Showing papers by "Eindhoven University of Technology published in 1976"
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TL;DR: A survey is given of the recent literature on 1/ f noise and proposed models for mathematical models, empirical relations and physical models are discussed.
Abstract: A survey is given of the recent literature on 1/ f noise. Proposals for mathematical models, for empirical relations and for physical models are discussed. The present situation is evaluated and some unsolved problems are indicated.
359 citations
TL;DR: In this article, the composition of cathode mass loss was analyzed for cadmium, copper and molybdenum vacuum arcs and it was shown that two dominant flows are present, one consisting of ions, the other of molten droplets which have sizes in the order of microns to tens of microrons.
Abstract: The composition of cathode mass loss was analysed for cadmium, copper and molybdenum vacuum arcs. It showed that two dominant flows are present, one consisting of ions, the other of molten droplets which have sizes in the order of microns to tens of microns. The droplet flow is mainly oriented along the cathode plane and is strongly dependent on the fusion temperature of the cathode metal and the charge transfer by the arc. The cathode mass loss in vapour form is considered to be small.
337 citations
TL;DR: In this article, Gauthier-Villars implique l'accord avec les conditions générales d'utilisation (http://www.numdam.org/legal.php).
Abstract: © Gauthier-Villars (Éditions scientifiques et médicales Elsevier), 1976, tous droits réservés. L’accès aux archives de la revue « Annales scientifiques de l’É.N.S. » (http://www. elsevier.com/locate/ansens) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/legal.php). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.
234 citations
TL;DR: In this article, the authors considered the flow streaming into a porous and permeable medium with arbitrary but smooth wall surface and considered the Euler equation (in the pure fluid region) and generalized Darcy's law in which the convective acceleration is taken into account.
Abstract: The flow streaming into a porous and permeable medium with arbitrary but smooth wall surface is considered on the basis of the Euler equation (in the pure fluid region) and a generalized Darcy's law in which the convective acceleration is taken into account. The asymptotic behavior of the flow for small permeability of the medium is investigated. It is shown that the flow in the porous medium is irrotational except in the boundary layer next to the surface. The velocity distribution in the boundary layer is given in a universal form. Proper boundary conditions connecting the potential flow in the pure fluid region and the potential flow in the porous medium are obtained when the boundary layer is neglected.
117 citations
TL;DR: In this paper, the anomalous behavior of the Seebeck coefficient below the Verwey temperature was interpreted with a model of mixed conduction, and the temperature range 80-300 K on five synthetic single crystals of magnetite, differing in oxygen stoichiometry.
Abstract: Thermolectric-power measurements were carried out in the temperature range 80-300 K on five synthetic single crystals of magnetite, ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$, differing in oxygen stoichiometry. The anomalous behavior of the Seebeck coefficient below the Verwey temperature was interpreted with a model of mixed conduction.
97 citations
TL;DR: In this article, the thiophene hydrodesulfurization activity was measured under continuous flow conditions at 400 °C and atmospheric pressure for Mo- and Co-containing catalysts supported on different materials (γ- and η-Al 2 O 3 and SiO 2 ) and using different methods of preparation.
90 citations
TL;DR: In this article, the sulfur uptake of commercial and laboratory prepared catalysts of the type MoO 3 γ-Al 2 O 3, CoO MoO 2 O O 3 and CoO CoO O 3 O 3 was studied at 400 °C using H 2 /SH 2 and thiophene/H 2 as sulfiding gases.
74 citations
TL;DR: In this paper, a surface roughening of glass capillary columns has been studied and a method of surface crystallization based on controlled devitrification has been developed, which results in a surface comparable with an HCl-etched surface.
62 citations
TL;DR: In this article, a high-precision gas chromatographic system, in combination with high-resolution stainless-steel capillary columns and three stationary phases of different polarity, was used to study the separation and retention behaviour of 47 alkyl-benzenes up to C15, including all possible isomers between C6 and C10.
58 citations
TL;DR: In this article, a potential scan is applied from /t-1.0 V to 2.6 V and α-PbO2 is formed underneath the PbSO4 film.
TL;DR: In this paper, a more precise version of the basic canonical theorem, some considerations on conservation laws and their relation, a complete treatment of the stability of the models, especially with respect to the wave amplitude, a short treatment of Lagrangian theory, a stable discrete model which might be useful for numerical experiments and an extension of the method to the case of slowly varying water depth.
