Semantic word shifts in a scientific domain

Understanding semantic word shifts in scientific domains is essential for facilitating interdisciplinary communication. Using a data set of published papers in the field of information retrieval (IR), this paper studies the semantic shifts of words in IR based on mining per-word topic distribution over time. We propose that semantic word shifts not only occur over time, but also over topics. The shifts are examined from two perspectives, the topic-level and the context-level. According to the over-time word-topic distribution, stable words and unstable words are recognized. The diverging and converging trends in the unstable type reveal characteristics of the topic evolution process. The context-level shifts are further detected by similarities between word vectors. Our work associates semantic word shifts with the evolving of topics, which facilitates a better understanding of semantic word shifts from both topics and contexts.     

The measurement of a country's scientific and technological potential

The paper suggests a formula for the measurement of the national science and technology potential. This is based on a decision-making framework for the development of indicators for theS & T system.     

Solution of a Dirichlet problem in a crescent-shaped domain

We present a solution of a Dirichlet problem for the Laplace equation in a crescentshaped domain and apply this solution to some stationary problems of heat conduction, electrostatics, and the theory of elasticity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 6, pp. 1024–1031, June, 1986.     

Dynamics of a scientific field analysed by co-subfield structures

This paper discusses the possibility to represent scientific development by second-order networks in different modalities. In particular, a specific modality structured by subfield-to-subfield relations is presented. By constructing such co-subfield maps for successive periods of time, we were able to describe the changing subfield relations within the field of chemical engineering. In this way, dynamical processes in the development of a field as a whole can be revealed. Advantages and disavantages as compared to co-citation and co-word mapping techniques are discussed and the importance of developing combined techniques is stressed.     

The growth striations and ferroelectric domain structures in Czochralski-grown LiNbO3 single crystals

The rotational striations and power striations are studied in LiNbO₃ crystals and one-to-one correspondence between the striations and temperature fluctuations is demonstrated. The ferroelectric domain structures related to the rotational striations and the power striations have been observed. The distribution of solute concentration in rotational striations is measured by means of energy dispersive X-ray analysis in the scanning electron microscope, and it has been concluded that the ferroelectric domain structures depend on the solute concentration gradient.     

Symmetric and asymmetric domain structures in a semi-infinite single crystal

The distribution of magnetization in a semi-infinite single crystal of square cross section has been determined by means of micromagnetic modeling. It is established that both symmetric and asymmetric stable domain structures exist in the system in a broad range of variation of the magnetic anisotropy.     

The measurement of international scientific collaboration

A growing science policy interest in international scientific collaboration has brought about a multitude of studies which attempt to measure the extent of international scientific collaboration between countries and to explore intercountry collaborative networks. This paper attempts to clarify the methodology that is being used or can be used for this purpose and discusses the adequacy of the methods. The paper concludes that, in an analysis of collaborative links, it is essential to use both absolute and relative measures. The latter normalize differences in country size. Each yields a different type of information. Absolute measures yield an answer to questions such as which countries are central in the international network of science, whether collaborative links reveal a centre — periphery relationship, and which countries are the most important collaborative partners of another country. Relative measures provide answers to questions of the intensity of collaborative links.     

Inverse boundary-value problem of heat conduction for a two-dimensional domain

An approximate solution of a two-dimensional inverse problem is constructed on the basis of a solution of the Cauchy problem obtained in the form of a series in the derivatives and the Tikhonov regularization method.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 40, No. 2, pp. 352–358, February, 1981.     

Modelling the growth of papers in a scientific specialty

A growth model of the journal literature is proposed and applied to the growth of the literature of theoretical population genetics (1850–1980).     

Optimal growth windows of multiferroic BiFeO3 films and characteristics of ferroelectric domain structures

Multiferroic BiFeO₃ films of smooth surface and fully-saturated ferroelectric hysteresis loops have been grown by RF magnetron sputtering. The (001)-oriented epitaxial films showed a large remanent polarisation of 61 µC/cm². A strategy to grow BiFeO₃ films of good ferroelectric property was demonstrated, that was using fast growth rate to achieve accurate stoichiometry for the BiFeO₃ phase and at the same time to avoid the formation of impurity phases associated with the fast growth by accurate control of thermodynamic parameters such as oxygen partial pressure and temperature, as well as proper selection of substrates. Piezoresponse force microscopy revealed fine spontaneous domains for highly resistive epitaxial films, which were switchable under DC biases. For the polycrystalline films of increased density of free carriers, single-domain grains of about 200 nm in diameter were observed due to effective compensation of depolarisation field by free carriers and therefore allowing larger domains.     

