The neural net of neural network research

In this paper we discuss the limits and potentials of bibliometric mapping based on a specific co-word analysis. The subject area is neural network research. Our approach is a simulation of expert assessment by offering the reader a narrative of the field which can be used as background information when reading the bibliometric maps. The central issue in the applicability of bibliometric maps is whether these maps may supply additional intelligence to users. In other words, whether such a bibliometric tool has an epistemological value, in the sense that it ecriches existing knowledge by supplying unexpected relations between specific pieces of knowledge (synthetic value) or by supplying unexpected problems (creative value). We argue that sophisticated bibliometric mapping techniques are indeed valuable for open new avenues to study science as a self-organizing system in the form of a neural network like structure of which the bibliometric map is a first-order aproximation. In that sense, this paper deals with the neural net of neural network research as our bibliometric techniques in fact mimic a connectionistic approach.     

Anisotropic spin diffusion and multiple spin echoes in3He-4He solutions

We propose a ₁-t₁-₂ pulse-NMR experiment to detect the spin-diffusion anisotropy, =D-D, in degenerate spin-polarized³He-⁴He mixtures, where D and dare the transverse and longitudinal spin diffusion coefficients. In such an experiment the nonlinearity of the dynamics produces multiple spin echoes (MSE). At the ³He concentration x₃ 4% the spinrotation parameter vanishes (M 0), so that the nonlinearity of the equations of motion is entirely due to the anisotropy. In this situation, detection of MSE amounts to observation of D. For slight anisotropy, i.e. D/D 0.25, we use a perturbation scheme similiar to that developed by Einzel et al. (in that case, for small M and small demagnetizing field) to calculate the second and third echo heights. For larger anisotropy we numerically calculate the echo heights. We find that for D/D = 0.5 the heights are 2 % of the first echo, and should be detectable. The (₁, ₂) tip-angle dependence of the D echoes is different from that of the M and demagnetization echoes, and furthermore, they occur at right angles to these echoes (in spin space). Thus, even when small spin-rotation and demagnetization effects are present, the ₁-t₁-₂ experiment provides a sensitive means of detecting the anisotropy.     

Strength distributions and size effects for 2D and 3D composites with Weibull fibers in an elastic matrix

Monte Carlo simulation and theoretical modeling are used to study the statistical failure modes in unidirectional composites consisting of elastic fibers in an elastic matrix. Both linear and hexagonal fiber arrays are considered, forming 2D and 3D composites, respectively. Failure is idealized using the chain-of-bundles model in terms of -bundles of length , which is the length-scale of fiber load transfer. Within each -bundle, fiber load redistribution is determined by local load-sharing models that approximate the in-plane fiber load redistribution from planar break clusters, as predicted from 2D and 3D shear-lag models. As a result the -bundle failure models are 1D and 2D, respectively. Fiber elements have random strengths following either a Weibull or a power-law distribution with shape and scale parameters and , respectively. Under Weibull fiber strength, failure simulations for 2D -bundles, reveal two regimes: When fiber strength variability is low (roughly >2) the dominant failure mode is by growing clusters of fiber breaks, one of which becomes catastrophic. When this variability is high (roughly 0<<2) cluster formation is suppressed by a dispersed failure mode due to the blocking effects of a few strong fibers. For 1D -bundles or for 2D -bundles under power-law fiber strength, the transitional value of drops to 1 or lower, and overall, it may slowly decrease with increasing bundle size. For the two regimes, closed-form approximations to the distribution of -bundle strength are developed under the local load-sharing model and an equal load-sharing model of Daniels, respectively. The results compare favorably with simulations on -bundles with up to 1500 fibers.     

Some social-psychological aspects of becoming a physicist

A group of academic scientists and a group of industrial scientists in the field of solid state physics are compared with regard to their view of the physicist in general. In the same way two groups of students in different phases of their training are interviewed in order to get insight into social conflicts present in the educational system. Differences between the groups are found in the importance they attach to the social aspect of the research and in the degree to which they feel the physicist to be a normative concept.     

