Showing papers by "Karlsruhe Institute of Technology published in 1984"
TL;DR: In this article, measurements of the flow generated by a jet issuing from a circular outlet in a wall into a cross-stream along this wall were performed with a three-sensor hot-wire probe.
Abstract: The paper reports on measurements in the flow generated by a jet issuing from a circular outlet in a wall into a cross-stream along this wall. For the jet-to-crossflow velocity ratios R of 0.5, 1 and 2, the mean and fluctuating velocity components were measured with a three-sensor hot-wire probe. The hot-wire signals were evaluated to yield the three mean-velocity components, the turbulent kinetic energy, the three turbulent shear stresses and, in the case of R = 0.5, the terms in the turbulent-kinetic-energy equation. The results give a quantitative picture of the complex three-dimensional mean flow and turbulence field, and the various phenomena as well as their dependence on the velocity ratio R are discussed in detail.
567 citations
TL;DR: In this article, two approaches are proposed to predict particle trajectories in the fluid phase as a result of forces acting on particles, which are referred to as the Lagrangian approach and the Eulerian approach.
287 citations
TL;DR: In this article, a more refined model is introduced, in which algebraic expressions are derived for the Reynolds stresses in the momentum equations for the secondary motion by simplifying the modelled Reynolds-stress equations of Launder, Reece & Rodi.
Abstract: Experiments on and calculation methods for flow in straight non-circular ducts involving turbulence-driven secondary motion are reviewed. The origin of the secondary motion and the shortcomings of existing calculation methods are discussed. A more refined model is introduced, in which algebraic expressions are derived for the Reynolds stresses in the momentum equations for the secondary motion by simplifying the modelled Reynolds-stress equations of Launder, Reece & Rodi (1975), while a simple eddy-viscosity model is used for the shear stresses in the axial momentum equation. The kinetic energy k and the dissipation rate e of the turbulent motion which appear in the algebraic and the eddy-viscosity expressions are determined from transport equations. The resulting set of equations is solved with a forward-marching numerical procedure for three-dimensional shear layers. The model, as well as a version proposed by Naot & Rodi (1982), is tested by application to developing flow in a square duct and to developed flow in a partially roughened rectangular duct investigated experimentally by Hinze (1973). In both cases, the main features of the mean-flow and the turbulence quantities are simulated realistically by both models, but the present model underpredicts the secondary velocity while the Naot-Rodi model tends to overpredict it.
277 citations
TL;DR: In this paper, a quantum-mechanical model for the phase difference across a superconducting tunnel junction is proposed, where the quasiparticle degrees of freedom are responsible for dissipation and noise in the system.
Abstract: Basing our model and method on the microscopic theory we formulate a quantum-mechanical description for the relevant variable in a superconducting tunnel junction, i.e., the phase difference across the junction. The quasiparticle degrees of freedom are responsible for dissipation and noise in the system. Because of the discreteness of the charge-transfer process, the noise is shot noise. The energy gaps in the superconductors lead to further interesting features. We discuss the consequences of these physical effects on macroscopic quantum phenomena.
231 citations
TL;DR: In this article, an analytical study is made to calculate the axial velocity and pressure distributions in both the intake and exhaust conduits of plate heat exchangers, the flow distribution in the channels between the plates and the total pressure drop.
218 citations
TL;DR: In this paper, a reaction catalytique test is used for obtenir des donnees sur the structure of zeolites inconnues in the presence of palladium sous forme palladium.
209 citations
TL;DR: In the supernatant of UV-treated cells, a heat-labile ammonium sulfate precipitable factor of more than 10 kd was detected which, upon transfer to nonirradiated cells, mimicked UV in the UV-induced synthesis of gene products.
147 citations
TL;DR: In this paper, a simple equivalent circuit characterizing the barrier-and porous-layer was proposed to characterize the dielectric constant and specific resistivity of the barrier and porous layers.
147 citations
TL;DR: In this paper, the actual contact time of the material at the hot surface is known, and the mixing number Nmix is necessary in order to predict drying rates for bench scale as well as for industrial dryers.