On a numerical solution of the plastic buckling problem of structures

An automated digital computer procedure is presented for the accurate and efficient solution of the plastic buckling problem of structures. This is achieved by a Sturm sequence method employing a bisection strategy, which eliminates the need for having to solve the buckling eigenvalue problem at each incremental (decremental) loading stage that is associated with the usual solution techniques. The plastic bucking mode shape is determined by a simple inverse iteration process, once the buckling load has been established. Numerical results are presented for plate problems with various edge conditions. The resulting computer program written in FORTRAN for the JPL UNIVAC 1108 machine proves to be most economical in comparison with other existing methods of such analysis.     

Pure magnetooptic diffraction and Kerr microscopy of periodic domain structures

The fabrication of a periodic domain structure in a ferromagnetic thin film is reported. This periodic domain structure is formed in a thin continuous magnetic film by coupling it to a periodic array of magnetic elements grown on top. When the array and the continuous film are exchange decoupled, magnetostatic interactions produce in the continuous layer a domain structure replica of the topographic pattern at selected field values. The present work reports a direct confirmation of this periodic domain structure in the flat continuous film by Kerr microscopy, which is responsible for the pure magnetooptic diffraction. The effect on the magnetization processes of oneand two-dimensional structures with different periodicities and dimensions is studied in detail and compared with micromagnetic simulations, for Co and Fe films.     

Inclusion problem of a two-dimensional finite domain: The shape effect of matrix

With the advance in composite mechanics and micromechanics, there are increasing demands for analytical solutions of inclusion problems in a bounded domain. To echo this need, this study is focused on establishing explicit expressions of elastic fields for a 2D elastic domain containing a circular inclusion at center. Unlike the configuration in the classical Eshelby formulation, the elastic domain in this study is bounded and has shapes other than a circle. To circumvent the mathematical difficulty in solving Green’s function in a finite domain, an approach powered by complex potential method, which has been successfully employed to formulate the elastic fields for inclusion problems where matrix is unbounded or bounded by a circle, is extended to finite domains displaying complicated shapes, particularly, a Pascal’s limaçon and a curved square (an approximation of perfect square) in this study. In order to take advantage of the mathematical simplicity inherent in expressing a circular geometry, conformal mapping is used to transform the complex geometry of the finite domain of interest to a unit circle. The governing complex potentials, which capture the discontinuity on the inclusion–matrix interface due to the uniform eigenstrain within the inclusion, are formulated with the aid of Cauchy integral and then explicitly identified by satisfying the prescribed boundary conditions. In this study, the displacement fields for finite domains bounded by a Pascal’s limaçon and a curved square are obtained based on Dirichlet (displacement) boundary conditions imposed by the far field strain. In addition to asymptotical behaviors, firm agreement is also achieved when the analytical solutions based on complex potentials are compared with the FEM results. Furthermore, inverse of the conformal mapping is discussed here in order to get the explicit expression for elastic fields.     

A century of scientific publication: towards a theorization of growth behavior and research-orientation

Scientometrics - This paper attempts to provide an overview of scientific publication trends over the period of a century (1900–2017). It then drills down to three important explorations that...     

Knowledge production and the structure of collaboration networks in two scientific fields

In this paper the relationship between knowledge production and the structure of research networks in two scientific fields is assessed. We investigate whether knowledge production corresponds positively or negatively with different types of social network structure. We show that academic fields generate knowledge in different ways and that within the fields, different types of networks act as a stimulant for knowledge generation.     

A circular inclusion in a finite domain I. The Dirichlet-Eshelby problem

Summary This is the first paper in a series concerned with the precise characterization of the elastic fields due to inclusions embedded in a finite elastic medium. A novel solution procedure has been developed to systematically solve a type of Fredholm integral equations based on symmetry, self-similarity, and invariant group arguments. In this paper, we consider a two-dimensional (2D) circular inclusion within a finite, circular representative volume element (RVE). The RVE is considered isotropic, linear elastic and is subjected to a displacement (Dirichlet) boundary condition. Starting from the 2D plane strain Navier equation and by using our new solution technique, we obtain the exact disturbance displacement and strain fields due to a prescribed constant eigenstrain field within the inclusion. The solution is characterized by the so-called Dirichlet-Eshelby tensor, which is provided in closed form for both the exterior and interior region of the inclusion. Some immediate applications of the Dirichlet-Eshelby tensor are discussed briefly.