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.     

The role of trade literature in the communication system

Bibliometric methods in general undervalue technological research. This study examines the relation in literature between technological/industrial journals and scientific journals in the case of the plastics industry and polymer science. Trade-journals cannot be used in a straightforward bibliometric manner, but can be an aid in mapping the different groups and reveal the hidden communication between technological and scientific communities.     

Study of thermal and gasdynamic characteristics of a subsonic plasma air jet

Results are presented from a numerical analysis and experimental study of the enthalpy and velocity distributions along and across a subsonic plasma air jet.Notation x, r axial and radial coordinates - u, v axial and radial components of velocity - density - viscosity - emissivity - r_0.5 radius at which local value of velocity or enthalpy is half its axial value - , radii of dynamic and thermal boundary layers - q heat flux, kW/m² - h, h_w stagnation enthalpy and enthalpy at wall temperature, kJ/kg - p, p stagnation pressure and static pressure, Pa - R radius of curvature of spherical front part of body Indices 0 teconditions at nozzle edge - m conditions on jet axis - conditions on outer boundary of jet Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 1, pp. 34–39, January, 1982.     

Differences in the construction of sci based bibliometric indicators among various producers: A first over view

This contribution discusses basic technical-methodological issues with respect to data collection and the construction of bibliometric indicators, particularly at the macro or meso level. It focusses on the use of the Science Citation Index. Its aim is to highlight important decisions that have to be made in the process of data collection and the construction of bibliometric indicators. It illustrates differences in the methodologies applied by several important producers of bibliometric indicators: the Institute for Scientific Information (ISI); CHI Research, Inc.; the Information Science and Scientometrics Research Unit (ISSRU) at Budapest; and the Centre for Science and Technology Studies at Leiden University (CWTS). The observations made in this paper illustrate the complexity of the process of standardisation of bibliometric indicators. Moreover, they provide possible explanations for divergence of results obtained in different studies. The paper concludes with a few general comments related to the need of standardisation in the field of bibliometrics.     

On intrinsic and extrinsic effects in the surface impedance of cuprate superconductors

Surface impedance measurements in the normal and superconducting state are an excellent method to study conduction electron dynamics and extended defects. Electron dynamics show up most clearly in the relaxation range, i.e., for distances traveled in one rf periods= _F/ ( _F Fermi velocity) being smaller or of the order of the penetration depth and mean free pathl. For materials with _F10⁷ cm/sec the relaxation range is easily accessible forf0.1 THz. Then, in the normal state, relaxation defines the surface impedance with an intrinsic penetration depth _I approaching the London penetration depth _L andR _{I 0 L}/ 2 as surface resistance, allowing measurement of _L and relaxation time(T, ). In the superconducting state the photon interaction scales with _L/ _L=1/( _F dimension of Cooper pairs forl) and causes at low frequencies an absorption rate growing with, which is decreasing with _F/l. The rate increase proportional to turns to a decrease above 0.1 THz, which is accompanied by a decrease ofA with frequency which is stronger for large and small _F/l. These characteristic dependences allow measurement of material parameters, anisotropy, and dynamics of electrons, especially the relaxation rate. But presently, the rf surface impedanceZ is still shrinking with material improvements, which shows, clearly, that theZ=Z _I+Z _res is still dominated by extrinsic properties summarized inZ _res. We present evidence thatZ _res is due to the large leakage currentj _bl and the smallj _cJ of weak links where the latter destroys the intrinsic shielding from a _I-thin seam _J deep into the bulk. This causes rf residual lossesR _res( ₀)² _J ³ _bl/2.R _res stays finite atT-0 due to _bl(T0) _bl(j _bl) being amplified by ( _J/ _I)³>10³ as a weighting factor. The appropriate measure of weak links are the grain-boundary resistanceR _bn((0)) enhancing _JR _bn andR _resR _bn ² . Thus,Z _res is minimal for minimal extrapolated resistivity(T0).To identify the weak links as a new entity, the H-field dependence is most helpful, because at very low fieldsH _c 1J1/ _J Josephson fluxons penetrate into the weak links. These Josephson fluxons show negligible flux flow or flux creep, and enhanceZ _res by _J(H, T) . The measuredj _cJ(H, T) andj _bl values explainZ _res quantitatively as well as in temperature (a+T ⁿ ) (n1,T<T _c /2) and in field (b+H ⁿ ) (n1,H>H _c1J) dependence. The strength of the field dependencedZ _res/dHZ _res(H _c1J )/H _c2J(T) is not only a measure ofZ _res andH _c2J(T) but is crucial for nonlinear effects and (fluxon) noise also, which limit the performance of rf devices.     

