Generalizing the finite element method: Diffuse approximation and diffuse elements

This paper describes the new diffuse approximation method, which may be presented as a generalization of the widely used finite element approximation method. It removes some of the limitations of the finite element approximation related to the regularity of approximated functions, and to mesh generation requirements. The diffuse approximation method may be used for generating smooth approximations of functions known at given sets of points and for accurately estimating their derivatives. It is useful as well for solving partial differential equations, leading to the so called diffuse element method (DEM), which presents several advantages compared to the finite element method (FEM), specially for evaluating the derivatives of the unknown functions.     

A boundary-element-method formulation for the electromagnetic coupling between dielectric waveguides and resonators

The Boundary Element Method has been applied to evaluate the electromagnetic coupling between dielectric waveguides and resonators. A two-dimensional integral-equation formulation has been developed, using dyadic Green's functions. A numerical solution as a function of electromagnetic and geometrical quantities has been obtained for the scattering parameters of a filtering device, consisting of a Non-Radiative Dielectric waveguide and a pillbox resonator.     

Quantitative estimation of “big” and “little” science interrelation

Qantitative analysis of the interrelation of big and little science on the example of Research and Development of higher education in the USA has been made. The difference in the growth rates of big and little science is explained with the help of scientometric index of capital expenditures per researcher. An attempt has been made to compare the dynamics of efficiency of big and little science on the base of mean duration of a research project. Possibilities of an alternative index of a relative amount of preliminary researches (preprojects) are pointed out.     

Formation of Friction Layers and Wear Resistance of Steels under Conditions of Boundary Friction

We studied the influence of the lubricant compositions Grafitol with 10% graphite (1), Aerol containing 17% MoS₂ (2), Limol containing 60% MoS₂ (3), Limol + 10% chlorine-paraffin (4), and Limol + 10% copper powder (5) on the wear rate and formation of the fine structure of surface friction layers of structural steels. We established a correlation between the tribological characteristics of steels and lubricants. The abrasive wear of 40KhFA steel was minimum if it was lubricated with Limol + 10% copper powder. In this case, its wear was smaller by a factor of 10, 2, 1.25, and 7.25 as compared with lubricant compositions 1–4, respectively. In the course of minimum wear of 40KhFA steel, in the surface friction layers, we observed the minimum values of second-kind distortions (a/a) and of the true size of domains of X-ray coherent scattering (D) as well as the minimum difference between the crystal lattice constants (a) of steel before and after friction.     

Uncertainty of a measured result and confidence error of measurements

An analysis is made of the known information concerning the concepts of error and uncertainty and it is concluded that they are identical.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 14–17, August, 1994.     

Microstructural study of two LAS-type glass-ceramics and their parent glass

The two glass-ceramics studied here derive from the complex system (MgO,ZnO,Li₂O)-Al₂O₃-SiO₂ and are obtained by controlled devitrification of the same parent glass. Although they have the same chemical composition, one is a -quartz (or -eucryptite) type while the other one is a -spodumene glass-ceramic. A detailed microstructural analysis of these materials has been performed at different scales by several complementary characterization methods (SEM, TEM, DTA, XRD and FTIR). This extensive study has shown the great microstructure difference (grain distribution, grain size, nature of vitreous and crystalline phases) between these two glass-ceramics obtained from the same parent glass.     

Critical and Flash Points for Metastable Systems in a Mean-Field Approach

By using, as a model, an analytical equation of state which describes a system that can exist in a liquid or vapor phase, scaling properties regarding the critical temperature and the flash temperature were found. The flash temperature is defined as the highest temperature at which a self-bound system can exist in hydrostatic equilibrium. The flash temperature can provide an alternate natural dimension-dependent scale of temperature, other than the critical temperature.     

Spin hydrodynamic equations with external disturbances and suitable Green's functions for superfluid3He-B. New onsager relations

The spin hydrodynamic equations for superfluid³He-B have been obtained for the case of external, time-dependent fields. On the basis of a microscopic approach, expressions are found for additional terms in equations containing these fields. Considering the linear response of the system to the switching on of external fields, formulas are found for suitable Green's functions (magnetization-magnetization, rotation-rotation, magnetization-rotation, rotation-magnetization). The rotation-rotation Green's function has the 1/q ² singularity characteristic of superfluid systems. Connections between Green's functions lead to relations among kinetic coefficients v, ₁, and ₂. It is also shown that there is a conserved quantityQ ^(B) = div v _s ^(B) that describes sources or magnetic type charges (monopoles) of the superfluid velocity v _s ^(B) . Comparison with the phenomenological approach suggests thatQ ^(B) is proportional to a pseudoscalar giving the projection of the spin density onto the vector describing the axis of rotation.     