The morphology of α′ martensite in a two-phase (α+γ) Fe-Cr-Ni stainless steel

Both lath-shaped and martensites are induced by tensile deformation within of a two-phase ( + ) Fe-Cr-Ni stainless steel, forms from the through the at an intersection of two crystals. These are observed both when is surrounded by and when borders . The amount of strain at which both and nucleate, increases with test temperatures in the range –196 to 50° C. Adjacent laths are either twin-related, or 5, 9, 15 or 19° off the twin relationship, as found by analysing electron diffraction patterns.     

Solution of thermal conductivity problems with boundary condition of the third kind and arbitrary coordinate and time dependence of the biot number

An analytical solution of the thermal conductivity problem with boundary conditions of the third kind and arbitrary coordinate and time dependence of the Biot number is found in the form of a converging series of quadratures.Notation , z dimensionless coordinates - dimensionless temperature - Q dimensionless volume heat-liberation density per unit time - Fo=/² Fourier number - Bi₁(, Fo)=(, Fo) · / Biot number - thermal diffusivity coefficient - plate thickness - time - (, Fo) heat-liberation coefficient - thermal conductivity coefficient - i summation index - Jo zero order Bessel function of the first kind Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 41, No. 3, pp. 536–540, September, 1981.     

A fuzzy set theory approach to national composite S&;T indices

Summary Composite science and technology (S&T) indices are essential to overall understanding and evaluation of national S&T status, and to formulation of S&T policy. However, only a few studies on making these indices have been conducted so far since a number of complications and uncertainties are involved in the work. Therefore, this study proposes a new approach to employ fuzzy set theory and to make composite S&T indices, and applies it. The approach appears to successfully integrate various S&T indicators into three indices: R&D input, R&D output, and economic output. We also compare Koreas S&T indices with those of five developed countries (France, Germany, Japan, the United Kingdom, and the United States) to obtain some implications of the results for Koreas S&T.     

A bibliometric profile of top-scientists a case study in chemical engineering

We carefully selected a group of chemical engineering scientists internationally recognized as top-scientists in their field. A method has been developed to systematically compare bibliometric characteristics of these top-scientists with an average scientist in chemical engineering. This method also includes citation-analysis of books and proceedings. The results show a very clear bibliometric profile. First, top-scientists references are more numerous and, fourth, they concern more recent literature. Our fifth findings is that the journals used by top-scientists for their publications are representative for the field of chemical engineering as a whole. But they differ in specific aspects significantly from the average journal structure in chemical engineering: the published work of top-scientists is both general as well as more specialistic than the average work in chemical engineering.     

Scientometric analysis of the research activities of chemists from the “Rugjer Bošković” Institute (Yugoslavia), 1976–1985

The research activity of chemists from the Rugjer Bokovi Institute (RBI, Zagreb, Yugoslavia) was analyzed for the period 1976–1985, covering 2018 research years of scientific work, and 1149 SCI registered papers (0.57 publications per research year). At the average, one paper was published by 3.05 scientists. The papers were published in 235 different journals, most frequently is the nationalCroatica Chemica Acta (171 papers). The publications were divided into two groups: for the periods 1976–1980 and 1981–1985, and for each paper citations were collected in the respective time period. An average publication had 2.58 citations. Chemical papers from the second period had 2.73 citations per paper, which is 85% of the expected value, and this was considerably more than for Yugoslav papers (66%) in general. The papers were classified according to the subfields used in theJournal Citation Reports, and the results compared with the data published bySchubert, Glänzel andBraun. The distribution of citations was also analyzed.     

High-frequency dielectric behaviour of polycrystalline zinc substituted cobalt ferrites

The dielectric constant () and complex dielectric constant () of zinc substituted cobalt ferrites have been measured at room temperature in the high frequency range 100 kHz to 1 MHz. The values of dielectric loss tangent (tan ) have been computed from and . Plots of dielectric constant () versus frequency show a normal dielectric behaviour of the spinel ferrites. The frequency dependence of dielectric loss tangent (tan ) is found to be abnormal, giving a peak at certain frequency for all the ferrites under investigation. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. The dielectric constant for these mixed ferrites is approximately inversely proportional to the square root of the resistivity. A plot of dielectric constant versus temperature shows a transition near the Curie temperature. An attempt is made to explain the possible mechanism for this observation.     

