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  • Chemical Engineering  (325)
  • Life and Medical Sciences  (210)
  • FLUID MECHANICS AND HEAT TRANSFER  (180)
  • Biology
  • GENERAL
  • General Chemistry
  • 1975-1979  (710)
  • 1955-1959  (174)
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  • 1
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    A comparison of the Method of Lines to finite difference techniques in solving time-dependent partial differential equations (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Steady state solutions to two time dependent partial differential systems have been obtained by the Method of Lines (MOL) and compared to those obtained by efficient standard finite difference methods: (1) Burger's equation over a finite space domain by a forward time central space explicit method, and (2) the stream function - vorticity form of viscous incompressible fluid flow in a square cavity by an alternating direction implicit (ADI) method. The standard techniques were far more computationally efficient when applicable. In the second example, converged solutions at very high Reynolds numbers were obtained by MOL, whereas solution by ADI was either unattainable or impractical. With regard to 'set up' time, solution by MOL is an attractive alternative to techniques with complicated algorithms, as much of the programming difficulty is eliminated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computers and Fluids; 6; June 197
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Evaluation of a large capacity heat pump concept for active cooling of hypersonic aircraft structure (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Results of engineering analyses assessing the conceptual feasibility of a large capacity heat pump for enhancing active cooling of hypersonic aircraft structure are presented. A unique heat pump arrangement which permits cooling the structure of a Mach 6 transport to aluminum temperatures without the aid of thermal shielding is described. The selected concept is compatible with the use of conventional refrigerants, with Freon R-11 selected as the preferred refrigerant. Condenser temperatures were limited to levels compatible with the use of conventional refrigerants by incorporating a unique multipass condenser design, which extracts mechanical energy from the hydrogen fuel, prior to each subsequent pass through the condenser. Results show that it is technically feasible to use a large capacity heat pump in lieu of external shielding. Additional analyses are required to optimally apply this concept.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-145301
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    An experimental and computational investigation of the flow field about a transonic airfoil in supercritical flow with turbulent boundary-layer separation (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A combined experimental and computational research program is described for testing and guiding turbulence modeling within regions of separation induced by shock waves incident in turbulent boundary layers. Specifically, studies are made of the separated flow the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include highfrequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-X-73157 , A-6690
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
    Electronic Resource
    Electronic Resource
    Mechanics of the syrinx in Gallus gallus. II. Electromyographic studies of Ad Libitum vocalizations (1977)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 152 (1977), S. 1-19 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Records of electrical activity in the tracheal muscles of domestic chickens were obtained for a variety of ad libitum vocalizations. Primary attention was given to an analysis of events during the most complex call, crowing.Three pairs of muscles, Mm. tracheohyoideus, tracheolateralis, and sternotrachealis, can affect the configuration of a chicken's syrinx. The firing patterns of the three muscle pairs are related to their different abilities to affect the tension of the syringeal membranes. The influence of M. tracheohyoideus is most indirect and imprecise, and its role the least clearly defined. It appears to adjust the position of the trachea so that the syrinx is isolated from unpredictable and/or undesirable consequences of nuchal position and tracheal elasticity, and also helps draw the glottis caudad, thereby deepening the pharyngeal chamber. The other two muscles interact to control the tension of the vocal membranes. M. sternotrachealis relaxes the membranes by drawing the drum of the trachea caudad, or, via the syringeal ligament, by rotating the pessulus cranioventrad, or both. M. tracheolateralis tenses the membranes and/or prevents caudal movement of the origin of M. sternotrachealis, a necessity if the syringeal ligament is to rotate the pessulus.Vocalization depends on both syringeal configuration and appropriate air flow. Hence, tracheal muscles, syrinx, air sacs, and ventilatory muscles cooperate to form a vocal system. Cooperation elicits a surprising degree of redundancy. At least one call, a high pitched wail, may be produced by two very different techniques.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051520102
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Drop size distributions and coalescence frequencies of liquid-liquid dispersions in flow vessels (1976)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 22 (1976), S. 289-297 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A flash photomicrographic method and modified dye-light transmittance technique are employed to measure size distributions and mixing frequencies in a turbulently agitated flow vessel. This liquid-liquid dispersion is nearly spatially homogenous. Mixing frequencies are strongly dependent on impeller speed and moderately dependent on holdup fraction.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690220211
