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141.
142.
This paper describes an efficient, accurate and simple implementation of an algorithm for generation of quadrilateral finite element meshes. An original algorithm by Talbert and Parkinson [J.A. Talbert, A. Parkinson, Development of an automatic two-dimensional finite element mesh generator using quadrilateral elements and Bezier curve boundary definition, Int. J. Numer. Meth. Eng., 29 (1990) 1551–1567], has been substantially redeveloped and modified and presented in greater detail. We cover several important issues omitted in publication mentioned and we will provide interested readers with fully documented source code of the program. 相似文献
143.
The thermal and mechanical properties of carbon, glass and Kevlar fibre reinforced epoxy composites are discussed, with particular reference to the behaviour of these materials at cryogenic temperatures. The effects of production techniques and various fibre arrangements are determined. 相似文献
144.
Juan M. C. Tascn A. M. Olga Olivn Luis G. Tejuca 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1986,36(3):136-143
Some aspects of the interactions of CO and NO with LaRhO3 have been studied. The reduction of this oxide with CO occurs where the contracting sphere model is of perovskite structure stable up to a concentration of anion vacancies of ca. 2e? per molecule. By reduction of LaRhO3 at 817 K, rhodium was obtained, highly dispersed on a matrix of La2O3. After a reduction-oxidation cycle at 871 K the particle size of the perovskite decreased drastically. The activation energy of the reduction (67 kJ mol?1) was significantly lower than that of other LaMO3 oxides of group-VIII metals. Coverages of CO(θCO) and NO(θNO) at room temperature were lower than 3%, θNO being substantially higher than θCO. The reversibly adsorbed fractions of CO and NO underwent a remarkable decrease after preadsorbing NO and CO, respectively. This competitive adsorption is assumed to be associated with the adsorption of CO and NO on metallic sites. NO preadsorption inhibited the total adsorption of CO more severely than the reverse, indicating that NO is bound more strongly than CO to the LaRhO3 surface. 相似文献
145.
During the last ten or fifteen years we have seen an increase in enrollment in undergraduate psychology courses that is far out of proportion to the general increase in overall university attendance. Psychology departments are overwhelmed with undergraduate students, and the numbers continue to increase each year. Since we are allocating so much of our time, energy, and resources to undergraduate teaching, it is important to determine what these students are being educated for. This note reports the results of an inquiry into the postgraduate occupations of the members of the first three graduating classes of the psychology major programme at McGill University. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
146.
The onset of superconductivity due to fluctuations of the order parameter is investigated in the presence of a surface. The onset of the Meissner effect is calculated in close analogy to the Landau diamagnetism of a free-electron gas, both phenomena being due to surface currents. In the framework of the static Ginzburg-Landau theory the current density induced by a magnetic field parallel to the surface is calculated as function of the distance from the surface. It is shown that for magnetic fields above the surface-nucleation fieldH
c3 the integrated current density is the same for the two boundary conditions of vanishing order parameter and vanishing order-parameter derivative at the surface, and leads to the bulk expression for the fluctuation magnetization. Using the time-dependent Ginzburg-Landau theory, the dynamical conductivity in the surface sheath is calculated. Apart from numerical factors of order unity, the surface-sheath conductivity is found to diverge on approachingT
c3 in the same manner as the conductivity of a thin film diverges on approaching the bulk transition temperature, and is isotropic in contrast to the bulk case in the presence of a magnetic field. 相似文献
147.
G. M. Hartwig 《Journal of the American Oil Chemists' Society》1968,45(10):661-665
The disappearance of foam when increments of soil are added is frequently used to assess the foam performance of surfactants
in dishwashing. A small scale screening test has been published using a Terg-o-tometer to generate foam and disperse the soil.
However, the end point is difficult to determine visually because of the violent agitation of the surface. A method has been
developed, whereby the surface foam reflectance is automatically and continuously recorded from four beakers of surfactant
solution simultaneously. Near the end point, the rate of foam disappearance is determined and the complete foam disappearance
can be interpolated from the instrumental recorded curves. Comparisons are given for experienced operator and instrumentally
determined end points which are shown to be in agreement. 相似文献
148.
Korotkova O Wolf E 《Journal of the Optical Society of America. A, Optics, image science, and vision》2004,21(12):2382-2385
The complex spectral degree of coherence of a general random, statistically stationary electromagnetic field is introduced in a manner similar to the way it is defined for a beamlike field, namely, by means of Young's interference experiment. Both its modulus and its phase are measurable. We illustrate the definition by applying it to blackbody radiation emerging from a cavity. The results are of particular interest for near-field optics. 相似文献
149.
Guasch-Jané MR Ibern-Gómez M Andrés-Lacueva C Jáuregui O Lamuela-Raventós RM 《Analytical chemistry》2004,76(6):1672-1677
Presented in this paper is a new method for the identification of tartaric acid as a wine marker in archaeological residues from Egyptian vessels using liquid chromatography with mass spectrometry in tandem mode (LC/MS/MS). Owing to the special characteristics of these samples, such as the dryness and the small quantity available for analysis, it was necessary to have a very sensitive and highly specific analytical method to detect tartaric acid at trace levels in the residues. Furthermore, an alkaline fusion was carried out to identify syringic acid derived from malvidin as a red wine marker, in a deposit residue from a wine jar found at the tomb of king Tutankhamun. Malvidin-3-glucoside, the main anthocyanin that gives young wines their red color, polymerizes with aging into more stable pigments. However, the presence of malvidin in ancient residues can be proved by alkaline fusion of the residue to release syringic acid from the pigment, which has been identified, here for the first time, by using the LC/MS/MS method revealing the red grape origin of an ancient Egyptian wine residue. 相似文献
150.
Robert?C.?Soliva-Fortuny Olga?Martín-BellosoEmail author 《European Food Research and Technology》2003,217(1):4-9
Fresh-cut Conference pears were packaged under different modified atmosphere packaging (MAP) conditions and stored in refrigeration. The effects of packaging atmospheres on the microbial viability as well as on the changes in acidity, sugars and ascorbic acid (AA) were studied throughout storage. The use of plastic bags of a permeability of 15 cm 3 O 2 m -2bar -1 24 h -1 and initial atmospheres of 0 kPa O 2 extended the microbiological shelf life of pear cubes for at least 3 weeks of storage. Under these conditions, AA levels were kept almost unvaried throughout storage due to the restrictions in the O 2 availability inside the bags' headspaces. However, these conditions also triggered physiological and biochemical changes that caused greater changes in the product acidity. The sugar profile was also affected by storage, but MAP did not show any significant influence on the reported changes. 相似文献