Showing papers by "Delft University of Technology published in 1978"
29 Jan 1978
TL;DR: In this article, a model was developed for the prediction of the dissipation of energy in random waves breaking on a beach and the probability of occurrence of breaking waves was estimated on the basis of a wave height distribution with an upper cut-off which in shallow water is determined mainly by the local depth.
Abstract: A description is given of a model developed for the prediction of the dissipation of energy in random waves breaking on a beach The dissipation rate per breaking wave is estimated from that in a bore of corresponding height, while the probability of occurrence of breaking waves is estimated on the basis of a wave height distribution with an upper cut-off which in shallow water is determined mainly by the local depth A comparison with measurements of wave height decay and set-up, on a plane beach and on a beach with a bar-trough profile, indicates that the model is capable of predicting qualitatively and quantitatively all the main features of the data
1,463 citations
TL;DR: In this paper, the chromatographic activity of the silica surface is discussed on the basis of TMS-phases with various surface coverages, and it is observed that logarithmic retention data for homologous series and different RPphases-partially taken from the literature-form a set of straight lines with a common intersection point.
Abstract: Four different monomeric chemically bonded phases suitable for reversed-phase liquid chromatography have been prepared. Duplicate preparations, elemental analysis, post-treatment with TMS and chromatographic properties all indicate that maximum coverage has been obtained. The chromatographic activity of the silica surface is discussed on the basis of TMS-phases with various surface coverages. It is observed that logarithmic retention data for homologous series and different RP-phases-partially taken from the literature—form a set of straight lines with a common intersection point.
278 citations
TL;DR: In this article, an experimental and numerical study has been made on convective heat transfer in coiled tubes for two boundary conditions: for a uniform peripherally averaged heat flux and for a constant wall temperature.
185 citations
TL;DR: In this article, two families of layer-structure halide perovskites with unbranched organic chains are considered: (C n H 2 n + 1 NH 3 ) 2 MX 4 and NH 3 ( CH 2 ) m NH 3 MX 4 with M = Cd, Cu, Fe, Mn or Pd, X = Br or Cl, n = 1, 2,..., 18, and m = 2, 3,..., 8.
162 citations
TL;DR: In this paper, a method for the isolation of methanol dehydrogenase (alcohol:(acceptor) oxidoreductase, EC 1.8) from Hyphomicrobium X is decribed.
118 citations
DOI•
29 Jan 1978TL;DR: In this paper, a mathematical model concerning the sand concentration and velocity distribution in an oscillatory turbulent flow, with or without resultant current, is presented, and the numerical accuracy of the model has been investigated and diagrams are presented which enable the computation by hand of global velocity profiles.
Abstract: Bakker (1974) developed a mathematical model concerning the sand concentration and velocity distribution in an oscillatory turbulent flow, with or without resultant current. The flow is assumed to be uniform in horizontal direction. The present paper reports on an experimental verification of this theory. Furthermore, the numerical accuracy of the model has been investigated and diagrams are presented which enable the computation by hand of global velocity profiles.
96 citations
TL;DR: In this paper, a model for aeration in shake flasks is presented that enables one to predict whether in the course of an experiment the oxygen supply is becoming a growth-limiting factor or not.
Abstract: The shake flask is a very common and useful tool for the study of submerged fermentations on a small scale. However, the oxygen supply may easily become a limiting factor. A model for the aeration in shake flasks is presented that enables one to predict whether in the course of an experiment the oxygen supply is becoming a growth-limiting factor or not. The results of measurements of the transfer coefficient of a cotton plug and the oxygen mass-transfer coefficient kla are also given.
95 citations
TL;DR: In this article, a large number of compounds with the general formula M(NRIz)n(anion)2 are described and the properties of these compounds are described with the aid of far IR ligand-field and ESR spectra and X-ray powder diagrams.
95 citations
TL;DR: The probability density functions of Freeman codes are given under the assumption that the curve segment may be approximated by a line segment in a grid column (or grid row) to calculate the a priori probability of odd or even Freeman codes.
78 citations
TL;DR: By means of stimulus‐response experiments with a Li+ tracer, a description of the fluid flow in a 30 m3 reactor, used for anaerobic treatment of wastewater, was derived and it was concluded that 60 m3 gas/day were sufficient to provide good mixing and also that the height of the sludge bed should be 2–3 m.
