Showing papers by "Karlsruhe Institute of Technology published in 1977"

Heat and Mass Transfer between Impinging Gas Jets and Solid Surfaces

Abstract: Publisher Summary Heating or cooling of large surface area products is often carried out in devices consisting of arrays of round or slot nozzles, through which air impinges vertically upon the product surface. This chapter presents a comprehensive survey emphasizing the engineering applications and empirical equations, presented for the prediction of heat and mass transfer coefficients within a large and technologically important range of variables. The local variations of the transfer coefficients are based on the experimental data for single round nozzles (SRN), arrays of round nozzles (ARN), single slot nozzles (SSN), and arrays of slot nozzles (ASN). The variation of local transfer coefficients is graphically represented. It also explores how to apply these equations in heat exchanger and dryer design as well as in optimization. The flow field of impinging flow is diagrammatically represented. External variables influencing heat and mass transfer in impinging flow depends on mass flow rate, kind and state of the gas and on the shape, size, and position of the nozzles relative to each other and to the solid surface. The design of high-performance arrays of nozzles is also discussed.

Herstellung von Hilfsstoffen für die asymmetrische Synthese aus Weinsäure. Addition von Butyllithium an Aldehyde in chiralem Medium

Abstract: Preparation of Auxiliaries for Asymmetric Syntheses from Tartaric Acid. Additions of Butyllithium to Aldehydes in Chiral Media. Chiral derivatives of the complexing 1,2-diheterosubstituted ethanes A–D are prepared from tartaric acid. The key starting materials are the succinic acid derivative 1, the dioxolane 2a, and the diamide 3a. These are converted to the ethers, alkoxyamines, and alkylthio-amines listed in the first column of Table 2 which also contains the derivatives 21c, 22d, and 23d made from lactic acid, malic acid, and proline, respectively. It is shown that the highest optical yields (up to 40%) in reactions of butyllithium with aldehydes are obtained when mixtures of (−)-1,2,3,4-tetramethoxy-butane (4b), (+)-2,3-dimethoxy-N,N,N′,N′-tetramethyl-1,4-butanediamine (17a), and (−)-1,4-dimethoxy-N,N,N′,N′-tetramethyl-2,3-butanediamine (14c) with pentane are used at temperatures down to −150° and ratios of auxiliary/butyllithium of up to 10:1 (see equation (1), Tables 2–4).

Seismic anisotropy of the subcrustal lithosphere as evidence for dynamical processes in the upper mantle

Abstract: Summary. Anisotropy of seismic waves in the uppermost mantle has not only been observed in the oceanic but recently also in the continental lithosphere. Laboratory experiments on the formation of preferred orientation of olivine crystals suggest plastic flow ‘as the most likely mechanism for the genesis of anisotropy in the upper mantle. Since the direction of maximum velocity correlates in the ocean and on the continent with a number of tectonic features, a causal connection between anisotropy and dynamical processes related to plate motions must be suspected.

Deterministic Multi-Item Inventory Systems with Limited Capacity

Abstract: Available storage space frequently limits the aggregate stock level carried in multi-item inventory systems. In the deterministic case, the economic impact of storage capacity constraints may be reduced, and the utilization of the available facilities increased, by replenishment policies which include delivery schedules designed to avoid unnecessary clustering of order arrivals in the course of time. Under the assumption of a pure cycle reordering mode, simple expressions are derived for minimum storage space requirements and the associated optimal delivery schedules.

Floating-Point Computation of Functions with Maximum Accuracy

Abstract: Algorithms are given that compute multiple sums and products and arbitrary roots of floating-point numbers with maximum accuracy, The summation algorithm can be applied to compute scalar products, matrix products, etc. For all these functions, simple error formulas and the smallest floating-point intervals containing the exact result can be obtained.

Magnetic Relaxation by Quadrupolar Interaction of Ionic Nuclei in Non-Aqueous Electrolyte Solutions. Part I. Limiting Values for Infinite Dilution

