Showing papers by "Eindhoven University of Technology published in 1984"
TL;DR: The distance between a system (A, B ) and the set of uncontrollable systems is the minimum of the smallest singular value of [λ I − A, B ] with respect to λ.
202 citations
01 Jul 1984
TL;DR: In this paper, experimental investigations regarding composition and properties of the surface layer of concrete, indicated as concrete skin, have been executed, from theoretical considerations, an (optimistic) estimate has been made of such skin properties.
Abstract: Some experimental investigations regarding composition and properties of the surface layer of concrete, indicated as concrete skin, have been executed. On the other hand, from theoretical considerations, an (optimistic) estimate has been made of such skin properties.
160 citations
TL;DR: In this paper, a computer program based on the use of Gaussian expressions for the x-ray distribution with depth curves was tested on its useful for quantitative electron probe microanalysis, and the results showed that the +(pz) approach is indeed very promising as a narrow histogram with an r.m.s. value of 5.4% could be produced.
Abstract: A computer program based on the use of Gaussian expressions for the x-ray distribution with depth [+(pz) curves] was tested on its usefulnw for quantitative electron probe microanalysis. As the good results originally claimed for a similar program could not be reproduced initiaUy, it was subjected to a detailed analysis. As a result, some modi6cations in the approach are proposed. Apart from increasing the speed of calculation considerably, the modified expressions provide a better insight into the delicate balance which has to exist between the relevant quantities involved. After a new optimization process the modified program was tested on about 450 published microanalyses. The results show that the +(pz) approach is indeed very promising as a narrow histogram with an r.m.s. value of 5.4% could be produced. Finally, some suggestions are made for future improvements.
126 citations
TL;DR: In this paper, the reducibility of platinum on γ-Al2O3- and TiO2 was studied with the aid of temperature programmed reduction, and the reduction peak temperature was found to be dependent on the temperature of the primary oxidation after impregnation and drying.
121 citations
TL;DR: In this paper, the acidity and activity of zeolite H-ZSM-5 were analyzed using NH3-t.p.d. and n-hexane cracking.
97 citations
TL;DR: In this paper, the fluidization behavior of cracking catalyst has been studied up to pressures of 15 bar with different fluidization gases (Ar, N 2, H 2 ), and the experimental results reveal that the minimum fluidization velocity (U mf ) is independent of the pressure.
82 citations
TL;DR: In this article, the diffusion coefficients of helium, hydrogen, oxygen and nitrogen in water have been determined from the permeability of a stagnant liquid layer in the quasi-steady state (SLL method).
77 citations
TL;DR: In this paper, a new basic bubble parameter, J, has been introduced, which accounts for the bubble behavior, and it has been found that J = a 1 i h 1 and J /( J 0 − J ) = a 2 v h 2 where J 0 = J at v = 0 ms −1 and a 1, a 2 h 1, and h 2 are empirical constants; some of these depend on nature of gas evolved.
69 citations
67 citations
01 Jan 1984
TL;DR: A controllability measure in terms of the distance between a system and the set of uncontrollable systems is developed and some properties of a minimal disturbance, rendering a system noncontrollable, are given.
Abstract: A controllability measure in terms of the distance between a system and the set of uncontrollable systems is developed. Some properties of a minimal disturbance, rendering a system noncontrollable, are given.
65 citations
TL;DR: In this paper, a brief survey of the properties of InSb quantum wells is reported, and the energy level scheme is described on the basis of a square-well model taking into account the pronounced non-parabolicity of the conduction band.
Abstract: A brief survey of the properties of InSb quantum wells is reported. The energy level scheme is described on the basis of a square-well model taking into account the pronounced non-parabolicity of the conduction band. A simple model for electron transport with polar optical mode scattering is presented. The temperature dependence of the low-field electron mobility is calculated for various well-widths. Threshold fields for negative differential resistance and for energy runaway are estimated. Threshold energies for impact ionization, including resonance effects involving the electronic sub-bands are also obtained. Novel features expected of InSb quantum wells are summarized and discussed.
TL;DR: In this paper, two explanations for the Meyer-Neldel rule in inorganic semiconductors are given: the freezing-in of donor acceptor type defects can lead to this rule both for band conductors and for small-polaron hopping conductors.
TL;DR: In this paper, the reaction order in zincate was found to be +1.3± 0.8 in the anodic and −0.8 ± 0.2 in the cathodic direction.
