Showing papers by "Delft University of Technology published in 1973"
TL;DR: In this paper, the kinetics of the methanation of CO2 in H2 on a supported nickel catalyst have been measured at partial pressures of CO 2 below 0.02 atm and at atmospheric pressure and at temperatures between 200 and 230 °C.
176 citations
TL;DR: In this paper, a rigorous solution was obtained for the problem of radiation from an electric point charge that moves, at a constant speed, parallel to an electrically perfectly conducting grating.
Abstract: A rigorous solution is obtained for the problem of radiation from an electric point charge that moves, at a constant speed, parallel to an electrically perfectly conducting grating. The relevant vectorial electromagnetic problem is reduced to two two-dimensional scalar ones. A Green’s-function formulation of the two problems is employed. For both cases, an integral equation of the second kind for the remaining unknown function is derived. This integral equation is solved numerically by a method of moments. Some numerical results for the radiation from a moving point charge above a sinusoidal grating are presented; in particular, the power losses of the point charge have been estimated.
131 citations
TL;DR: In this paper, experiments have been made in the turbulent flow through a conduit of rectangular cross-section with large aspect ratio and one of the long walls has been made rough, except for a strip, located centrally.
Abstract: In continuation to an earlier publication, experiments have been made in the turbulent flow through a conduit of rectangular cross-section with large aspect ratio. One of the long walls has been made rough, except for a strip, located centrally. As shown in the earlier paper, secondary currents will occur in the regions of transition from smooth to rough wall-condition. The main purpose of the investigation was to check the admissibility of the simplifying assumptions made to the mechanical-energy balance equation. The results of the measurements indeed justified the neglect of unimportant terms of this equation, leading to the following rule. When in a localized region the production is much greater (smaller) than the viscous dissipation, there must be a secondary current that transports turbulence-poor fluid into (outwards) this region and turbulence-rich fluid outwards (into) the region.
97 citations
TL;DR: In this paper, a theory of the aeration produced by the impact of a high speed water jet on a water surface is given, and the boundary conditions for the theory have a physical meaning.
93 citations
TL;DR: In this paper, an approximate method is presented which produces a handling diagram useful for the study of steady-state turning behavior at different values of steer angle, path radius and speed.
Abstract: SUMMARY An approximate method is presented which produces a handling diagram useful for the study of steady-state turning behaviour at different values of steer angle, path radius and speed In three successive parts the steady state response of simple and more elaborate vehicle models and the stability of the resulting motion are discussed.
67 citations
TL;DR: In this paper, a simplified analysis of the turning behavior of motor vehicles is presented, based on a simplified version of the Part 3: More Elaborate Systems (ELS) model.
Abstract: (1973). Simplified Analysis of Steady-State Turning Behaviour of Motor Vehicles Part 3: More Elaborate Systems. Vehicle System Dynamics: Vol. 2, No. 4, pp. 185-204.
65 citations
TL;DR: In this article, the diffraction pattern due to a plane H-polarized electromagnetic wave is investigated, when this wave is incident upon an infinitely long slit of finite width in an opaque screen of non-vanishing thickness.
Abstract: The diffraction pattern due to a plane H-polarized electromagnetic wave is investigated, when this wave is incident upon an infinitely long slit of finite width in an opaque screen of non-vanishing thickness. The screen is located between the plane boundaries of two media with different electromagnetic properties. A Green's function formulation of the problem is employed, leading to a system of four coupled integral equations in which the field distributions in the slit occur as unknowns. Numerical results are presented for the field just below the screen as well as for the far field pattern.
55 citations
01 Sep 1973
TL;DR: In this article, the propagation of electromagnetic surface waves along a radially inhomogeneous dielectric waveguide is investigated in terms of differential equations to be satisfied by the radially dependent parts of the electromagnetic field vectors.
Abstract: The propagation of electromagnetic surface waves along a radially inhomogeneous dielectric waveguide is investigated. The problem is formulated in terms of differential equations to be satisfied by the radially dependent parts of the electromagnetic field vectors. The dielectric waveguide is assumed to consist of a homogeneous cladding of infinite extent and a radially inhomogeneous core of higher permittivity. Numerical solutions of the differential equations in the core are obtained by two different methods, viz. by direct numerical integration and by substitution of an appropriate power series expansion. In the cladding the field is expressed in terms of modified Bessel functions. Imposing the boundary conditions at the interface of core and cladding, an equation for the unknown propagation coefficient is obtained. From this equation the propagation coefficients for the lower order modes are computed numerically. Numerical results are presented for some permittivity profiles of practical interest in single-mode transmission along optical fibres.