The Significance of the MQC Experiment

It is generally agreed that quantum mechanics (QM) describes brilliantly the behavior of matter at the atomic and subatomic level. However, many people, including the author, believe that if it is taken seriously at the level of everyday life, it leads to insuperable difficulties, exemplified by the fate of Schrödinger's unfortunate cat. If, therefore, one is prepared to envisage seriously the possibility that if QM is pushed sufficiently far it may break down or have to be supplemented by some new and currently unforeseeable principle, then the obvious axis along which to try to push it is that which brings us closest to the world of everyday life. Thus, we are motivated to try to define which exact feature most sharply distinguishes those applications of QM at the everyday level that appear paradoxical: to seek, in fact, a quantitative measure of the degree of Schrödinger's-cattiness of various physical situations. Although this is no doubt a subjective question, I explore two plausible candidates: one involving the divergence, in the two branches of the (notional) quantum superposition, of some macroscopic physical quantity; the other invoking the idea of disconnectivitya notion that has much in common with the concept of degree of entanglement currently employed in the context of EPR-Bell-type experiments. Having tried to isolate and define the axis along which we are trying to push QM, I then discuss the main generic obstacles to this program, which may be summarized as (1) quasi-classicality, (2) decoherence, and (3) Franck-Condon suppression. Finally, I emphasize the importance not only of verifying (or not) that QM continues to predict correctly the experimental behavior as we progress along the relevant axis, but of confronting its predictions with those of a class of alternative, macrorealistic theories. I comment on the implications of various possible outcomes to this confrontation.     

Application of inert radioactive gases in the study of solids

The behaviour of different iron salts (FeSO₄.7 H₂O, FeC₂O₄.2 H₂O, Mohr's salt, and basic iron carbonate) was studied by means of the emanation method, DTA and dilatometry. The salts were heated within the temperature range of 20 to 1100 C, under identical conditions. The results obtained are compared and the process of thermal decomposition of the different salts is discussed.The activity of ferric oxide obtained by decomposition of various iron salts is estimated, and it is suggested that the low activity of the sulphate-derived ferric oxides is related to a low thermal annealing rate, while the higher activities of the other two resultant ferric oxides are similarly related to higher thermal annealing rates.     

Pleochroism in thermally-treated acrylic fibres

Acrylic fibres, coloured by inert thermal-treatments up to 573K are highly pleochroic. The preferred absorption is parallel to the fibre axis, implying that the chromophore is a molecular sequence intrinsically part of the oriented polymer chain. The biabsorption, k-k, shows a direct correlation with amount of nitrile reacted in the polymer. Although the development of chromophore is directly related to polymerization of nitriles, the polymerized nitrile sequences themselves may not necessarily be the specific chromophore.Compensated biabsorption, corrected essentially for chromophore concentration, is substantially constant throughout the thermal-treatment, showing that the preferred orientation of both inert chromophore and polymer chain is maintained. An exception arises when light oxidation in air follows inert thermal-treatment, indicating that the oxidation chromophore is oriented perpendicular to the inert chromophore and polymer chain.     

Dual approach to multiple authorship in the study of collaboration/scientific output relationship

This paper presents an empirical study of the relations between scientific output and collaboration performed on two scales: (1) an individual scale, for members of a study model, and (2) a group scale, for three samples varying in the level of productivity. The rank approach was applied in the preparation of the study model resulting in the selection of a set of the most prolific authors. In the course of that process, multiple authorship problem was solved by a dual approach, consisting of normal count and modified straight count procedures. As shown by the analysis of collaborative patterns, either on individual or on group scales, scientific output is highly dependent on the frequency of collaboration among the same authors. Expressed as the collaboration measure, it might serve as an indicator in comparative analyses of scientific productivity in a given field of science.     

The long-range proximity effect: Pair echoes

Recent experiments on N-N-S junctions with high-temperature cuprate superconductors have shown that superconductivity can be induced in the adjacent, normal metal at distances many times greater than the few hundred Ångstroms range of the conventional proximity effect. We show that this arises in the particular geometry used in these experiments through the constructive interference of the tails of the de Gennes-Saint-James bound and quasi-bound states of the normal metal N that penetrate into the third metal, N. This constructive interference results in the re-appearance of a pair amplitude in this metal which is analogous to the spin echo of NMR and which we name a pair echo.     

Ortho-para conversion in hydrogen bubbles in copper

The low-temperature heat release in copper due to ortho-para conversion in hydrogen bubbles is investigated. Deviations from a model of free solid hydrogen are observed: a more intense heat release atT10 K and a rapid (10 h) heat release after cooling to 1.3 K. The experimental results can be explained by the assumption of autocatalytic conversion in the bulk and the catalytic influence of the bubble surface.     

