On the definition of the listing-geoid taking into consideration different height systems
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Lelgemann, D.↗
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Veterinary medical considerations for the use of nonhuman primates in space research
The validity of biomedical research using animal subjects is highly dependent on the use of 'normal' and healthy animals. The current costs of research programs dictate that a minimum number of animals and test replicates be used to obtain the desired data. The use of healthy and standardized animals increases the probability of obtaining valid data while also permitting greater economy by reducing the between-individual variation, thus allowing the use of fewer animals. Areas of concern when planning animal payloads include constraints of the flight on candidate species selection, screening for physiological and psychological normalcy, procedures for routine care and quarantine of new animals and those returning from space, ground-based studies to determine experimental protocol, selection of instrumentation, stress during transportation for flight operations, housing and care facilities at launch and recovery sites, and the overall veterinary program.
Simmonds, R. C.↗
Consideration of other primate species as flight animals
The different types of primates which might be used as flight animals are surveyed, and the pros and cons of using them are discussed. Various factors suggest that the most desirable animals for space studies are the rhesus, pig-tailed, Java, and squirrel monkeys. The capuchin monkey has assets for certain types of space experimentation.
Geoffrey H. Bourne↗
Design considerations in mechanical face seals for improved performance. 1: Basic configurations
Basic assembly configurations of the mechanical face seal are described and some advantages associated with each are listed. The various forms of seal components are illustrated, and functions pointed out. The technique of seal pressure balancing and its application are described; and the concept of the PV factor, its different forms and limitations are discussed. Brief attention is given to seal lubrication since it is covered in detail in a companion paper. Finally, the operating conditions for various applications of low pressure seals (aircraft transmissions) are listed, and the seal failure mode of a particular application is discussed.
Ludwig, L. P.↗
Considerations in the design of tip-coupled air-transport systems
It is shown that the lift-drag ratio of tip-coupled systems can be expressed as a simple multiple of the lift-drag ratio of the isolated units comprising the system. When operated for maximum lift-drag ratio, the extent of the coupled system is limited by maximum lift coefficient, high-altitude engine characteristics, and degraded performance of the isolated unit climbing to couple into the system. When operated at constant altitude, the gain from coupling is severely limited. If the cruise altitude is that for best performance of the isolated unit, the system lift-drag ratio can be no better than twice that of the isolated unit even when an infinite number of units are coupled. System performance may be further degraded since span-load distributions which yield good performance for the individual units reduce the efficiency of the coupled system. Coupling a pair of modern transport aircraft results in only about half the expected gain because of a poor span-distribution across the coupled pair. The control deflections required to maintain roll and pitch equilibrium further degrade the possible gain.
Heyson, H. H.↗
Piping design considerations in a solar-Rankine power plant
Two of the main parameters in sizing the piping of a solar power plant are the working pressure of the vapor leaving the solar collectors, and the type of working fluid used. Numerical examples for each case are given using the graphical Moody friction charts and the analytical Darcy-Weisbach equation. Different working pressures of steam vapor in the solar collector-turbine pipe connection indicate their major role in the design. The size variation was found not to be in linear proportion to vapor density variations. On the other hand, high molecular weight organic fluids such as R-11 and R-113, when compared with water, show insignificant changes in piping sizes.
Lansing, F. L.↗
Instability of a compressible circular free jet with consideration of the influence of the jet boundary layer thickness
The instability of a circular jet was investigated by means of the inviscid linearized stability theory. By variation of a jet parameter which takes the ratio of jet radius to boundary layer thickness into account, the influence of axisymmetry on the spatial growth rate and disturbance phase velocity is studied. The influence of Mach number and temperature ratio is discussed. A comparison with measurements shows that the instability of a turbulent jet boundary layer may also be explained by these results.
Michalke, A.↗
Considerations on coal gasification
Commercial processes for the gasification of coal with oxygen are discussed. The Koppers-Totzek process for the gasification of coal dust entrained in a stream of gasifying agents is described in particular detail. The outlook for future applications of coal gasification is presented.
Franzen, J. E.↗
Seakeeping considerations in the employment of V/STOL on Naval ships
Compatibility of Naval ships as V/STOL support platforms and the ship motions that V/STOL aircraft must endure are discussed. A methodology which evaluates the impact of motion criteria such as the maximum ship motion allowable during V/STOL landing/launch is presented. Emphasis is given to design alternatives that reduce ship motion.
Olson, S. R.↗
Considerations to achieve directionality for gamma ray lasers
A method of alignment of nuclei for a gamma ray laser and a means of achieving preferential emission of radiation along the crystal axis are studied. Atomic alignment was achieved by materials researchers who made composite structures composed of needle-like single crystals all with the same orientation and all pointing in the same direction contained in a matrix of cobalt or nickel. The proposed method of preferential emission of radiation along the aligned needles is to have a symmetric field gradient at the nucleus and a sequence of excited levels of spin and parity 2(+) and 0(+). The proposed scheme reduces the density of excited states required for lasing and reduces the linewidth due to inhomogenous broadening. Mossbauer absorption experiments intended to test these ideas are outlined.