Abstract: By means of stimulus-response experiments with a Li+ tracer, a description of the fluid flow in a 30 m3 reactor, used for anaerobic treatment of wastewater, was derived. It appeared that of the three parts that could be distinguished in the reactor (the sludge bed. The sludge blanket, and the settler), the sludge bed could be described as a combination of two perfectly mixed regions with bypassing and return flows; the sludge blanket was perfectly mixed, while the fluid flow in the settler could be described as plug flow. From experiments performed under different conditions it was concluded that 60 m3 gas/day were sufficient to provide good mixing and also that the height of the sludge bed should be 2–3 m. From this last conclusion it follows, e.g., that scale-up of the 30 m3 reactor should be done by increasing the cross section of the reactor while homogeneously distributing the influent over the bottom.
73 citations
TL;DR: In this article, the double-bond positions and geometry of monoenoic fatty acids were determined from four sections of a core sampled in diatomaceous ooze off the shore of Walvis Bay (S.W. Africa).
TL;DR: In this paper, a point source of liquid was fed into a column of 0.2 m diameter in the absence of a gas stream and the liquid was collected at the bottom of the column in a grid plate consisting of 177 sampling sections.
TL;DR: In this paper, the influence of hydrodynamic environment on the growth phenomena of large potassium dihydrogen phosphate (KDP) crystals has been investigated in a three vessel system and the onset of inclusion formation was paid to the onset.
Abstract: The influence of the hydrodynamic environment on the growth phenomena of large potassium dihydrogen phosphate (KDP) crystals has been investigated in a three vessel system. Special attention was paid to the onset of inclusion formation. Flow visualization experiments carried out in a wind tunnel showed that the flow formed at the rear (downstream) faces of the crystal (i.e. the wake) is a more or less closed circulation system. It appeared that veils of liquid inclusions are not a result of starvation in the laminar boundary layer, as suggested before, but of depletion in the closed wake at the rear.
Der Einflus der hydrodynamischen Umgebung auf die Wachstumserscheinungen groser KDP-Kristalle wurde in einem Dreitanksystem untersucht. Besondere Aufmerksamkeit galt der Einschlusbildung. Beobachtungen im Fliesexperiment in einem Windkanal zeigten, das das Anwartsfliesen an den hinteren Flachen des Kristalls (d. h. der Nachstrom) ein mehr oder weniger geschlossenes Zirkulationssystem darstellt. Die Schleier von flussigen Einschlussen erschienen nicht als Ergebnis der Erschopfung in der laminaren Grenzschicht, wie vorher angenommen wurde, sondern der Erschopfung im geschlossenen hinteren Nachstrom.
TL;DR: In this paper, the synthesis of new coordination compounds of Pt(II) with the nitrogen-donor ligand N-methyl imidazole (NMIz) is described.
TL;DR: In this article, the shape and size of a bubble formed slowly on a sharp-or round-edged orifice are derived with the help of a new analytical solution for the bubble profile.
TL;DR: In this article, the Schleyer force field was used for conformational equilibria in 3,7-substituted bicyclo[3.3.1] nonane derivatives.
TL;DR: In this article, a dc converter with an internal frequency of 50 kHz at an efficiency of 95 percent was described, which provided ohmic isolation between its input and output ports and was experimentally verified that the customary penalty of lowered efficiency at higher levels of frequency could be avoided by the use of series resonant circuits which favor the switching elements.
Abstract: A dc converter is described which processes 1-kW power with an internal frequency of 50 kHz at an efficiency of 95 percent and which provides ohmic isolation between its input and output ports. It was experimentally verified that the customary penalty of lowered efficiency at higher levels of frequency could be avoided by the use of series resonant circuits which favor the switching elements. The output characteristic of the system is that of a voltage limited current source. The road toward development of the technology of reliable and efficient dc converters with yet higher power densities appears possible.
TL;DR: Five morphological types of defective, PBS X-like phage could be distinguished, differing in their tail lengths and in the number of cross-striations on the tail.
Abstract: 72 strains of 24 Bacillus species were induced with mitomycin C. The lysates were examined for the presence of defective phages resembling PBS X in morphology. All strains tested of B. amyloliquefaciens. B, licheniformis, B. pumilus and B. subtilis contained such phages. Five morphological types of defective, PBS X-like phage could be distinguished, differing in their tail lengths and in the number of cross-striations on the tail. The quaternary structure of the tail, the molecular weight of the main tail protein and the antigenic properties of the phages were identical. The killing ranges of the defective phages have been determined and their possible use in taxonomy discussed.
TL;DR: In this paper, a non-destructive method is presented to study the combining properties of a number of hardened cement pastes for NaCl and CaCl 2, and the dependence of the amount of chloride combined by the cement on the total amount added to the cement is calculated.
TL;DR: In this article, the general formula ML2Ox is described, with Ox = oxalato dianion; M = Ni, Co and Zn; 1 = water and imidazoles.