Use of adjoint functions in investigations of heat conduction and transfer processes

An examination is made of the use of adjoint functions in heat conduction and convection theory. Formulas of perturbation theory are obtained for steady and unsteady cases, an interpretation of the physical meaning of adjoint temperature is given, and some applications of the theory are discussed.Notation (r,) thermal conductivity - t(r,) temperature - t *(r,) adjoint temperature - q_V(r,) density of heat release sources - p(r,) a parameter of adjoint equation - r generalized coordinate - time - (r_s, ) heat transfer coefficient - I linear functional of temperature - (r,;r₀,₀) and *(r,; r₀,₀) Green's function for t(r, ) and t *(r, ) - C(r,) volume specific heat - W(r, ) vector distribution of flow velocities - V, S volume and surface areas of body - R radius of HRE - r, radial and angular coordinates - F_in, F_out inlet and outlet flow areas of channel     

Thermal stability of the αZn–Mg2Zn11 and αZn–βAl eutectics obtained by Bridgman growth

The thermal stability of rod-like Zn–Mg2Zn11 and lamellar Zn–Al eutectics obtained by Bridgman growth of Zn–3.1 wt% Mg and Zn–5 wt% Al has been studied for soaking times up to 10 h at 300 and 350°C, respectively. Two-dimensional coarsening resulted for Zn–Mg2Zn11 grown at 0.5 and 1 mm s-1 while fault migration was operative for lamellar Zn–Al grown at 0.1 and 1 mm s-1. Hardness decreased with increased soaking time according to a Hall–Petch relationship with mean interphase spacing and the values H0 and kY accord well with the values obtained from the Hall–Petch relationship for HV of as-solidified Zn–Mg2Zn11 and Zn–Al with eutectic interphase spacing, respectively. © 1998 Chapman & Hall     

Specific analysis of EBSD data to study the texture inheritance due to the β → α phase transformation

A specific processing of EBSD data is proposed to study the texture inheritance of titanium or zirconium alloys. A non standard misorientation map is calculated to localise the colonies inherited from the same parent grain. The calculation of the parent orientation from its inherited variants detailed in previous works has been adapted to the data obtained from an automated EBSD analysis. Finally, a method to derive the orientation map of the parent phase from that of the inherited phase is proposed. The resulting and COMs are used to study some aspects of the variant selection occurring in the transformation of a T40 sample.     

Investigations of the copper isotope effect in oxygen-deficient YBa2Cu3O7−δ

We present data on the copper isotope effect (⁶³Cu-⁶⁵Cu), C_u =-nT_c/nm_Cu, for two isotopic pairs of oxygen-deficient YBa₂Cu₃O_7–, where varies between 0.06 and 0.52. _Cu is below 0.01 at =0.06 (fully oxygenated), it takes values between –0.14 and –0.34 in the 60 K plateau. Larger negative values of _Cu are observed away from the plateau. The dependence of _Cu is similar to that of the pressure effect dnT_c/dP.     

Grain growth in the two-phase Al-Cu alloys

Grain and phase growth in the two-phase Al-Cu alloys containing 6, 11, 1 7, 24 and 33 wt % Cu were investigated by annealing at 535 °C for 0.5–100 h. The grain and phase sizes of the phase are seen to be larger than that of the phase. The size of phase decreases whereas the size of phase increases with increasing copper content in the alloy. As such, the phase- and grain-size distributions are broader than the phase- and grain-size distributions, but the size range depends on annealing time and alloy composition. The grain sizes of the ,d , and ,d , phases can be related to the volume fraction of the phase,f , according to the equationd = 0.497d /f .     

Morphological and crystallographic features of γ-γ′ Ni-Al and Ni-Al-Ti two-phase bicrystals

Several- Ni-Al and Ni-Al-Ti two-phase bicrystals were made by the solid-state diffusion couple method. Each couple consisted of a-phase single crystal and a pure-Ni polycrystal, and was annealed at 1473 K in an Ar gas atmosphere. Single crystal layers of-phase with uniform thickness always grow into the parent-phase single crystals. The resultant/ interface has no voids or facets regardless of the orientation of interface and the chemical composition of the-phase. Porosity formation due to the Kirkendall effect is observed in the diffused region. Concentration profiles exhibit nearly constant gradients in-phase. The orientation relationship between both phases is found to be 001//001, that is, the-phase grows epitaxially along the crystal orientation of-phase.     