Abstract: A brief outline of the electrostatic relaxation theory is given which, as compared to the previous stage, contains some minor improvements. Experimental results for the magnetic relaxation rates of the nuclei 7Li, 23Na, 87Rb. 133Cs. 35Cl. 81Br. and 127I in the correspondent alkali metal and halide ions are reported, which are dissolved in the solvents methanol, ethanol. formic acid, formamide. N-methylformamide, dimethylformamide, acetone, acetonitrile and dimethylsulfoxide. The data are given as a function of the salt concentration and the extrapolation values to infinite dilution are compared with predictions from several relaxation models. The pecularity of these relaxation models is given by the nature of the solvation shell which in turn is determined by the ionic radius and the structure of the solvent. Results are also compared with thermodynamic solvation data. Es wird zunachst ein kurzer Abris der elektrostatischen Relaxationstheorie gegeben, die gegenuber dem bisherigen Stande einige kleine Erweiterungen aufweist. Dann werden experimentelle Ergebnisse fur die Relaxationsraten der Kerne 7Li, 23Na, 87Rb, 133Cs, 35Cl, 81Br und 127I in den jeweiligen Alkalimetall- oder Halogenidionen mitgeteilt, die in den Losungsmitteln Methanol, Athanol, Ameisensaure, Formamid, N-Methylformamid, Dimethylformamid, Aceton, Acetonitril und Dimethylsulfoxid gelost sind. Die Daten sind als Funktion der Konzentration gegeben und die Extrapolationswerte auf unendliche Verdunnungen werden mit verschiedenen Relaxationsinodellen verglichen. Die Eigenart der Relaxationsinodelle ist durch die strukturellen Besonderheiten der Solvathulle gekennzeichnet, welche aus Ionenradius und Losungsmittelstruktur resultiert. Es werden auch Vergleiche init thermodynamischen Solvatationsgrosen gegeben.

Operator orderings and functional formulations of quantum and stochastic dynamics

Abstract: We study the connection between operator ordering schemes and thec-number formulations of quantum mechanics, which are based on generating functionals and functional integrals. We show by explicit construction that different operator ordering schemes are related to different functional and functional integral formulations of quantum mechanics. The results of these considerations are applied to classical non-linear stochastic dynamics by using the formal analogy between the Fokker-Planck equation and the Schrodinger equation.

EOL forms

Abstract: In this paper the notions of "L form" and its "interpretations" are introduced to define families of structurally similar L systems. The families of L systems thus defined are studied from a number of different points of view. It is felt that this novel approach will shed new light on many questions concerning L systems.

Über Eigenschaften und Anwendungsmöglichkeiten der erweiterten Intervallrechnung und des hyperbolischen Fastkörpers über ℝ

Abstract: Der Raum der Intervallrechnung | ℝ uber den reellen Zahlen ℝ ist der algebraischen Struktur nach eine additive, regulare, kommutative, isotone Halbgruppe, die sich stets in eine Gruppe einbetten last [4], [5]. Diese Einbettung wird in Kapitel 3 explizit angegeben. Dazu wird eine weitere Multiplikation eingefuhrt, die zusammen mit der Intervalladdition einen Fastkorper bildet. Diese sogenannte hyperbolische Multiplikation weist weitgehende Verwandtschaft mit dem Produkt der komplexen Zahlen auf, wie in einem ersten Uberblick gezeigt wird. Am Schlus werden einige Anwendungsmoglichkeiten dargestellt, die eine analytische Untersuchung von Problemen der Intervallrechnung unterstutzen.

Theoretical investigation of structure and stability of oligomers of LiH, NaH, LiF, and NaF

Abstract: The molecules LinHn, NanHn, LinFn, n=1,..., 4, and NaF and Na2F2 are investigated by means of extended basis set SCF and CEPA-PNO computations. In analogy to the D 2h structure of dimers, it is found that trimers have a planar cyclic D 3h equilibrium geometry. For the tetramer of LiH and NaH, the D 4h structure has about the same energy as the 3-dimensional T d structure, whereas the latter is definitely favoured for Li4F4. Correlation effects are investigated for the oligomerization of LiH and the dimerization of LiF. The effect of electron correlation on corresponding ΔE turns out to be small (<4 kJ/mol), except for the case that the T d tetramer is involved which has a rather large correlation energy.

[Patulin in foods of vegetable origin. 2. Several kinds of fruit and vegetables and fruit and vegetable products (author's transl)].

Abstract: Patulin was found in fruit with spontaneous brown rot (bananas, pineapples, grapes, peaches, apricots) as well as in moldy compots and in sallow-thorn juice. Fruit, vegetables and fruit and vegetable product were artificially infected with Penicillium expansum, P. urticae and Byssochlamys nivea; patulin was subsequently found in peaches, apricots, greengages, bananas, strawberries, honeydew melons, tomatoes, red and green paprika, cucumbers and carrots; in several kinds of compot, in tomato juice and tomato pulp --but not in ketchup. The influence of the temperature on growth and toxin production is different in the various fungal strains; in the temperature range of 5 degrees C to 25 degrees C, however, the possibility of patulin synthesis must nearly always be expected.