TL;DR: A review on collisional-radiative models in plasmas is given in this paper, where a numerical model applied to the argon neutron system and an analytical model for ionizing plasma are treated in more detail.
Abstract: A review on collisional-radiative models in plasmas is given. Work of Fujimoto (1980), Biberman et al., (1969), Drawin (1965) and Seaton (1959) has been an important guide to this review. Ionizing, recombining and equilibrium plasmas are dealt with. Attention has been paid to the classification of CR models in phases, such as corona phase, excitation saturation phase (ESP), capture radiative cascade (CRC) phase and partial local thermal equilibrium (PLTE). A numerical model applied to the argon neutron system and an analytical model applied to the ESP and PLTE for ionizing plasma are treated in more detail
TL;DR: In this article, the authors used conjoint measurement to estimate consumer utility functions and a multivariate logit model as an approximation of the unit multivariate normal distribution is used to predict the probability that a consumer will choose a particular shopping centre.
Abstract: In this paper the authors are concerned with the application of conjoint measurement models to predict consumer choice of shopping centres. First, conjoint measurement models are discussed in the context of the development of spatial shopping-models. Next, the conceptual framework underlying the model and conjoint measurement are discussed. The second part of the paper describes an application of the methodology. Conjoint measurement is used to estimate consumer utility functions and a multivariate logit model as an approximation of the unit multivariate normal distribution is used to predict the probability that a consumer will choose a particular shopping centre. The results indicate that the methodology offers a potentially valuable approach to the modelling of spatial shopping-behaviour.
TL;DR: The parameter tau 1, governing the fast viscous phenomena, is found to be subject to the largest errors.
Abstract: Using the quasi-linear viscoelastic model proposed by Fung for the description of the viscoelastic properties of soft biological tissues, the parameters governing their time-dependent behavior are commonly estimated from relaxation experiments. Exact quantification is possible from the response to a step change in the strain. Since it is physically impossible to realize a true step change in the strain, in practice the response to a steplike strain change is used. In the present study the discrepancies between the exact and the estimated parameter values are investigated using a hypothetical quasi-linear viscoelastic material. The parameter tau 1, governing the fast viscous phenomena, is found to be subject to the largest errors. Methods for obtaining better estimates of tau 1 are outlined in a number of special cases.
TL;DR: By using a new constructive method, it is shown that σ(n, p) ⩽ (p − t + 1)pn−r, where p is a prime and n = 1 + t(p r−1 − 1) (p - 1) for some integers t and r.
TL;DR: In this article, the structural properties of rhodium crystallites were determined after reduction with H{2, evacuation at elevated temperatures, CO admission at room temperature, CO desorption, and admission at 523 K (at which temperature the Boudouard reaction takes place).
TL;DR: The only q-subsets of GF(q2) with the property that the difference of any two elements is always a square or always a non-square, are the lines of GF (q2), considered as the affine plane AG(2,q).
TL;DR: In this paper, the kinetics of oxygen reduction on thick layers of iron phthalocyanine (FePc) in alkaline medium were studied using the rotating ring-disc electrode, and it was found that oxygen is almost exclusively reduced directly to OH −, and only in a narrow potential range is some HO − 2 formed as well.
TL;DR: In this article, the retetnio behavior of starch and cellulose hydrolysates on alkyl-modified silica columns using aqueous eluents has been studied.
TL;DR: In this paper, a mathematical model of a SEM-EBIC experiment devised to measure the diffusion length of semiconductor materials is presented, where the injected minority carriers diffuse through the material and recombine in the bulk at a rate proportional to their local concentration.
Abstract: This paper deals with a mathematical model of a SEM-EBIC experiment devised to measure the diffusion length of semiconductor materials. In the model the semiconductor material occupies a half-space, of which the plane bounding surface is partly covered by a semi-infinite current-collecting junction, the Schottky diode. A scanning electron microscope (SEM) is used to inject minority carriers into the material. It is assumed that injection occurs at a single point only. The injected minority carriers diffuse through the material and recombine in the bulk at a rate proportional to their local concentration. Recombination also occurs at the free surface of the material, not covered by the junction, where its rate is determined by the surface recombination velocity v. The mathematical model gives rise to a mixed-boundary-value problem for the diffusion equation, which is solved by means of the Wiener-Hopf technique. An analytical expression is derived for the measurable electron-beam-induced current (EBIC) caused by the minority carriers reaching the junction. The solution obtained is valid for all values of v, and special attention is given to the limiting cases v=∞ and v=0. Asymptotic expansions of the induced current, which are usable when the injection point is more than a few diffusion lengths away from the edge of the junction, are derived as well.