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  • 6
    Electronic Resource
    Electronic Resource
    An examination of the adaptive random search technique (1976)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 22 (1976), S. 744-750 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Random search procedures have recently been successfully applied to the optimization of a variety of chemical engineering problems, including optimization of chemical processes by flow sheet simulation. These procedures represent the independent variables as random variables described by probability distributions. The adaptive random search procedure centers the distribution for each variable about the best search point found and examines this region for a better point. Thus, this technique has the ability of continuously moving the search region toward the optimum, which is particularly advantageous in following constraints.This study examines the efficiency of the adaptive random search technique as applied to six different problems, which have been previously solved by various other techniques.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690220417
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  • 7
    Electronic Resource
    Electronic Resource
    Denitrification kinetics in packed beds (1976)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 22 (1976), S. 851-855 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bench scale packed columns were used to study the kinetic behavior of biological denitrification. After tracer studies were run to determine flow characteristics, steady state nitrate profiles were determined. A first-order rate expression with an Arrhenius temperature dependence is an adequate model of the reaction for nitrate-nitrogen concentrations of 〈 100 mg/l and temperature of 5° to 20°C. The rate constants are proportional to the packing surface area.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690220506
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  • 8
    Electronic Resource
    Electronic Resource
    Vapor-liquid equilibria for hydrogen-light-hydrocarbon systems at low temperatures (1957)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 3 (1957), S. 33-36 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental equilibrium vapor and liquid compositions are reported for the hydrogen-methane system at -150°, -200°, and -250°F. and at pressures of 500 to 4,000 lb./sq. in. The ternary system hydrogen-methane-propane was studied at 0°, -100°, and -200°F. at 500 and 1,000 lb./sq. in. Phase compositions were determined for a limited number of similar conditions for the hydrogen-methane-propylene and hydrogen-methane-ethylene-ethane-propylene-propane systems.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690030107
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  • 9
    Electronic Resource
    Electronic Resource
    On phase equilibrium at the gas-liquid interface during absorption (1958)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 439-444 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: That phase equilibrium exists at the gas-liquid interface during gas absorption is usually assumed in the analysis and design of absorption equipment, but the validity of this assumption has been in doubt since Higbie's pioneering gas-absorption studies. Accurate measurements are reported herein of the absorption rates at 25°C. of carbon dioxide into short water jets in which the liquid was in laminar flow. The jets issued from circular nozzles of about 1.5-mm. diam., flowed intact downward through an atmosphere of carbon dioxide at average velocities of from 75 to 550 cm./sec. over distances of 1 to 15 cm., and were collected in a receiver slightly larger in diameter than the nozzles. The measured absorption rates are in excellent agreement with predictions based on unsteady state diffusion theory, when one assumes interfacial equilibrium. It is concluded from these results and those of other investigators that equilibrium prevails at a freshly formed, relatively clean, carbon dioxide-water interface and that the same statement probably applies to the absorption of other slightly soluble gases in water.Evidence is discussed which indicates that an accumulation of minute quantitities of surface-active materials may seriously reduce the rate of gas absorption, either by affecting the hydrodynamic characteristics of the system or perhaps by offering resistance to the transfer of solute molecules across the interface.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690040412
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  • 10
    Electronic Resource
    Electronic Resource
    Ion exchange separation of gram quantities of americium from a kilogram of lanthanum (1957)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 3 (1957), S. 286-288 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The separation of 4.5 g. of americium from approximately a kilogram of light rare earths (primarily lanthanum) was achieved on a pilot plant scale by chromatographic displacement of the mixture from Dowex-50 resin with 0.1% ammonium citrate at pH 8 into hydrogen-form Dowex-50. The americium collected into a narrow band and was eluted free from lanthanum but contained an equal weight of cerium. A 6- and a 2-in.-diam. column were used in tandem. Use of a final column with a much smaller diameter would have permitted a cleaner separation from cerium, but this was left for a laboratory-scale separation by a different process. Precipitation, which was observed in the columns during the first runs, was later avoided entriely by use of high flow rates both initially and during the transfer between columns. No adverse effects were noted from ∼15 curies of alpha activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690030228
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