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1 – 10 of 932The expression ‘half‐life’, borrowed from physics, has appeared quite frequently in the literature on documentation since 1960, when an article by Burton and Kebler on The…
Abstract
The expression ‘half‐life’, borrowed from physics, has appeared quite frequently in the literature on documentation since 1960, when an article by Burton and Kebler on The ‘half‐life’ of some scientific and technical literatures was published, although it had certainly been used previously. Burton and Kebler point out that literature becomes obsolescent rather than disintegrating (as in its original meaning), so that ‘half‐life’ means ‘half the active life’, and this is commonly understood as meaning the time during which one‐half of the currently active literature was published. Numerous studies have been carried out, mainly by the analysis of citations, to establish obsolescence rates of the literature of different subjects. Bourne points out that different studies have given widely different results, so that many of the ‘half‐life’ figures reported are not valid beyond the particular sample of literature or users surveyed; certainly they cannot be used as accurate measures for discriminating between different subject‐fields.
Mousumi Karmakar, Vivek Kumar Singh and Sumit Kumar Banshal
This paper aims to explore the impact of the data observation period on the computation of altmetric measures like velocity index (VI) and half-life. Furthermore, it also attempts…
Abstract
Purpose
This paper aims to explore the impact of the data observation period on the computation of altmetric measures like velocity index (VI) and half-life. Furthermore, it also attempts to determine whether article-level computations are better than computations on the whole of the data for computing such measures.
Design/methodology/approach
The complete publication records for the year 2016 indexed in Web of Science and their altmetric data (original tweets) obtained from PlumX are obtained and analysed. The creation date of articles is taken from Crossref. Two time-dependent variables, namely, half-life and VI are computed. The altmetric measures are computed for all articles at different observation points, and by using whole group as well as article-level averaging.
Findings
The results show that use of longer observation period significantly changes the values of different altmetric measures computed. Furthermore, use of article-level delineation is advocated for computing different measures for a more accurate representation of the true values for the article distribution.
Research limitations/implications
The analytical results show that using different observation periods change the measured values of the time-related altmetric measures. It is suggested that longer observation period should be used for appropriate measurement of altmetric measures. Furthermore, the use of article-level delineation for computing the measures is advocated as a more accurate method to capture the true values of such measures.
Practical implications
The research work suggests that altmetric mentions accrue for a longer period than the commonly believed short life span and therefore the altmetric measurements should not be limited to observation of early accrued data only.
Social implications
The present study indicates that use of altmetric measures for research evaluation or other purposes should be based on data for a longer observation period and article-level delineation may be preferred. It contradicts the common belief that tweet accumulation about scholarly articles decay quickly.
Originality/value
Several studies have shown that altmetric data correlate well with citations and hence early altmetric counts can be used to predict future citations. Inspired by these findings, majority of such monitoring and measuring exercises have focused mainly on capturing immediate altmetric event data for articles just after the publication of the paper. This paper demonstrates the impact of the observation period and article-level aggregation on such computations and suggests to use a longer observation period and article-level delineation. To the best of the authors’ knowledge, this is the first such study of its kind and presents novel findings.
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B.T. Sampath Kumar and K.S. Manoj Kumar
The main purpose of the present study is to examine the availability and persistence of URL citations in two LIS open access journals. It also intended to calculate the half‐life…
Abstract
Purpose
The main purpose of the present study is to examine the availability and persistence of URL citations in two LIS open access journals. It also intended to calculate the half‐life period of URL citations cited in journal articles.
Design/methodology/approach
A total of 2,890 URL citations cited in 689 research articles published in LIS journals spanning a period of 14 years (1996‐2009) were extracted. In order to check the accessibility of URL citations, W3C link checker was used. After the initial check, inactive URL citations were listed. Domains and HTTP errors associated with inactive URL citations were identified for further analysis. The half‐life period was calculated using the formula t(h)=[t ln(0.5)]/[ln W(t)−ln W(0)].
Findings
The research findings indicated that 57.61 percent (397 of 689) of articles have URL citations and percentage of URL citations increased from 5.98 percent in 1996 to 27.79 percent in 2009. It was found that 26.08 percent of all citations were not accessible during the time of testing and the majority of errors were due to HTTP 404 error code (not found). The domains.net and.gov were more stable compared to the domains.com/.co,.org, and.edu. The half‐life was computed to be approximately 11.5 years, which compares favorably against earlier research works.
Originality/value
This is a comprehensive study on the availability and persistence of URL citations cited in LIS journals articles spanning a period of 14 years. The findings of the study will be helpful to authors, publishers and editorial staff to improve existing URL citation conventions and to promote URL use to ensure that URL citations are accessible in future.