TL;DR: The recently introduced modified Gaussian φ(ϱz) approach is compared with three other correction procedures for quantitative electronprobe microanalysis and the Love-Scott correction model performs equally well and are both superior to the Ruste and ZAF correction models.
Abstract: The recently introduced modified Gaussian φ(ϱz) approach is compared with three other correction procedures for quantitative electronprobe microanalysis. On the basis of results obtained for 441 published microanalysis data it is concluded that the modified Φ(ϱz) approach and the Love-Scott correction model perform equally well and are both superior to the Ruste and ZAF correction models. Special attention has been paid to the new atomic number correction proposed by Love et al. It was found to be only marginally better than that of the Φ(ϱz) approach.
TL;DR: In this paper, the possibilities, limitations and quantitative performance of dynamic headspace sampling, in particular closed-loop stripping, were investigated for various classes of organic substances in aqueous samples with concentrations down to the parts per 1012 (ppt) level.
TL;DR: In this paper, temperature-programmed reduction (TPR) shows that these catalysts are almost completely oxidized during passivation, which leads to ultradisperse systems (H/Rh > 1.0).
TL;DR: In this paper, it was proved that the cardinality of a 2-distance set S in Euclidean d-dimensional space satisfies cards(S )≤ ½(d + 1/(d + 2) ).
Abstract: It is proved that the cardinality of a 2-distance set S in Euclidean d -dimensional space satisfies cards( S )≤½( d +1)( d +2).
TL;DR: In this paper, the heat capacity and nuclear spin-lattice relaxation of a quasi-one-dimensional compound (Cu${\mathrm{Br}}_{3}$) have been measured for 1.5 $KlTl7$ K and magnetic fields up to 7 kG.
Abstract: The heat capacity and nuclear spin-lattice relaxation of the quasi-one-dimensional compound (${\mathrm{C}}_{6}$${\mathrm{H}}_{11}$${\mathrm{NH}}_{3}$)Cu${\mathrm{Br}}_{3}$ have been measured for 1.5 $KlTl7$ K and magnetic fields up to 7 kG. All data are in good agreement with classical soliton theory, both for in-plane and inclined fields, yielding the first evidence of solitons in a ferromagnetic quantum $\mathrm{XY}$ chain.
TL;DR: In this paper, a comparative analysis conducted to assess the validity of magnitude estimation, conjoint measurement, and functional measurement for specifying and evaluating residential utility functions was carried out and the results of the analysis suggest that all three measurement procedures may be used to evaluate an individual's evaluations of attributes of residential environments and to identify overall evaluations.
Abstract: This research note presents the main findings of a comparative analysis conducted to assess the validity of magnitude estimation, conjoint measurement, and functional measurement for specifying and evaluating residential utility functions. The results of the analysis suggest that all three measurement procedures may be used to evaluate an individual's evaluations of attributes of residential environments and to identify overall evaluations. In addition, the results support the view that multiplicative models perform slightly better than additive models in terms of capturing the way in which subjects integrate part-worth utilities into some overall measure of utility or evaluation.
TL;DR: In this paper, the authors investigated the shear band formation at glass beads embedded in a polycarbonate matrix subjected to a uniaxial tension by microscopic in situ observation.
Abstract: The shear band formation at glass beads embedded in a polycarbonate matrix subjected to a uniaxial tension has been investigated by microscopic in situ observation. The degree of interfacial adhesion was varied by different glass surface treatments. To gain insight into the three-dimensional stress field requirement for shear band formation, the distributions of several elastic failure criteria around an isolated adhering glass sphere in a polycarbonate matrix have been computed with the aid of finite element analysis. It was found that the mechanism for shear band formation is fundamentally different for adhering and non-adhering glass beads. In the case of excellent interfacial adhesion, the shear bands form near the surface of the bead in regions of maximum principal shear stress and of maximum distortion strain energy. In the case of poor interfacial adhesion, shear band formation is preceded by dewetting along the interface between bead and matrix.