Direct comparison of the loss of load transfer to “E” and “S” glass fibres manufactured by drawing into different environments

Accelerated water uptake tests have been used to compare the onsets of destruction of the ability to transfer shear stress at fibre/matrix interfaces in epoxy matrix glass reinforced plastic (GRP) manufactured with each of four different fibres. The ability to transfer shear stress has been monitored directly by measurement of stress birefringence through and adjacent to individual fibres. Full theoretical and practical details of the experimental method are given. S glass fibres, drawn into an atmosphere of ammonia in an attempt to promote the deposition of primary amines and/or secondary amines, rapidly lose their ability to receive shear stress from the matrix. This is attributed to neutralization of CO₂ by NH₃ within interfacial pockets of dissolved water, and the associated generation of osmotic pressure. Commercial samples of S and E glass fibres and E glass fibres drawn into an atmosphere of ammonia, all survive much larger water uptakes although, in the case of both kinds of E glass fibre, immersion in boiling water eventually gives rise to interfacial pressure pockets. These pressure pockets are also attributed to osmosis, with the role of dissolved solutes tentatively ascribed to the modifying agents present in E glass formulations.     

Fabrication of melt-texture growth YBCO samples using a simple muffle furnace

In our previous work we showed that gradients of temperatureT inside the heating chamber andT/t are the necessary conditions for growing oriented crystal layers inside bulk samples. Using a simple muffle furnace, we have successfully fabricated layers of YBCO samples. Powder layers of Y-123 and Y-211 in different structures were compressed to make sample pellets before heat treatment in order to create internal temperature gradients inside the samples when they were heated. SEM observation proved that the crystal layers grew from both the top and bottom surfaces of the sample independently of the original powder layers before heat treatment. Moreover, we found that the crystal layers are not true layers but bulk crystal with gap lines. EDX analysis confirmed that the 123 and 211 phases coexist in almost all of the samples. Using the concept of internal temperature gradients, we show that it is possible to carry out modified melt-texture growth even in a muffle furnace.     

Investigation of the Serviceability of the Heat Shield of the Orbital Aircraft “Buran” under the Conditions of Radiant Heating on Solar Plants

We have investigated the serviceability of the heatinsulating tiles of the orbital aircraft Buran under radiant heating on an SGU7 solar plant with a mirror concentrator 5 m in diameter. Cycles of aerodynamic heating with a duration of 20 min were simulated. For the total number of cycles for different materials from 20 to 85, the efficiency and serviceability of TZMKtype materials with different coats have been corroborated. The results obtained agree with the test data obtained on gasdynamic (power consumption 1 MW) and radiation (250 kW) test beds, which enables such tests to be recommended for use at preliminary stages in powersaving and ecologically harmless solar furnaces.     

A scientometric assessment of agricultural research in South Africa

This article reports the results of a scientometric assessment of agricultural research in South Africa over the period 1974–1984. The Science Literature Indicators Database of CHI is used and South Africa is compared with 7 other countries spread in America, Asia, Oceania, and Africa. The criteria used for the assessment are the contribution of each country to international agricultural literature (in terms of publications) and their impact in the Schubert-Glänzel-Braun Impact Scale. It was found that, although the South African contribution has improved in that period, it is comparable to that of Brazil and Argentina; that Nigeria and Israel produce 3 times more, and: that Australia and Canada contribute more than one order of magnitude of publications more than South Africa. As far as research impact is concerned Plant Science research in South Africa is rated fair in the Schubert-Glänzel-Braun scale, whilst Dairy and Animal Science and Veterinary research are rated poor.     

A novel X-ray technique for inspection of steel pipes

The corrosion-induced material loss in crude oil carrying steel pipelines was originally studied by making use of the backscatter X-ray technique. The steel thickness can be determined by studying the density profile of the backscatter intensity vs. the depth location of a voxel. There are, however, some practical limitations to the above method, and a new method for evaluating steel thickness, namely, the transcatter technique is described. This technique uses the intensity of the beam which is transmitted by the pipe wall and subsequently scattered by the hydrocarbon inside the pipeline. The thickness is evaluated using three techniques, namely, the sequential technique, the dual angle technique, and the reference technique. Of the three techniques, the sequential technique has been studied in detail. The mathematical equations and experimental results related to the transcatter technique show that the thickness can be measured with an accuracy of better than 10% for a nominal steel thickness of 8 mm with a measurement time of several minutes.     

Relationship between superconductivity and band structures of electrons and phonons

The relationship between superconductivity and band structures of electrons and phonons is established on the basis of a generalized Bardeen-Cooper-Schrieffer model in which the interaction strengths (V ₁₁,V ₁₂,V ₁₂) among and between electron (1) and hole (2) Cooper pairs are differentiated. Elemental superconductors must have local hyperboloidal Fermi surfaces called necks or inverted double caps.