Abstract: In this paper, a sequel to two others [1, 2], some extensions and improvements of this earlier work are presented. Among these are: A more precise version of the proof of the basic canonical theorem, some considerations on conservation laws and their relation, a more complete treatment of the stability of the models, especially with respect to the wave amplitude, a short treatment of the Lagrangian version of the theory, a stable discrete model which might be useful for numerical experiments and an extension of the method to the case of slowly varying water depth.
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01 Jan 1976TL;DR: The classical Viterbi decoder recursively finds the trellis path (code word) closest to the received data, and the syndrome decoder first forms a syndrome, which determines the noise sequence of minimum Hamming weight that can be a possible cause of this syndrome.
Abstract: The classical Viterbi decoder recursively finds the trellis path (code word) closest to the received data. Given the received data, the syndrome decoder first forms a syndrome instead. Having found the syndrome, that only depends on the channel noise, a recursive algorithm like Viterbi's determines the noise sequence of minimum Hamming weight that can he a possible cause of this syndrome. Given the estimate of the noise sequence, one derives an estimate of the original data sequence. The bit error probability of the syndrome decoder is no different from that of the classical Viterbi decoder. However, for short constraint length codes the syndrome decoder can be implemented using a read-only memory (ROM), thus obtaining a considerable saving in hardware. The syndrome decoder has at most \frac{3}{4} as many path registers as does the Viterbi decoder. There exist convolutional codes for which the number of path registers can be even further reduced.
TL;DR: In this article, a method for the determination of hydroperoxides in reaction mixtures from the oxidation of hydrocarbons is described, which is carried out by adsorption chromatography.
TL;DR: In this article, the effects of changing temperatures on the 13C n.m.r. chemical shifts of a number of 1,l-disub-stituted ethylenes are presented.
Abstract: C n.m.r. chemical shifts of a number of 1,l-disub- stituted ethylenes are presented. Moreover, effects of changing temperatures on the 13C n.m.r. chemical shifts of some of these compounds as well as of three normal alkanes are given. These variations in chemical shifts are attributed to varying amounts of sterically induced shifts in the different conformational equilibria. In addition to the well-known 1,4 interaction between two alkyl groups shielding effects on the carbon atoms of the connecting bonds are also proposed. No definite explanation of this effect is presented at this time. It is further shown that no simple correlations exist between 13C n.m.r. chemical shifts and calculated total charge den- sities at this level. Instead, the experimental results in 1-alkenes are rationalized by assuming a linear dependence of the 13C n.m.r. chemical shifts of C-1 and C-2 via rehybridizations on changes in bond angles for small skeletal deformations caused by steric in- teractions. These changes in geometries, as well as conformational energies in three 1-alkenes, were calculated by means of VFF cal- culations. Finally, upfield shifts for both C-2 and C-4 are proposed for those conformations of 1-alkenes in which the C-3-C-4 group interacts with the p,-orbital of C-2.
TL;DR: In this paper, four models of constriction dominated contacts are considered, each with one circular contact area, and the results of different methods of calculating the 1/f noise intensity of contacts are presented.
Abstract: Results of different methods of calculating the 1/f noise intensity of contacts are presented. Four models of constriction dominated contacts are considered each with one circular contact area. In two models the equipotential surfaces are oblate ellipsoids, the first model having an insulating hyperboloid boundary and the second an insulating plane boundary, with a contacting spot. The other two models have spherical zone equipotentials, one having a conic boundary, the other an insulating plane with a conducting spot. The last-mentioned model was calculated earlier by Hooge who used an approximation which we shall call the adding sheel approach. Our results of the calculation methods for the various models are compared with his simple results.
TL;DR: The direct coupling of a capillary column (WCOT) to a mass spectrometer produced spectra of the main PCB components, many of which could be used in the identification of isomeric PCBs.
TL;DR: In this article, the effect of a counter flow of electrolyte on the profile of the zone boundary has been studied, and a new type of membrane pump is described for experiments with a regulated counter flow.
TL;DR: A submitted manuscript is the version of the article upon submission and before peer-review as discussed by the authors, while a published version is the final layout of the paper including the volume, issue and page numbers.
