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  • Chemical Engineering  (35)
  • FLUID MECHANICS AND HEAT TRANSFER  (35)
  • Fisheries
  • GENERAL
  • Inorganic Chemistry
  • 1990-1994
  • 1975-1979  (102)
  • 1955-1959
  • 1977  (102)
Collection
Publisher
Years
  • 1990-1994
  • 1975-1979  (102)
  • 1955-1959
Year
  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 657-665 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Five glass bead-filled polypropylene composites were rheologically characterized at 240°C using two rotational rheometers to obtain low shear-rate data and a capillary rheometer to obtain high shear-rate data. Both steady and dynamic properties were measured at low shear rates. Each composite was also injection molded into tensile and flexural test bars for a mechanical properties profile at 25°C. The tensile modulus was determined from a simple extensional deformation whereas the flexural modulus was determined from a three-point-bend test.The relative shear viscosity and relative loss modulus are different nonlinear functions of the volume fraction of beads at a constant shear rate, while the relative storage modulus appears to be a linear function of bead fraction. The relative viscosity decreases with increasing shear rate and the zero shear-rate data are in very good agreement with the Guth-Gold equation.The relative tensile modulus and relative flexural modulus are each linear functions of bead fraction over the entire range of filler concentration, 0-29 vol percent. From these data it is concluded that a simple correspondence between slow viscous flow and small strain elasticity does not exist for these composites.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 724-727 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mechanistic origins of the post extrusion swelling phenomenon have been the subject of considerable debate. Conflicting theories have postulated that it is caused either by (1) deformations at the die entrance which are recovered upon die exit as a consequence of viscoelastic memory or (2) elastic enorgy, which is stored during capillary flow by the action of normal stress, and subsequently released upon die exit or by both (1) and (2). We have described these situations by mathematical models and show that the resulting equations are similar despite different origins. The difficulties in interpreting the results mechanistically are discussed. Empirically, the results can be described as being exponential in capillary residence irrespective of cause.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 440-449 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The, nature of polymer surfaces has received increasing attention as the use of these materials, in a variety of forms, increases yearly. Modifications of polymer surfaces for adhesion, friction, and diffusion oriented appiications have necessitated a careful analysis of the surfade region morphology (surface physics) and chemical properties of the surface layer (surface chemistry). The behavior of composite structures has involved the discipline of classical fracture mechanics. The orientation of polymeric species or additives which migrate to the interface may modify the wetting characteristics and, most certainly, the frictional properties in addition to the diffusion of penetrant species beyond the boundary layer. The above topics are discussed within the framework of recent analytical and theoretical developments in surface science. The findings of these recent studies have facilitated many exciting technological advances.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Catalysis of Ammonia Synthesis and Nitrogen Isotope Exchange by Lamellar Compounds of Graphite with Iron, Ruthenium, and OsmiumThe catalytic activity of transition metal potassium-graphite lamellar compounds for the synthesis of ammonia from the elements and the catalysis of the equilibration by isotope exchange of the isotopic nitrogen molecules are shown to correlate. Connections between the state of metal in the catalyst exist with iron as metal which is shown by Mössbauer spectroscopy and the catalytic activity in relation to the potassium content.
    Notes: Die katalytische Aktivität von Übergangsmetall-Kalium-Graphitverbindungen bei der Synthese von Ammoniak aus den Elementen und bei der Einstellung des Isotopenaustauschgleichgewichts der isotopen Stickstoffmolekeln korrelieren miteinander. Im Falle von Eisen als Metall sind Beziehungen zwischen dem durch Mößbauer-Spektroskopie ermittelten Zustand des Metalls im Katalysator und der katalytischen Aktivität in Abhängigkeit vom Kaliumgehalt erkennbar.
    Additional Material: 3 Ill.
