-shock perturbations on segregation. The results obtained prove the advantageous conditions provided by outer space. Thus, fundamental data on solidification thought to be unattainable because of gravity induced interference on earth are now within reach.
Witt, A. F.↗
Assessment of a wake vortex flight test program
A proposed flight test program to measure the characteristics of wake vortices behind a T-33 aircraft was investigated. A number of facets of the flight tests were examined to define the parameters to be measured, the anticipated vortex characteristics, the mutual interference between the probe aircraft and the wake, the response of certain instruments to be used in obtaining measurements, the effect of condensation on the wake vortices, and methods of data reduction. Recommendations made as a result of the investigation are presented.
Spangler, S. B.↗
Convection and magnetic fields in an atmosphere with constant temperature gradient. I - Hydrodynamic flows
In order to deduce the fluid and field conditions deep in the supergranules from the fluid motions and magnetic fields observed in the solar photosphere, it is necessary to have some idea of the depth to which the supergranules extend and the form of their internal fluid velocities. Toward this end a number of analytic solutions of the Navier-Stokes equations are given for circumstances possessing various facets of the supergranule environment in the sun. These solutions, together with the earlier work by others, shows that the granules extend to depths in excess of their mean diameters, that the convective velocities probably do not diminish much, if any, with depth, and that across the tops of the supergranules at the photosphere the horizontal velocity is more or less independent of depth.
Parker, E. N.↗