50 citations
TL;DR: In this paper, the authors analyzed the effect of imperfection sensitivity of thin-walled compression members to initial waviness of the composing walls and to imperfection of the column axis.
46 citations
TL;DR: In this paper, a polynomial-based method for the analysis of the adsorption potential distribution function is proposed, which is based on the idea that ǫ(U ) may be represented by an exponential higher degree polynomial, thus allowing for skew distributions and distributions with more extremes.
46 citations
TL;DR: In this paper, a simplified analysis of the stability of the turning behavior of a vehicle is presented, based on a simple simplified version of the Steady State Turn Behavior of Vehicles.
Abstract: (1973). Simplified Analysis of Steady-State Turning Behaviour of Motor Vehicles Part 2: Stability of the Steady-State Turn∗. Vehicle System Dynamics: Vol. 2, No. 4, pp. 173-183.
TL;DR: In this paper, a new model for the prediction of the wall shear stress as a function of velocity and acceleration changes is introduced for one-dimensional flow analysis under nonsteady conditions.
Abstract: Measured data of velocity changes in oscillatory flows (0.16Hz-0.36Hz) are presented. The actual wall shear stresses obtained from the measurements are compared to calculated values based on steady flow relations and Zielke's model. A new model for the prediction of the wall shear stress as function of velocity and acceleration changes is introduced. The proposed model may be a suitable basis for the prediction of friction data for one-dimensional flow analysis under nonsteady conditions.
TL;DR: In this article, a new structure was proposed for the toxic antibiotic bongkrekic acid (BA), which is given by the formula: 3-carboxymethyl-17-methoxy-6,18,21-trimethyldocosa-2,4,8,12,14, 18,20-heptaenedioic acid.
TL;DR: Step-wise cystometry has been developed to analyze the pressure-relaxation phenomena of the bladder in mongrel dogs and shows that a mathematical model consisting of two exponentials and a constant can befitted to the measurements.
01 Jan 1973
TL;DR: In this article, a series of alkyl- and dialkylnaphthalenes over palladium on carbon in acetic acid have been studied at 80 °C and atmospheric pressure.
TL;DR: In cases where the usual criteria used in identification seem to be inadequate, the simple hydrocarbon assimilation test may be useful, because some perfect genera like Hansenula, Kluyveromyces andSaccharomyces lack hydrocarbon-assimilating representatives.
Abstract: A large number of yeasts were screened for the ability to assimilate hydrocarbons. Not only representatives of the genusCandida, but also species from other perfect and imperfect genera are able to usen-alkanes as sole carbon and energy source. The significance of this feature in yeast systematics is discussed. In general, all strains of a species share either the ability to assimilate hydrocarbons or the failure to do so. Exceptions are found in species regarded as heterogeneous, likeCandida sake, Candida diddensii andCandida zeylanoides. In cases where the usual criteria used in identification seem to be inadequate, the simple hydrocarbon assimilation test may be useful. Also in subgrouping the generaCandida andTorulopsis the test may be of value, because some perfect genera likeHansenula, Kluyveromyces andSaccharomyces lack hydrocarbon-assimilating representatives.
TL;DR: In this paper, a comparison of results obtained with various boundary conditions at the wall of the channels was made, by comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation was found for various points along the blood channel.
TL;DR: In this article, an improved approximation of the theory of the dynamic frequency response of side force and aligning torque acting upon the rolling wheel when the latter is moved laterally and swivelled about the vertical axis, is presented.
Abstract: An improved approximation of the theory of the dynamic frequency response of side force and aligning torque acting upon the rolling wheel when the latter is moved laterally and swivelled about the vertical axis, is presented. The method is particularly suitable for application in vibration problems of steering and suspension systems of automobiles and aircraft where relatively high speed and high frequency phenomena play a role. The theoretical results show satisfactory agreement with experimental data. Calculations indicate that the inertia of the tire decreases the tendency to shimmy at higher frequencies and speeds of travel. For castered wheels however, tire inertia may have an adverse effect due to its unfavorable influence upon the side force response to swivel motions.