Abstract: In vacuum contact drying of particulate material heat is supplied from a hot surface to adjacent layers of mechanically agitated material. The drying rate curves can be predicted from physical properties alone provided that the actual contact time of the material at the hot surface is known. For mechanically agitated particulate material the actual contact time has been correlated to the time scale of the agitator by the “penetration model”. Only one empirical parameter, the so called mixing number Nmix is necessary in order to predict drying rates for bench scale as well as for industrial dryers.
117 citations
Proceedings Article•
06 Aug 1984TL;DR: This work demonstrates the advantage of using a many-sorted resolution calculus by a mechanical solution of a challenge problem, known as "Schubert's Steamroller", which had been unsolved by automated theorem provers until now.
Abstract: We demonstrate the advantage of using a many-sorted resolution calculus by a mechanical solution of a challenge problem. This problem known as "Schubert's Steamroller" had been unsolved by automated theorem provers until now. Our solution clearly demonstrates the power of a many-sorted resolution calculus. The proposed method is applicable to all resolution-based inference systems.
113 citations
TL;DR: In this article, the mean adsorption isotherms of MCC and a potato starch and the precision data, viz. the repeatability/reproducibility of the total sorption measurement procedures, were determined.
TL;DR: In this article, the mixing number was found to lie between 2 and 25, depending on the design of the stirrer, which is a parameter introduced to describe the random particle motion.
Abstract: The heat transfer between packed and stirred beds and immersed surfaces is controlled by the contact resistance at the surface followed by the heat penetration resistance of the bulk. Both resistances can be predicted from model equations with sufficient accuracy. The contact resistance and the bulk penetration resistance for packed beds follow from physical properties, while the prediction of the bulk penetration resistance for stirred beds requires the introduction of an empirical parameter, the so-called mixing number in order to describe the random particle motion. The mixing number was found to lie between 2 and 25, depending on the design of the stirrer.
TL;DR: In this article, the mechanisms of heat transfer between the surfaces of heat exchanger elements and gas-solid fluidized beds are discussed in detail, and a theoretical model, presented some years ago, is slightly modified and further developed to improve its applicability within a wide range of variables.
Abstract: After some general remarks about fluidization, and a section on the hydrodynamic behaviour of fluidized beds, the mechanisms of heat transfer between the surfaces of heat exchanger elements and gas—solid fluidized beds are discussed in detail. A theoretical model, presented some years ago, is slightly modified and further developed to improve its applicability within a wide range of variables. The model makes use of some of the basic concepts of molecular kinetic theory as applied to solid particles in a fluidized bed. A complete derivation as well as all the parameters required to apply the model equations are given.
TL;DR: In this article, double deprotonation of (R)-2-acetoxy-1,1,2-triphenylethanol was used to add stereoselective properties to aldehydes.
TL;DR: In this paper, the intermolecular pair potentials used in these calculations were derived with a new model which was introduced recently, and calculated data on thermodynamics, static structure, self-diffusion coefficient and reorientational correlation times are compared with experimental and other molecular dynamics results.
Abstract: Results of molecular dynamics simulations are reported for CH3F, CHF3, CH3Cl, CH3CN, CO2 and CS2. The intermolecular pair potentials used in these calculations were derived with a new model which was introduced recently. The calculated data on thermodynamics, static structure, self-diffusion coefficient and reorientational correlation times are compared with experimental and other molecular dynamics results.
TL;DR: In this article, a model based on bulk diffusion towards a partially active electrode surface was proposed to characterize the dc and ac polarization behavior of the Ag/Ag+ system theoretically and experimentally, and it was demonstrated that surface relaxation may give rise to an inductive part in the ac-impedance diagram.
TL;DR: In this article, a weakly nonlinear convective instability theory is presented which explains this behaviour, and isolates this "purely thermal" mechanism of pattern selection, showing that the interfacial corrugations that result are two-dimensional when this solid is thin but hexagonal when the solid is thick.
Abstract: A horizontal layer is heated from below and cooled from above so that the enclosed single-component liquid is frozen in the upper part of the layer. When the imposed temperature difference is such that the Rayleigh number across the liquid is supercritical, there is Benard convection coupled with the dynamics of the solidification interface. An experiment is presented which shows that the interfacial corrugations that result are two-dimensional when this solid is thin but hexagonal when the solid is thick. A weakly nonlinear convective instability theory is presented which explains this behaviour, and isolates this ‘purely thermal’ mechanism of pattern selection. Jump behaviour is seen in the liquid-layer thickness at the onset of hexagonal convection.