Thermal conductivity of hydrocarbons in the naphthene group under high pressures

The thermal conductivity of hydrocarbons in the naphthene group has been experimentally determined. An equation is now proposed for calculating the thermal conductivity over the given temperature and pressure ranges.Notation thermal conductivity - ₂₀ and ₃₀ values of the thermal conductivity at 20 and 30°C, respectively - t₀,P₀ thermal conductivity at t₀, p₀ - _t p thermal conductivity at temperature t and under pressure P - change in thermal conductivity - P pressure - P_melt melting pressure - P₀ atmospheric pressure - t₀ 20°C temperature - T, t temperature - T_cr critical temperature - temperature coefficient of thermal conductivity - ₂₀ temperature coefficient of density - density - ₂₀ density at 20°C - _cr critical density - M molar mass - =T/T_cr referred temperature - v specific volume - v₀ specific volume at 20°C - v change in specific volume - _{3 0} a coefficient - B (t) a function of the temperature - S a quadratic functional - W_i, weight of the i-th experimental point - _i error of the i-th experimental value of thermal conductivity - B _{y, =0.6} value of B (t) at T = 0.6T_cr - B = B (t)/B_{, =0.6} referred value of coefficient B (t) Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 41, No. 3, pp. 491–499, September, 1981.     

Plane thermal stresses around holes under steady distribution of temperature

Summary A method for determining the plane thermal stress distribution in a multiply connected region under steady distribution of temperature is presented. The analysis is based on the complex variable approach and permits, if the thermal field is known, the simple determination of theKolosoff functions. The method is illustrated using two examples.

---

Zusammenfassung Es wird eine Methode zur Bestimmung des ebenen Wärmespannungszustandes in einem mehrfach zusammenhängenden Bereich unter stationärer Temperaturverteilung angegeben. Die Analyse benützt die komplexe Darstellung und erlaubt die einfache Bestimmung derKolosoff-Funktionen, wenn das Temperaturfeld bekannt ist. Die Methode wird anhand von zwei Beispielen illustriert.

---

Notation c constant which take valuesc=E/(1–) for plane strain and - c E for plane stress - Re{} real part of - u, v components of displacement vector - T temperature - z complex variable (x+i y) - coefficient of thermal expansion - complex variable in a mapped plane - boundary value ofz or - Kolosoffs constant which takes values =3–4 for plane strain and =(3–)/(1+) for plane stress - shear modulus of elasticity - Poissons ratio - _xx,_yy,_xy components of stress tensor - () mapping function     

Longitudinal dielectric function and collective surface oscillations in superconductors

The electrodynamic approach to the problem of collective oscillations in superconductors is considered. The kinetic equation for quasiparticles is used to find the longitudinal dielectric function ₁ (, k) of a pure superconductor at ( is the collision frequency). With the help of the evaluated ₁ (, k) the existence of collective oscillations localized near the boundary of the superconductor is investigated.     

Variational method for measuring dielectric parameters of polar liquids at ultrahigh frequencies

Conclusions Owing to the use of nomograms the above method is universal and rapid. It is independent of the frequency at which the values of and are measured, and it is equally applicable for measuring dielectric parameters of polar liquids which are highly absorbent at ultrahigh frequencies and have one or two clearly expressed minima in the relationship of tol, and for liquids with low dielectric losses in the uhf range, whose measurement with adequate precision is difficult by other methods. Among the deficiencies of the suggested method one should note the two values obtained for _d and tan /2 from the nomogram readings. However, this deficiency can easlly eliminated either by comparing the two values for _d and tan /2 with those obtained for them from a similar nomogram and the second minimum in the relationship of tol, or by an approximate evaluation of _d and tan /2 by means of any other less precise measuring method.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 48–49, October, 1970.