Jha, S.↗
System considerations
Closing remarks and a general summary of the Alternative Energy Systems Seminar are presented. It was concluded from the seminar that the DOE programs described were focused on trying to make a commercial market develop for the various systems. The question addressed is how this is going to happen. To address this question, social, economical, political and technical aspects are considered with major emphasis placed on systems engineering to provide low cost efficient systems.
Alper, M. E.↗
Material and design considerations of encapsulants for photovoltaic arrays in terrestrial applications
Procedures for analyzing cyclic mechanical stresses in encapsulated photovoltaic arrays designed for terrestrial application are discussed. The concept of 'thermal stiffness', the product of alpha and Young's modulus, is presented, and its usefulness for minimizing mechanical stresses is demonstrated. The concept of the 'proportional-limit' helps indicate the upper limit of design stress for plastics. System design is considered with attention to cell dimensions, cell to substrate adhesive, single encapsulant system, double layer encapsulant, and stresses in the interconnects. The permeability of polymeric materials to gases is examined.
Carroll, W.↗
Interface design considerations for terrestrial solar cell modules
The need for increased solar array electrical efficiency and reliability in the achievement of future large-scale system cost goals is discussed. The relative performance of various array module designs currently on the market is evaluated, and further design improvements are suggested. The subjects of module efficiency, temperature control, and series/parallel reliability are analyzed. Applications for various combinations of array characteristics are considered.
Ross, R. G., Jr.↗
Electric vehicle power train instrumentation - Some constraints and considerations
The application of pulse modulation control (choppers) to dc motors creates unique instrumentation problems. In particular, the high-harmonic components contained in the current waveforms require frequency-response accommodations not normally considered in dc instrumentation. In addition to current sensing, accurate power measurement not only requires adequate frequency response but also must address phase errors caused by the finite bandwidths and component characteristics involved. This paper discusses the implications of these problems and reports on the degree to which they have been solved at Lewis Research Center.
Triner, J. E.↗
Radiation protection design considerations for man in geosynchronous orbits
A description is presented of preliminary studies which have been carried out to identify design requirements and mission constraints imposed by the geosynchronous radiation environment. The radiation species of dominant impact are the trapped electrons and solar flare particles. The criterion used in the conducted shielding design analysis has been to limit the skin dose to 100 rems for 3 months. The analysis included the optimization of an electron/bremsstrahlung shield for residence within the vehicle, the minimization of the dose received in extravehicular activity, and the calculation of special shield requirements for solar flares. An investigation was conducted of the potential benefits accruing from a three-layered composite shield with part of the aluminum layer replaced with a lower atomic number material. The materials considered were polyethylene, carbon, beryllium, and lithium hydride.
Rossi, M. L.↗
Design consideration for a nuclear electric propulsion system
A study is currently underway to design a nuclear electric propulsion vehicle capable of performing detailed exploration of the outer-planets. Primary emphasis is on the power subsystem. Secondary emphasis includes integration into a spacecraft, and integration with the thrust subsystem and science package or payload. The results of several design iterations indicate an all-heat-pipe system offers greater reliability, elimination of many technology development areas and a specific weight of under 20 kg/kWe at the 400 kWe power level. The system is compatible with a single Shuttle launch and provides greater safety than could be obtained with designs using pumped liquid metal cooling. Two configurations, one with the reactor and power conversion forward on the spacecraft with the ion engines aft and the other with reactor, power conversion and ion engines aft were selected as dual baseline designs based on minimum weight, minimum required technology development and maximum growth potential and flexibility.
Phillips, W. M.↗
Design considerations in mechanical face seals for improved performance. I - Basic configurations
Basic assembly configurations of the mechanical face seal are described and some advantages associated with each are listed. The various forms of seal components (the primary seal, secondary seal, etc.) are illustrated, and functions pointed out. The technique of seal pressure balancing and its application is described; and the concept of the PV factor, its different forms and limitations are discussed. Brief attention is given to seal lubrication since it is covered in detail in a companion paper. Finally, the operating conditions for various applications of low pressure seals (aircraft transmissions) are listed, and the seal failure mode of a particular application is discussed.
Ludwig, L. P.↗
Design considerations in mechanical face seals for improved performance. II - Lubrication
The importance of sealing technology in the U.S. industrial chemical-orientated society in regard to maintenance and environmental contamination is pointed out. It is stated that seal performance (leakage, life) is directly related to seal lubrication, which is a mechanism not well understood. Current thinking in regard to seal lubrication is reviewed, the effect of energy dissipation in the thin lubricating film separating the sealing faces is pointed out, and the results of vaporization due to heating are illustrated. Also, hydrodynamic lubrication is reviewed, and an inherent tendency for the seal to operate with angular misalignment is pointed out. Recent work on hydrostatic effects is summarized and the conditions for seal instability are discussed. Four different modes of seal lubrication are postulated with the mode type being a strong function of speed and pressure.
Ludwig, L. P.↗