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Symbols for concepts like ‘half life’, ‘impact factor’, ‘normalised impact factor’ and ‘immediacy index’ are proposed and formulas for the determination of their values are…
Abstract
Symbols for concepts like ‘half life’, ‘impact factor’, ‘normalised impact factor’ and ‘immediacy index’ are proposed and formulas for the determination of their values are provided. The features of the concepts are also highlighted.
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Mariam Jalalifard, Yaghoub Norouzi and Alireza Isfandyari‐Moghaddam
The aim of this study is to compare the situation of internet resource citations in scientific articles of the journals of Shahid Beheshti University of Medical Sciences from…
Abstract
Purpose
The aim of this study is to compare the situation of internet resource citations in scientific articles of the journals of Shahid Beheshti University of Medical Sciences from 2005‐2009.
Design/methodology/approach
The research method is an analytical survey with webometrics and citation analysis. The internet was used as a tool for accessing articles. They are separately analyzed on the basis of journal name and publication year. The analysis is done using MATLAB and Excel software.
Findings
A total of 717 articles from seven journals during five years were reviewed. Of 13,448 citations extracted, 120 internet references were found. The final results indicated that the sum of web citations is less than 1 per cent of total citations and only 52 per cent of internet citations in studied journal articles are available. The average half‐life for the medical journals is estimated to be 1.02 years.
Practical implications
To increase the rate of URLs availability, publishers should oblige authors to utilize online archives such as WebCite to preserve expected information for all of the citations referred to in their articles.
Originality/value
This research would be valuable since it is the first that studies stability and persistence of URL domains of medical journals published in Shahid Beheshti University of Medical Sciences according to type of domain names and file extensions. Moreover, this is the first time that the half‐life for medical universities web citations is calculated.
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Yanhui Song, Xukang Shen and Junping Qiu
Aging research has traditionally been an important research topic in the field of Library and Information Science(LIS). The study of aging enables us to grasp the extent of…
Abstract
Purpose
Aging research has traditionally been an important research topic in the field of Library and Information Science(LIS). The study of aging enables us to grasp the extent of development and the status of aging in LIS. The purpose of this paper is to explore the current law of aging in LIS and to research the impact of interdisciplinary citations on the aging of the discipline.
Design/methodology/approach
By using citation analysis methods and fitting them using the Barnett aging model, the aging law of LIS is explored with the help of aging indicators such as citing half-life and Price Index. For interdisciplinary study, the authors explore the pattern of interdisciplinary citations distribution by distinguishing LIS and non-LIS citations by journal name.
Findings
The results show that LIS is currently aging slowly and has reached a relatively mature stage. It has a high reliance on archival literature. The interdisciplinary citations distribution is broadly consistent with the overall citation distribution, and interdisciplinary citations can increase the age of applicability of the literature.
Originality/value
Based on LIS journal citation data, the paper validates the rationality of Barnett model applied in the field of literature aging research using nonlinear regression analysis, which can effectively reflect the aging law of literature and enable scholars to predict its development trend more accurately. In addition, according to the current trend of interdisciplinary citation, this paper explores the impact of interdisciplinary citations on the aging of the literature and provides a new idea for future aging research.
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S.V. Lee, A.N. Hadi, Z.H.Z. Zainal Abidin, N.A. Mazni, N.A. Halim, R. Usop, H.C. Hassan, S.R. Majid and A.K. Arof
The purpose of this paper is to observe the colour and thermal stability of natural red dye consisting of anthocyanin with addition of different aqueous acids and applied as…
Abstract
Purpose
The purpose of this paper is to observe the colour and thermal stability of natural red dye consisting of anthocyanin with addition of different aqueous acids and applied as coating films.
Design/methodology/approach
The natural red dye was extracted from Hibiscus sabdariffa L. (roselle) flowers and mixed with 1 per cent hydrochloric acid, 5 per cent acetic acid, 5 per cent citric acid and 5 per cent oxalic acid. All the dye samples were exposed to heat and UV-B to observe the colour stability by calculating the half-life and rate of reaction. In coating film application, each of the dye samples was mixed with 25 wt% of poly(vinyl alcohol) (PVA) and applied on to a glass substrate. The coating samples’ colour stability was observed by using CIE L*a*b* colour space coordinates. The coating films’ weight loss stability against temperature was observed by using thermogravimetric analysis.
Findings
Addition of hydrochloric acid enhances the thermal and UV stability of the anthocyanin natural dye. This can be observed from the calculation of the half-life of the dye. The half-life values for the thermal and UV stability studies were 1,155 hours and 210 hours, respectively. In coating films, the sample with addition of acetic acid showed the highest colour stability with colour difference (ΔE*) value 8.95.