Co-word maps of biotechnology: An example of cognitive scientometrics

To analyse developments of scientific fields, scientometrics provides useful tools, provided one is prepared to take the content of scientific articles into account. Such cognitive scientometrics is illustrated by using as data a ten-year period of articles from a biotechnology core journal. After coding with key-words, the relations between articles are brought out by co-word analysis. Maps of the field are given, showing connections between areas and their change over time, and with respect to the institutions in which research is performed. In addition, other approaches are explored, including an indicator of theoretical level of bodies of articles.     

Kinetics of the α → γ phase transformation in LiAlO2 under various atmospheres within the 1073–1173 K temperatures range

Stability of the LiAlO₂ crystallographic forms within given temperature limits, especially the occurrence of -LiAlO₂ phase transformation, is one of the crucial problems of application of this compound as solid phase matrix for electrolyte in molten carbonate fuel cells (MCFC). In this study, kinetics of this transformation has been investigated under atmospheres of CO₂ and N₂, both dehydrated and water vapor containing, at constant temperatures 1073, 1123 and 1173 K, in the -LiAlO₂ powder prepared in a molten salts ambience. The increasing -LiAlO₂ phase concentration in the -LiAlO₂ sample was determined by X-ray diffractometry as dependent on time of heating the sample. Similar measurements have been performed with -LiAlO₂ samples after 5 h of heating at temperatures within 923–1223 K. The results of this investigation suggest the existence of some chemical steps of the overall phase transformation process, probably the decomposition of the double lithium-aluminum oxide at the -LiAlO₂ particle surfaces via a surface-nucleation mechanism. This step determines the overall transformation rate, strongly depending on gas atmosphere and on molten carbonate ambience (solution-deposition mechanism). This transformation does not take place below 973 K, which is the upper temperature limit of the MCFC operation.     

Bibliometric cartography of scientific and technological developments of an R & D field

This paper presents the results of an exploration of bibliometric mapping as an analytic tool to study the important aspects of the relation between science and technology, in particular the science base of technology. We discuss a bibliometric (in particular a publication- and patent-based) approach to develop a cartography of science and technology, i.e., the construction of geometrically organized maps in order to visualize the changing internal structure of science and technology. These maps are based on co-occurrences of publication and patent keywords. We focus on a specific R & D field: optomechatronics. This field is characterized by a strong knowledge transfer between science and technology. We constructed maps for both the science as well as the technology side. Comparison of these two allows the exploration of existing or possible interaction of scientific and technological developments. We identified related subfields (co-word clusters) in the maps of both sides in order to illustrate the interaction between science and technology. Subsequently, we extended the information given by the maps with information on the role and position of a number of countries in the different subfields of optomechatronics, both at the science side as well as at the technology side. This is done by identification of actors in the subfields represented by word clusters in the maps. Cartography of science and technology allows the observation of the structure (and its changes) of scientific and technology fields. Moreover, it illustrates both existing as well as possible links between science and technology. It therefore presents a powerful tool for science, technology and R & D policy.Paper presented at the Fourth International Conference on Bibliometrics, Informetrics and Scientometrics in Berlin (Germany), September 11–15, 1993.     

Low-Mach-Number Asymptotics of the Navier-Stokes Equations

A multiple-time scale, single-space scale asymptotic analysis of the compressible Navier-Stokes equations reveals how the heat-release rate and heat conduction affect the zeroth-order global thermodynamic pressure, the divergence of velocity and the material change of density at low-Mach-numbers. The asymptotic analysis identifies the acoustic time change of the heat-release rate as the dominant source of sound in low-Mach-number flow. The viscous and buoyancy forces enter the computation of the second-order incompressible pressure in low-Mach-number flow in a similar way as they enter the pressure computation in incompressible flow, except for a nonzero velocity-divergence constraint. If the flow equations are averaged over an acoustic wave period, the averaged velocity tensor describes the net acoustic effect on the averaged flow field. Removing acoustics from the equations altogether leads to the low-Mach-number equations, which allow for large temperature and density changes as opposed to the Boussinesq equations.     