TL;DR: In this article, it was shown that it is not possible to relate the surface properties of primitive ionic crystal surfaces directly to the latent heat, and the authors proposed a statistical method to calculate the properties of Kossel crystal-fluid interfaces.
TL;DR: It is shown that small humic ions with a mean, equivalent weight of 70–80 gram per equivalent and a mean apparent equivalent volume can be sorbed by the tested membranes in a stoichiometric ion exchange process.
TL;DR: When treated with alkali metals in liquid ammonia at −70° cycloheptatriene adopts two electrons and a proton yielding the cyclohexadienyl anion as mentioned in this paper.
Abstract: When treated with alkali metals in liquid ammonia at −70° cycloheptatriene adopts two electrons and a proton yielding the cycloheptadienyl anion. Protonation of this anion yields 1,3- and 1,4-cycloheptadiene in a ratio which depends rather strongly on the proton donor used. Decreasing acid strength of the proton donor favours 1,3-cycloheptadiene formation. The selectivity of protonation also depends on the alkali metal used and on the concentration. At −33° ammonia protonates the cycloheptadienyl anion yielding 1,3-cycloheptadiene. This enables one step reduction of cycloheptatriene to cycloheptene. Reduction of 7-deuterocycloheptatriene shows the first proton addition to cycloheptatriene to be irreversible.
Alkylation of the cycloheptadienyl anion yields mixtures of 3-alkyl-1,4-cycloheptadiene and 5-alkyl-1,3-cycloheptadiene in which the former compound invariably predominates.
TL;DR: In this paper, a new approach for the numerical integration of the Navier-Stokes equations is presented, which is based on the perturbation of the Poisson type equation.
Abstract: A new approach for the numerical integration of the Navier-Stokes equations is presented. It is based on the perturbation of the Poisson type equation. The system of nonlinear partial differential equations obtained is solved by means of an explicit operator. Some results are presented for the problem of steady flow in a square cavity. They are in good agreement with the calculations made by Greenspan, Fortin, Teman and Peyret, Bourcier and FranCois and Burgraff. Reynolds numbers up to 400 have been considered.
01 Sep 1973
TL;DR: In this paper, experiments were carried out with Ni samples containing different amounts of carbon and the temperature range used is 800 to 1295°, where a two-phase character is formed, for a high carbon content at all temperatures and for a low carbon content (0.06 wt pct) below 1200°.
Abstract: Experiments are carried out with Ni samples containing different amounts of carbon. The temperature range used is 800 to 1295°. In the beginning of the diffusion process a layer with a two-phase character is formed, for a high carbon content(i.e., 0.4 wt pct) at all temperatures and for a low carbon content (0.06 wt pct) below 1200°. The layer consists of the phases Mo2C and an Ŋ-carbide Mo54Ni30C18. Above 1000° this Ŋ-carbide is present also as a single-phase layer adjacent to this two-phase layer. After an incubation time a layer consisting of another Ŋ-carbide Mo6M6C is formed in the couples; this has a homogeneity range of only 0.5 at. pct Ni. There exists an intricate relationship between the two-phase layer and the layers of the pure Ŋ-carbides. After a very long annealing time at 1200°, σ-MoNi appears as a part of the Mo6Ni6C layer.
TL;DR: In this paper, the authors investigated the scattering of a plane electromagnetic wave by a perfectly conducting elliptic cylinder, based upon the expansion of the scattered wave functions in terms of Mathieu functions.
Abstract: The scattering of a plane electromagnetic wave by a perfectly conducting elliptic cylinder is investigated theoretically. The calculations are based upon the expansion of the scattered wave functions in terms of Mathieu functions. Both E- and H-polarized waves are considered. Numerical results, in particular for the scattering cross-section, are presented for cylinders the cross-sectional dimensions of which are up to many wavelengths (e.g. distance between the focal lines up to 20 wavelengths).
01 Oct 1973
TL;DR: In this paper, the authors used the angle of repose to determine the minimum fluidization velocity in a homogeneously fluidized bed, which is a simple and easily interpretable value of Umf.
TL;DR: In this paper, a viscometer is described in which the capillary wall temperature is controlled by an adjustable low voltage current directly flowing through the thin tube wall, where the current can be adjusted by a voltage controller.
Abstract: A viscometer is described in which the capillary wall temperature is controlled by an adjustable low voltage current directly flowing through the thin tube wall