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  • 5
    Publication Date: 2019-07-13
    Description: The status of the continuing compliant wall drag reduction research at NASA-Langley Research Center is discussed. Preliminary surface motion calculations are reported along with compliant surface design concepts and their numerical models. A compliant drag reduction theory based on stabilizing the turbulent substructure is proposed and previous experiments have been examined relative to that theory. Results of recent low speed compliant surface experiments have been reported which include initial attempts to measure local compliant surface motion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Biennial Symposium on Turbulence in liquids; Sep 22, 1975 - Sep 24, 1975; Rolla, MO
    Format: text
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  • 6
    Publication Date: 2019-06-27
    Description: The preliminary feasibility of remote high-resolution infrared imagery of the space shuttle orbiter lower surface during entry to obtain accurate measurements of aerodynamic heat transfer to that vehicle was examined. In general, it was determined that such such images can be taken from an existing aircraft/telescope system (the C-141 AIRO) with a minimum modification or addition of systems using available technology. These images will have a spatial resolution of about 0.3 m and a temperature resolution much better than 2.5 percent. The data from these images will be at conditions and at a scale not reproducible in ground based facilities and should aid in the reduction of the prudent factors of safety required to account for phenomenological uncertainties on the thermal protection system design. Principal phenomena to be observed include laminar heating, boundary-layer transition, turbulent heating, surface catalysis, and flow separation and reattachment.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-73251 , A-6995
    Format: application/pdf
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  • 7
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Di-p-hydrido-bis[1,3-propanbis(dicyclohexylphosphin)]dinickel(Ni—Ni) - Der Bindungszustand in einem Dreizentren-Wasserstoff-überbrückten Ni—Ni-SystemDie Kristallstruktur der Titelverbindung [(C6H11)2PCH2CH2CH2P(C6H11)2NiH]2 (1) wurde aus 4051 Reflexen abgeleitet und zu einem R-Wert von 0.044 verfeinert. Lageparameter aller Wasserstoffatome konnten einer Differenz-Fourier-Synthese entnommen werden. Die Struktur der diamagnetischen Verbindung setzt sich aus zwei P2Ni-Untereinheiten zusammen, welche zweifach mit Wasserstoffatomen (Ni—H 1.6 Å) überbrückt sind. Hierdurch ergibt sich ein bindender Ni—Ni-Abstand von 2.441(1) Å. Im Kristallgitter bilden die Ebenen durch die P2Ni-Untereinheiten einen Interplanarwinkel von 63.3°. Theoretische Betrachtungen sagen für das freie Molekül eine quadratisch planare Anordnung voraus, doch ergibt sich für die Drehbewegung zur beobachteten Geometrie nur eine flache Potentialenergiefläche. Die gefundene Verdrillung resultiert aus starken intramolekularen Abstoßungskräften zwischen den Cyclohexylgruppen der zwei P2Ni-Einheiten.
    Notes: The crystal structure of the title compound, [(C6H11)2PCH2CH2CH2P(C6H11)2NiH]2 (1), has been determined from 4051 reflections and refined to a final R-value of 0.044. The positions of the hydrogen atoms (bridging and non-bridging) have been determined from a difference Fourier synthesis. The molecular structure of the diamagnetic compound consists of subunits doubly-bridged by hydrogen atoms. The Ni—Ni and average Ni—H distances are 2.441 and 1.6 Å, respectively. In the solid state the two planes of the P2Ni units form a dihedral angle of 63.3°. Theoretical considerations predict a square-planar structure for the idealized molecule with a soft potential energy surface for a twisting motion towards the observed geometry. The observed twist is the result of severe intramolecular repulsions between the cyclohexyl groups of the two P2Ni units.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 23 (1977), S. 177-184 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Diffusional mass transfer across membranes with uniform but low pore densities was studied experimentally as a function of stirring rate and pore area fraction. The results were analyzed in terms of a stagnant film boundary-layer model specially formulated for a heterogeneous membrane containing discrete pores. The overall membrane diffusional resistance is linearly related to the inverse of the pore area fraction of the membranes for a constant stirring rate. An equivalent boundary-layer thickness can be defined which is independent of membrane properties but a unique function of stirrer speed. These experimental boundary-layer thicknesses are greater by a factor of 3 than those predicted by a published Sherwood number correlation determined for homogeneous surfaces, but the stirring rate dependence is in excellent agreement with this same correlation.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 23 (1977), S. 816-822 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Process synthesis involves manipulation of the process arrangement, while studying the variables of each arrangement, to arrive at the optimal process. If each process arrangement is treated as a discrete variable, process synthesis becomes a mixed integer optimization problem. This paper examines the synthesis of heat exchanger networks using the adaptive random search procedure, which can be used to search continuous and discrete independent variables simultaneously. The means of handling the heat exchanger arrangement as a discrete variable is discussed, and the incorporation of various synthesis heuristics is presented. The results of synthesis of 2 × 2, 2 × 3, and 3 × 3 networks are presented and compared with other methods of synthesis.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 23 (1977), S. 602-604 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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