Abstract: Coordination compounds having the general formula ML2Ox are described, with Ox = oxalato dianion; M = Ni, Co and Zn; 1 = water and imidazoles. The compounds are characterised by chemical analyses, i.r., far-i.r., Raman, ligand field and e.s.r. spectra. Magnetic susceptibility measurements at low temperatures indicate a polymeric structure of ant i-ferromagnetically coupled M2+ ions.
TL;DR: In this article, a two dimensional model has been set up of the movements of coarse particles during pneumatic transport in a pipe and an example of a particle cluster consisting of 200 particles moving through a pipe over a distance of five meters has been worked out.
TL;DR: In this paper, empirical force field calculations on conformers of t-butylcyclohexane, cis-and trans-1,4-di-tbutyl cyclohexanes and trans-trans 1,2-di -t-butyclichexane were performed using force fields of Allinger et al.
Abstract: The results are reported of empirical force field calculations on conformers of t-butylcyclohexane, cis- and trans-1,4-di-t-butylcyclohexane and trans-1,2-di-t-butylcyclohexane using the force fields of Allinger et al. (AFF) and of Schleyer et al. (SFF). Comparisons of energy differences and geometric data with experimental values show that both force fields yield useful results; SFF gives the better correlation. The A value of the t-butyl group is calculated to be 4.7 kcal mol−1 (19.7 kJ mol−1). Cis-1,4-di-t-butylcyclohexane and trans-1,2-di-t-butylcyclohexane are predicted to exist as conformational mixtures. The concept of additivity in the prediction of strain energies is discussed.
TL;DR: In this article, the authors described the diffusion-induced behavior of misfit dislocations originally present in the interface of thin bimetallic films and derived an energy criterion for the formation of dislocation walls.
TL;DR: In this paper, RuCl3-impregnated silica by nitrogen-hydrogen tratment at high temperature, up to 700 °C, is superior to calcination of the material prior to reduction.
Abstract: Activation of RuCl3-impregnated silica by nitrogen-hydrogen tratment at high temperature, up to 700 °C, is superior to calcination of the material prior to reduction. Sintering hardly occurs. In addition, activity measurements, based on the liquid phase hydrogenation of benzene, and thermogravimetric analysis suggest a favorable (chemical) interaction between ruthenium and silica.
TL;DR: Curie-point pyrolysis mass spectrometry of the polysaccharide resulted in a spectrum very similar to that of β-1,2-glucan, probably the glucan originates from the fibrillar inner layer of the cell wall.
Abstract: A polysaccharide was isolated from the cell wall of the cyanobacterium Spirulina platensis. Hydrolysis of the polysaccharide only yielded glucose. Curie-point pyrolysis mass spectrometry of the polysaccharide resulted in a spectrum very similar to that of β-1,2-glucan. Probably the glucan originates from the fibrillar inner layer of the cell wall.
TL;DR: In this article, the synthesis and characterisation of dichloro[bis(3,5-dimethylpyrazolyl)methane]nickel(II) s was described.
Abstract: The synthesis and characterisation of dichloro[bis(3,5-dimethylpyrazolyl)methane]nickel(II) s described. At ambient temperature the compound is dimeric with chloro-bridged high-spin five-coordinate NiII
TL;DR: In this article, a reliability analysis of a structural component, i.e., a reactor containment structure, is carried out, and the results are used for the quantification of the risk of nuclear power plants.
TL;DR: In this paper, a compound microscope is described, which consists of a holographic interference microscope and a conventional microscope, and the system combines the highly corrected image and long free working range of microscopy with the large vertical resolution and overall spatial information of interferometry and with the increased depth of imaged volume and potentialities for time sequential observations of holography.
TL;DR: A fast and simple method is introduced that can be used, both manually and in computing, to determine which linear combination of shift-register outputs corresponds to a d-bit delayed version of a maximal-length linear binary sequence.
Abstract: A fast and simple method is introduced that can be used, both manually and in computing, to determine which linear combination of shift-register outputs corresponds to a d-bit delayed version of a maximal-length linear binary sequence. The calculation time is proportional to the logarithm of d. The method is suitable for generating large phase shifts.
TL;DR: In the case that the matrix of a linear complementarity problem consists of the sum of a positive semi-definite matrix and a co-positive matrix a general condition is deduced implying that the Lemke algorithm will terminate with a complementarity solution.
Abstract: In the case that the matrix of a linear complementarity problem consists of the sum of a positive semi-definite matrix and a co-positive matrix a general condition is deduced implying that the Lemke algorithm will terminate with a complementarity solution. Applications are presented on bi-matrix games, convex quadratic programming and multi-period programs.