A scientometric cognitive study of neural network research: Expert mental maps versus bibliometric maps

This paper reports on a quantitative analytical methodology which deals with perceptions of scientific experts regarding the intellectual shape and contents (cognitive structure) of their scientific domain. This study examines the method's utility for studying expert views in general, and, more specifically, its strengths and weaknesses as a tool for improving validation studies of bibliometric maps involving subject experts. The main premise is that expert views are based on their internal knowledge structures (mental schemes) of which relevant features can be captured in quantitative data. This approach allows a rigorous and systematic way of studying mental schemes across subject experts. Spatial representations of their data (mental maps) provide insight in properties underlying those knowledge structures. Data from different experts are reconciled to construct a common mental map which displays a group view. This study includes a test to establish the validity of individual mental maps and common mental maps. The methodology is applied to the views of 14 researchers in the field of neural network research and related areas. Key-findings are: (i) mental maps can provide valid representations of expert mental schemes, (ii) experts sharing the same subject field are more likely to share views, (iii) expert judgements of bibliometric maps are affected by the structure of their own mental schemes, as well as (iv) by their views regarding the utility of those maps, and (v) common mental maps and a bibliometric co-word map based on the same set of items differ significantly, showing a resemblance on main features only.     

Mapping co-word structures: A comparison of multidimensional scaling and leximappe

The LEXIMAPPE method and Multidimensional Scaling (MDS) are discussed as methods to visualize (map) characteristics of structures of word-occurrence (co-word) relations. Utilization of MDS is proposed as an alternative mapping method able to circumvent problematic features of LEXIMAPPE maps of the total co-word structure. A comparison of both methods on the same real-life co-word matrix demonstrates topological advantages of an extended MDS-mapping.     

The evaluation of plant biomass research: A case study of the problems inherent in bibliometric indicators

The aim of this project was to evaluate research groups working in the broad field of plant biomass in the areas outside the USA and the EC. The assessment had two key elements: the measurement of scientific productivity and the investigation of factors affecting research performance. Research groups were identified from a range of information sources. Data on funding, information access, staffing, publication policy and degree of awareness of other research groups in the field were collected during the course of interviews. Two approaches —bibliometric analysis and peer review — were examined as a means of constructing indicators for assessing research output.Following a critical review of the use of bibliometric indicators in peripheral countries, the results from a study of eight countries are presented. Neither of two indicators employed proved to be a particularly successful method of evaluating research, and this finding is discussed in relation to publication patterns, the nature of the research community and the research field under study. Finally, the use of a peripatetic expert was found to have some value as a means of assessment.Paper presented at the International Conference on Science Indicators for Developing Countries, Paris, 15–19 October, 1990.     

Peer review and bibliometric indicators of scientific performance: A comparison of cum laude doctorates with ordinary doctorates in physics

Quality judgments of predominantly local senior scientists regarding the scientific performance of candidates for a doctorate degree in physics were compared to the non-local short-term and long-term impact of the work published by these candidates before and after graduation. It was hypothesized that publications of cum laude degree-holders (cumlaudes), both shortly before and shortly after the award of the degree, would be higher cited both on the short and long run than publications of ordinary degree-holders. Before graduation, cumlaudes were significantly more productive, as well as authors of more highly cited publications than ordinary doctorates. Publications authored by cumlaudes some years before their graduation received on the average more than twice as many citations as publications authored by non-cumlaudes. However, in particular for cumlaudes, productivity and impact decreased sharply in years after graduation. After graduation, cumlaudes continued to be more productive than non-cumlaudes, but the impact of their publications equalled those produced by non-cumlaudes. The results offer little evidence for the Matthew effect and the Ortega hypothesis, but support the validity of both peer review outcomes and bibliometric impact assessments of scientific performance.     

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.     