Heat transfer between an impinging jet and a continuously moving flat surface

Abstract: Experiments have been carried out to determine heat transfer rates from a continuously moving belt to an air jet impinging normally. The parameters that were varied included the jet velocity (4 < VN < 40 m/s), the jet width (4.8 < B < 19 mm), the nozzle-to-plate distance (3 < H/2B < 11) and the belt speed (0. 15 < VB < 5. 5 m/s). An infrared thermometer was used for the measurement of temperature of the moving belt. The average heat transfer coefficients increase with belt speed steeply initially to a maximum value and then remain almost constant for all higher belt speeds. The maximum heat transfer coefficients are about 1.5 to 2.0 times higher than those predicted for the stationary surface. The present data on continuously surface in still air and in impinging jet flow are well compared with the data on rotating cylinders reported in the literature.

Superconductors under dynamic mechanical stress

Abstract: Experiments were performed to study the cause for the training phenomenon in superconducting magnets. Stress-strain curves of commercial superconductors were taken with applied field and transport current. In experiments where the samples were strained in a constant field and with a transport current below I c , the normal transition occured at successively higher stress levels. That means, a training behaviour of short samples was found. In the low strain region a distinct microplastic behaviour of NbTi wires was found by monitoring acoustic emission. The irreversibility of the detected signals indicates that mechanisms of permanent deformation exist at strain levels well below the macroscopic elastic limit. These mechanisms may be responsible for the training effect.

Hill-acitivity and P700 concentration of chloroplasts isolated from radish seedlings treated with-indoleacetic acid, kinetin of gibberellic acid.

Abstract: The Hill-activity (reduction of DCPIP or methylviolgen) and the concentration of P700 were studied in chloroplasts isolated from cotyledons of radish seedlings (Raphanus sativus L. saxa Treib), which had been grown with the addition of beta-indoleacetic acid (IAA), kinetin, or gibberellic acid. 1) The photosynthetic activity of young chloroplasts from 3 day old Raphanus seedlings is very high (c. 180 micron mol O2/mol chlorophyll X h) and decreases continuously thereafter with increasing age. The steady state Hill-activity is reached after 8 to 10 days (values of 55 to 50 micron mol O2/mg chlorophyll X h). 2) Chloroplasts from plants treated with IAA or kinetin not only exhibit higher plastoquinone levels 1,2, but also a higher P700-content and a higher Hill-activity. The promotion effect is more pronounced with kinetin (+36 tb 40%) than with IAA (+12 to 17%). 3) Gibberellic acid has a different effect on composition and activity of chloroplasts. In younger seedlings the Hill-activity appears to be somewhat stimulated, without promotion effect on plastoquinone 2 or P700 concentration. After 10 days GA3-treated plants show signs of chlorosis combined with a strong decrease in photosynthetic activity. 4) The data clearly demonstrate that the composition and activity of the photosynthetic apparatus are under phytohormone control. IAA and even better kinetin promote the light induced formation of pigment systems and electrontransport chains. GA3 seems to block the rebuilding of the photosynthetic apparatus under steady state conditions.

Model Orientation Dependent Pair Distribution Functions in Three Dimensions for the Liquid Mixtures of Propionic Acid and of Ethanol with Carbon Tetrachloride

Abstract: Proton magnetic relaxation rates of the methyl, the methylene and the OH group of propionic acid and of ethanol in the mixture with CCl4 have been measured. These compounds were partly labled by deuterons and the corresponding deuteron magnetic relaxation rates were also measured. From all these data the proton intra- and intermolecular relaxation rates were determined together with proton relaxation rates caused by another proton containing group. The latter results then yielded intermolecular closest distances of approach between the various groups and from these orientation dependent model pair distribution functions in three dimensions have been constructed. It has been shown that the propionic acid pair configurations in CCl4 resemble somewhat to those found in the solvent water whereas for ethanol the behaviour in the two solvents is markedly different. Protonenmagnetische Relaxationszeiten der Methyl-, der Methylen- und der OH-Gruppe von Propionsaure und von Athanol in ihren Mischungen mit CCl4 wurden gemessen. Die Verbindungen waren teilweise deuteriert und die entsprechenden Deuteronen-Relaxationszeiten wurden gleichfalls gemessen. Aus all diesen Daten wurden dann die intra- und intermolekularen Protonen-Relaxationsraten zusammen mit denjenigen intermolekularen Relaxationsraten, die durch nicht-aquivalente Protonen bewirkt wurden, gewonnen. Die letzteren Ergebnisse lieferten intermolekulare dichteste Annaherungsabstande zwischen den verschiedenen Gruppen, aus diesen wurden orientierungsabhangige Modell-Paarverteilungsfunktionen in drei Dimensionen konstruiert. Es konnte gezeigt werden, das die Propionsaure- Paarkonfigurationen in CCI4 nicht sehr verschieden von denen sind, die auch im Losungsmittel Wasser gefunden wurden. Im Gegensatz dazu ist das Verhalten von Athanol in den beiden Losungsmitteln deutlich verschieden.