TL;DR: In this paper, the yields of the light fission products from the thermal-neutron-induced fission of 239 Pu were measured as a function of A, Z, the kinetic energy E and the ionic charge states q.
TL;DR: In this article, a methode des differences finies de jets libres fortement tourbillonnaires is defined, and a recirculation apparait a proximite de la tuyere, in which l'introduction de modifications liees au tour-billonnement dans le modele de turbulence k-e and aux changements dans les conditions aux limites pour la vitesse de dissipation e and la Vitesse radiale au plan d'entree du jet
Abstract: Calcul par la methode des differences finies de jets libres fortement tourbillonnaires. Une recirculation apparait a proximite de la tuyere. Etude de la reponse du champ calcule a l'introduction de modifications liees au tourbillonnement dans le modele de turbulence k-e et aux changements dans les conditions aux limites pour la vitesse de dissipation e et la vitesse radiale au plan d'entree du jet
TL;DR: In this paper, a theoretical description of the transport processes allows the optimization of the coating parameters according to the boundary conditions, and an electrode arrangement which meets electrical and inflow technique requirements is proposed to achieve a deposition efficiency of more than 80%.
TL;DR: Three distinct definitions of rectilinear convex hulls for point sets in general are examined, some of their consequences are pointed out, and optimal algorithms to compute the corresponding rectilInear conveX hulls of a finite set of points in the plane are given.
TL;DR: The Lorenz curve of income after tax is known to dominate the one before tax for all given income distributions if and only if average tax liability is monotone increasing with income as discussed by the authors.
TL;DR: In this article, the influence of wall proximity on hot-wire readings was eliminated by using a highly insulating wall material and using a single hotwire boundary layer probe to obtain the longitudinal velocity informatemperature-wake sensor for the cross flow flow information.
Abstract: Hot-wire anemometer measurements, using two types of probes, are reported for wall boundary layer flows with particular attention being given to the near-wall region and to measurements at high Reynolds numbers up to Rϕ≈ 15,000. To obtain accurate near-wall measurements, the influence of wall proximity on hot-wire readings was eliminated by using a highly insulating wall material. Measurements were carried out with a single hot-wire boundary layer probe to obtain the longitudinal velocity informatemperature-wake sensor for the cross flow tion and a hot-wire, information.
TL;DR: In this paper, thin films of doped In2O3 and SnO2 were prepared by the "corona spray pyrolysis" technique with a deposition efficiency of 80%.
TL;DR: In this article, the effects of underpotential lead and bismuth adsorbates on the cathodic reduction of O2 and H2O2 in perchloric acid solution obtained on rotating disc Au and Ag single crystal surfaces of (111), (100) and (110) crystallographic orientation are discussed.
TL;DR: In this paper, a model of liquid acetonitrile has been analyzed for correlation functions appropriate to infrared, Raman and N.M.R. measurements, and very good agreement with experiment is found.
Abstract: Molecular dynamics calculations have been carried out for a model of liquid acetonitrile. Results are reported for correlation functions appropriate to infrared, Raman and N.M.R. measurements, and very good agreement with experiment is found. Both the tumbling and the spinning motion of the molecule have been studied and the results are used to discuss the choice of nuclear quadrupole coupling constant in the analysis of T 1 measurements, the interpretation of N.M.R. data in terms of diffusion coefficients, vibrational relaxation and Coriolis coupling for the perpendicular Raman bands, and the validity of the J diffusion model. The tumbling motion is similar to the motion seen in many organic liquids, with evidence of a cage effect. The spinning motion is also hindered, but the reorientation is faster and there is no apparent cage effect. The characteristic, non-lorentzian lineshape of the perpendicular infrared and Raman bands of CH3X molecules is recovered; the associated correlation times show a signif...
TL;DR: In this paper, the breaking of N = 2 extended supersymmetry to N = 1 was examined and Lagrangians and transformation laws for the generalized N =2 Akulov-Volkov goldstino field were derived.
Journal Article•