Yuxian Liu

Properties of Hirsch-type indices: the case of library classification categories

We present an application of the h-index in a context which does not include publications or citations. Rankings of library classification categories using the h-, g-and R-index are shown to be statistically equivalent. Moreover these indices seem to have the same discriminating power, as measured by the Gini concentration index. We further present best fitting Zipf-Mandelbrot functions for the h-distributions of classifications in different libraries.

A framework for knowledge integration and diffusion

Purpose – This paper aims to introduce a general framework for the analysis of knowledge integration and diffusion using bibliometric data.Design/methodology/approach – The authors propose that in order to characterise knowledge integration and diffusion of a given issue (the source, for example articles on a topic or by an organisation, etc.), one has to choose a set of elements from the source (the intermediary set, for example references, keywords, etc.). This set can then be classified into categories (cats), thus making it possible to investigate its diversity. The set can also be characterised according to the coherence of a network associated to it.Findings – This framework allows a methodology to be developed to assess knowledge integration and diffusion. Such methodologies can be useful for a number of science policy issues, including the assessment of interdisciplinarity in research and dynamics of research networks.Originality/value – The main contribution of this article is to provide a simple...

Definitions of time series in citation analysis with special attention to the h-index

The structure of different types of time series in citation analysis is revealed, using an adapted form of the Frandsen–Rousseau notation. Special cases where this approach can be used include time series of impact factors and time series of h-indices, or h-type indices. This leads to a tool describing dynamic aspects of citation analysis. Time series of h-indices are calculated in some specific models.

A layered framework to study collaboration as a form of knowledge sharing and diffusion

Collaboration can be described using layered systems such as the article–author–institute–country structure. These structures can be considered ‘cascades’ or ‘chains’ of bipartite networks. We introduce a framework for characterizing and studying the intensity of collaboration between entities at a given level (e.g., between institutions). Specifically, we define the notions of significant, essential and vital nodes, and significant, essential and vital sub paths to describe the spread of knowledge through collaboration in such systems. Based on these notions, we introduce relative and absolute proper essential node (PEN) centrality as indicators of a nodes importance for diffusion of knowledge through collaboration.

Towards a representation of diffusion and interaction of scientific ideas: The case of fiber optics communication

The research question studied in this contribution is how to find an adequate representation to describe the diffusion of scientific ideas over time. We claim that citation data, at least of articles that act as concept symbols, can be considered to contain this information. As a case study we show how the founding article by Nobel Prize winner Kao illustrates the evolution of the field of fiber optics communication. We use a continuous description of discrete citation data in order to accentuate turning points and breakthroughs in the history of this field. Applying the principles explained in this contribution informetrics may reveal the trajectories along which science is developing.

Empirical series of journal h-indices: The JCR category Horticulture as a case study

AbstractTwo types of series of h-indices for journals published in the field of Horticulture during the period 1998–2007 are calculated. Type I h-indices are based on yearly data, while type II h-indices use cumulative data. These h-indices are also considered in a form normalised with respect to the number of published articles.It is observed that type I h-indices, normalised or not, decrease linearly over a period of ten years. The type II series, however, is not linear in nature: it exhibits partly a concave shape. This proves that the journals (in Horticulture) do not exhibit a linear increase in h-index as argued by Hirsch in the case of life-time achievements of scientists.In the second part of the paper, an attempt is made to study the relative visibility of a journal and its change over time, based on h-indices of journals. It is shown that: the h-index over the complete period 1998–2007 of the journal Theoretical & Applied Genetics (h = 62) is much higher than that of all other journals in the fieldthe relation between the number of publications and the type II h-index for the whole period is not an exact power law (as it would have to be if the Egghe-Rousseau model were applicable)in order to study the dynamic aspects of journal visibility, a field-relative normalised h-ratio is defined to monitor systematic changes in the field of Horticulture. Except for two journals, the Pearson correlation coefficient for yearly values of this field-relative normalised h-ratio indicates that there is no systematic change of the performance of the journals with respect to the field as a whole.

Citation analysis and the development of science: A case study using articles by some Nobel prize winners

Using citation data of articles written by some Nobel Prize winners in physics, we show that concave, convex, and straight curves represent different types of interactions between old ideas and new insights. These cases illustrate different diffusion characteristics of academic knowledge, depending on the nature of the knowledge in the new publications. This work adds to the study of the development of science and links this development to citation analysis.

Interestingness and the essence of citation

Purpose – This paper aims to provide a new insight into the reasons why authors cite.Design/methodology/approach – The authors argue that, based on philosophical ideas about the essence of things, pure rational thinking about the role of citations leads to the answer.Findings – Citations originate from the interestingness of the investigated phenomenon. The essence of citation lies in the interaction between different ideas or perspectives on a phenomenon addressed in the citing as well as in the cited articles.Research limitations/implications – The findings only apply to ethical (not whimsical or self‐serving) citations. As such citations reflect interactions of scientific ideas, they can reveal the evolution of science, revive the cognitive process of an investigated scientific phenomenon and reveal political and economic factors influencing the development of science.Originality/value – This article is the first to propose interestingness and the interaction of ideas as the basic reason for citing. Th...

A preliminary investigation on diffusion through a layered system

We introduce layered systems such as the citations–citing authors–citing institutes–citing countries one. Diffusion of scientific ideas flows through such layered systems. Our contribution contains three main topics: a fractional counting system for the number of different units in a layer; the fractional number of items of the same type, i.e. in the same layer, over which ideas have been diffused; and the evenness of diffusion over different layers. In this way we construct a coherent system to measure the extent to which scientific ideas are diffused.

Mathematical properties of Q-measures

Q-measures are network indicators that gauge a nodes brokerage role between different groups in the network. Previous studies have focused on their definition for different network types and their practical application. Little attention has, however, been paid to their theoretical and mathematical characterization. In this article we contribute to a better understanding of Q-measures by studying some of their mathematical properties in the context of unweighted, undirected networks. An external Q-measure complementing the previously defined local and global Q-measure is introduced. We prove a number of relations between the values of the global, the local and the external Q-measure and betweenness centrality, and show how the global Q-measure can be rewritten as a convex decomposition of the local and external Q-measures. Furthermore, we formally characterize when Q-measures obtain their maximal value. It turns out that this is only possible in a limited number of very specific circumstances.