The θ projection method and small creep strain interpolations in a commercial Titanium alloy

The paper describes the early and final uniaxial creep behaviour of a Titanium alloy used for manufacturing intermediate power compressor disks and blades. Tests were conducted at the operating temperature (773 K) for such components and for rupture lives up to 3600 hours. Creep curves were fitted using either the conventional 4 model or the recently developed 6 equation. Parameters allowing the interpolation of times to small strains were produced and their accuracy checked against experimental values using distributions found to be most supported by the data. At strains above 0.75% both methods yielded zero mean interpolation errors. At strains above 0.27% and below 0.75% the 4 equation produced systematic errors in interpolation but the 6 function gave errors which were not statistically different from zero. For strains below 0.27% both techniques produced systematic interpolation errors but the 6 interpolations were always significantly better than their 4 counterparts. Both the 6 and 4 techniques produced systematic errors when predicting the failure time using interpolated rupture strains. Unlike the 4 function, the 6 equation produced unbiased predictions of the minimum creep rate and so produced failure time interpolations from the Monkman–Grant relation that were indistinguishable from zero.     

The use of bibliometric techniques for institutional research evaluation: A study of avian virology research

A bibliometric analysis was made of an area of veterinary research, avian virology, in the context of seeking quantitative indicators to assist research evaluation for the UK Agricultural and Food Research Council (AFRC). In one approach, a list was made of world publications in avian virology using the CAB database which is the most appropriate literature source in terms of subject specificity and breadth of coverage. Means were sought to minimise the labour input required for citation studies of this kind; results based on peak-year citations only were similar to those from the more widely used four-year count, in terms of country-ranking and time trends. In the second method, the publication outputs of several avian virology research groups were assessed in terms of expected citations i.e. the average number of citations per paper received by the journals in which the groups published, as compared to the actual citations received. The rankings of the groups were the same in both methods. This second approach, while giving only approximate citation rates, has the advantage of requiring only in-house data. It seems more appropriate for the ex-post evaluation of the output of research groups in the context of agricultural and food research, and it is suggested that further studies on journal-based indicators are warranted.     

Self-consistent-phonon,random phase,and transfer-integral methods for a linear chain with anharmonic potential

The transfer-integral (TI) method, developed especially for hard-core potentials, is tested with anx ² + ₃x³ + ₄x⁴ potential by a comparison with other methods: In the harmonic approximation the improvement of the TI method over the self-consistent phonon (SCP) method is about as great as that of the SCP method over the random phase approximation (RPA).     

Perspective of webometrics

Since the mid-1990s has emerged a new research field, webometrics, investigating the nature and properties of the Web drawing on modern informetric methodologies. The article attempts to point to selected areas of webometric research that demonstrate interesting progress and space for development as well as to some currently less promising areas. Recent investigations of search engine coverage and performance are reviewed as a frame for selected quality and content analyses. Problems with measuring Web Impact Factors (Web-IF) are discussed. Concluding the article, new directions of webometrics are outlined for performing knowledge discovery and issue tracking on the Web, partly based on bibliometric methodologies used in bibliographic and citation databases. In this framework graph theoretic approaches, including path analysis, transversal links, weak ties and small-world phenomena are integrated.     

Assessing the usefulness of bibliometric indicators for the humanities and the social and beha vioural sciences: A comparative study

An evaluation was made of the use of bibliometric indicators for five disciplines in the humanities (social history, general linguistics, general literature, Dutch literature, and Dutch language) and three disciplines in the social and behavioural sciences (experimental psychology, anthropology, and public administration) in the Netherlands. Articles in journals were the predominant outlet in all disciplines. Monographs and popularizing articles were more important outlets in softer fields than in harder ones. The enlightenment function of scholarship was especially evident in Dutch literature and language, and public administration. Only some of the humanities disciplines are locally oriented. Although many publications were written in English, only experimental psychology, general linguistics, anthropology, and genrral literature were internationally oriented regarding output media. The impact of departments differed greatly both within and between disciplines. For all disciplines, bibliometric indicators are potentially useful for monitoring international impact, as expert interviews confirmed. Especially in Dutch language, Dutch literature and public administration, ISI-citation data are not very useful for monitoring national impact.     

Anisotropic grain growth of R-α-sialon (R = Nd and Er)

Two R--sialon (R_0.6Si_9.3Al_2.7O_0.9N_15.1, R=Nd and Er) compositions were first fired at 1750°C/25 min and 1650°C/2 h respectively for completion of the phase transformation. Elongated -sialon grain morphology was developed in both samples after being re-fired at 1800°C for different periods of time. The growth in width of R--sialon grains is controlled by diffusion in the liquid, while the length growth tends to be interfacial reaction controlled. The anisotropic growth of R--sialon is attributed to the large difference in the growth rate constant between the length and the width directions of the grain.