Abstract: The lattice heat capacity of both layered and chainlike compounds has been inferred from an approximation of the vibrational spectrum, which is based upon a pseudoelastic approach. From continuum elasticity theory three modes of vibration are obtained, which are modified by the inclusion of the most dominant dispersion effects. Manageable expressions for the heat capacity are obtained, which were found to be of rather general applicability. They were used to describe the heat capacity of the chainlike diamagnetic ${(\mathrm{C}{\mathrm{H}}_{3})}_{4}$NCd${\mathrm{Cl}}_{3}$, and were found to give an excellent description of the lattice contribution to the heat capacity of a variety of low-dimensional magnetic substances.
TL;DR: In this paper, an experimental MHD generator facility is described, in which cesium-seeded argon is used as a working medium, and the heating of the gas is realized by compression in a shock tunnel.
Abstract: An experimental MHD generator facility is described, in which cesium-seeded argon is used as a working medium. The heating of the gas is realized by compression in a shock tunnel. The enthalpy input into the generator is 5 MW. The test time is 5 msec. The objective of the experiments has been the achievement of electrical energy extractions as high as expected from one-dimensional channel computations. The effects of voltage drops and short-circuiting of the Hall field on the power output are discussed, and the performances of a 3 l and a 10 l channel are examined. In both cases, agreement between the experiment and the theoretical model was found. The 10 l channel yielded an enthalpy extraction of 24 percent with an electrical power density of 140 MW/m/sup 3/.
TL;DR: In this article, heat transfer measurements from a hotwire placed perpendicular to a horizontal air stream, have been made with a constant-temperature anemometer for 0.03 while am and bm are approximately constant, m varies with gas temperature in the same manner as the thermal conductivity of the gas.
TL;DR: An improved procedure for isolating the drugs from serum is given, which results in an extraction recovery of better than 90% for the drugs of interest.
TL;DR: A model of the design process is developed against the background of the evolution of this process, and cybernetics is used as a meta-language to lead to better design results, quantitatively and /or qualitatively.
Abstract: Computer-aided design can be seen as a process in which a careful integration of tje specific characteristics of man and machine is taking place. This integration may lead to better design results, quantitatively and /or qualitatively. The realization of this integration in c.a.d. systems necessitates a renewed and profound analysis of the design process. A model of the design process is developed against the background of the evolution of this process. To this end, cybernetics is used as a meta-language. The development of c.a.d. systems based on this model is discussed.
TL;DR: In this paper, the authors measured resistivity, thermoelectric power and current noise on Li-doped MnO single crystals in the temperature range from 300 to 1000 K.
TL;DR: The transport resistance of a boundary layer is defined, which is independent of the solution in the region of equilibrium and therefore forms a suitable basis to compare facilitated transport with different reaction schemes.
Abstract: The steady-state diffusion of oxygen in layers of hemoglobin solutions takes place under conditions of chemical equilibrium everywhere except in two boundary layers where deviations occur. The transport resistance of a boundary layer is defined in this paper. It is independent of the solution in the region of equilibrium and therefore forms a suitable basis to compare facilitated transport with different reaction schemes. Results are presented for a four-step reaction scheme between oxygen and hemoglobin, and compared with those of a single-step reaction for various reaction rates. The sensitivity of the results to changes in the reaction rates of the four-step model is also studied. With a knowledge of the boundary layer resistance the results of equilibrium calculations can be corrected in a simple way, which allows direct evaluation of experimental results.
TL;DR: In this paper, the electrochemical reduction of nitric oxide at a flow-through mercury-plated nickel gauze electrode in sulphuric acid was investigated and the current efficiencies of hydroxylamine, nitrous oxide and of hydrogen formation were determined.
TL;DR: In this paper, experimental results on the influence of pressure on ice growth are presented, and they are consistent with thermodynamic theory; they also agree with the theoretical analysis of the transport phenomena involved in frozen soils.
Abstract: IN frozen soils water movement towards an ice front can occur, leading to the formation of ice lenses, frost heaving and damage to roads and other structures. During the past decades many attempts have been made to explain the transport phenomena involved, fundamental contributions being made by Everett1 and Takagi2, among others. We present here experimental results on the influence of pressure on ice growth; they accord with thermodynamic theory.