Research limitations/implications
The coating films developed in this work are not suitable to be applied on metal substrates due to the presence of water, which can contribute to the corrosion formation.
Practical implications
The coating films developed in this work are suitable for washable coating application. In other words, they are non-permanent coatings applied on a glass substrate.
Originality/value
Development of water-based coatings from PVA binder with anthocyanin colourant is introduced in this study.
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Terminology and parameters for describing the relation between figures for the use of library literature and for its age are discussed. Unless a correction for growth is applied…
Abstract
Terminology and parameters for describing the relation between figures for the use of library literature and for its age are discussed. Unless a correction for growth is applied, half‐life fails a simple test of suitability, as do Brookes's ageing and utility factors. Results based on cumulated data have other important disadvantages. Relative ‘use‐per‐item’ figures are satisfactory. The need to relate terminology more closely to the facts they represent is stressed: item‐consultation decay rate, and 50% consultation probability age are suggested and defined. In the context of citation studies, item‐citation decay rate and 50% citation probability age are equivalent and avoid similar objections. In data from NRLSI, item‐consultation decay rates are only approximately exponential. Different rates are demonstrated for updating and basic searches, for academic and other types of readers, and for types of literature. For some historical searches negative decay rates were found in the NRLSI and BML.
Hanna Lo, Alireza Ghasemi, Claver Diallo and John Newhook
Condition-based maintenance (CBM) has become a central maintenance approach because it performs more efficient diagnoses and prognoses based on equipment health condition compared…
Abstract
Purpose
Condition-based maintenance (CBM) has become a central maintenance approach because it performs more efficient diagnoses and prognoses based on equipment health condition compared to time-based methods. CBM models greatly inform maintenance decisions. This research examines three CBM fault prognostics models: logical analysis of data (LAD), artificial neural networks (ANNs) and proportional hazard models (PHM). A methodology, which involves data pre-processing, formulating the models and analyzing model outputs, is developed to apply and compare these models. The methodology is applied on NASA’s Turbofan Engine Degradation data set and the structural health monitoring (SHM) data set from a Nova Scotia Bridge. Results are evaluated using three metrics: error, half-life error and a cost score. This paper concludes that the LAD and feedforward ANN models compares favorably to the PHM model. However, the feedback ANN does not compare favorably, and its predictions show much larger variance than the predictions from the other three methods. Based on these conclusions, the purpose of this paper is to provide recommendations on the appropriate situations in which to apply these three prognostics models.
Design/methodology/approach
LAD, ANNs and PHM methods are adopted to perform prognostics and to calculate the mean residual life (MRL) of eqipment using NASA’s Turbofan Engine Degradation data set and the SHM data set from a Nova Scotia Bridge. Statistical testing was used to evaluate the statistical differences between the approaches based on these metrics. By considering the differences in these metrics between the models, it was possible to draw conclusions about how the models perform in specific cases.
Findings
Results were evaluated using three metrics: error, half-life error and a cost score. It was concluded that the LAD and feedforward ANN models compares favorably to the PHM model. However, the feedback ANN does not compare favorably and its predictions show much larger variance than the predictions from the other three methods. Overall the models predict failure after it has already occurred (negative error) when the residual life is large and vice versa.
Practical implications
It was concluded that a good CBM prognostics model for practical implications can be determined based on three main considerations: accuracy, run time and data type. When accuracy is a main concern, as in the case where impacts of failure are large, LAD and feedforward neural network are preferred. The preference changes when run time is considered. If data can be easily collected and updating the model is performed often, the ANNs and LAD are preferred. On the other hand, if CM data are not easily obtainable and existing data are not representative of the population’s behavior, data type comes into play. In this case, PHM is preferred.
Originality/value
Previous research in the literature performed reviews of multiple independent studies on CBM techniques performed on different data sets. They concluded that it is typically harder to implement artificial intelligence models, because of difficulties in data procurement, but these approaches offer improved performance as compared to more traditional model-based and statistical approaches. In this research, the authors further investigate and compare the performance and results from two major artificial intelligence models, namely, ANNs and LAD, and one pioneer statistical model, PHM over the same two real life prognostics data sets. Such in-depth comparison and review of major CBM techniques was missing in current literature of CBM field.
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The aim of this chapter is to explore whether price dynamics is homogenous across Emerging Europe. We employ dynamic panel estimation techniques (including the Pooled Mean Group…
Abstract
The aim of this chapter is to explore whether price dynamics is homogenous across Emerging Europe. We employ dynamic panel estimation techniques (including the Pooled Mean Group estimator of Pesaran, Smith, and Shin) over the 2003–2013 period and use Germany, and respectively, the European Union (EU) as the references. Results highlight some heterogeneity across the Emerging Europe members in terms of price convergence speed. Findings are robust across different specifications.
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