A Clustering System for Dynamic Data Streams Based on Metaheuristic Optimisation

open access articleThis article presents the Optimised Stream clustering algorithm (OpStream), a novel approach to cluster dynamic data streams. The proposed system displays desirable features, such as a low number of parameters and good scalability capabilities to both high-dimensional data and numbers of clusters in the dataset, and it is based on a hybrid structure using deterministic clustering methods and stochastic optimisation approaches to optimally centre the clusters. Similar to other state-of-the-art methods available in the literature, it uses “microclusters” and other established techniques, such as density based clustering. Unlike other methods, it makes use of metaheuristic optimisation to maximise performances during the initialisation phase, which precedes the classic online phase. Experimental results show that OpStream outperforms the state-of-the-art methods in several cases, and it is always competitive against other comparison algorithms regardless of the chosen optimisation method. Three variants of OpStream, each coming with a different optimisation algorithm, are presented in this study. A thorough sensitive analysis is performed by using the best variant to point out OpStream’s robustness to noise and resiliency to parameter changes

I-Ulysses: A Technical Report

The file attached to this record is the author's final peer reviewed version.The I-Ulysses: Poetry in Motion project is as a virtual reality experience, guiding the user through the unfolding events of James Joyce's Ulysses in real-time. Currently there is a lack of research looking at adapting literature into virtual reality, for the purposes of cultural heritage, or for serious learning. I-Ulysses is aimed at addressing this gap, by providing an educational tool, intended to help the user understand key aspects of the book. What follows is a technical report, outlining the objectives, aims and results of the I-Ulysses project

Propiedades químicas de aceites de oliva virgen de cultivares iraníes de las regiones de Fadak y Gilvan

The aim of this study is to evaluate the chemical compositions (total phenol, fatty acid, sterolic compounds) of Iranian virgin olive oil (Zard, Rowghani, Mari) cultivated in the Gilvan (Zanjan Province) and Fadak (Qom Province) regions. Total phenols were determined using the Folin-Ciocalteu assay. Fatty acid and sterol profiles were also analyzed using gas chromatography. In most cases, significant effects (P < 0.05) of cultivars and locations were detected by the chemical composition of the oil samples. The fatty acid analysis indicated that the Mari variety from Gilvan had high oleic/low linoleic acid content; therefore it is a highly resistant olive oil against oxidation. Furthermore, the high mean values of total sterols were also obtained for the Mari variety. The oil of the Zard variety from Gilvan had the maximum amount of phenols as a positive quality index. Therefore, the Mari variety, especially from Gilvan has been suggested as a superior cultivar compared to the Zard and Rowghani varieties.El objetivo de este estudio fue evaluar la composición química (fenoles totales, ácidos grasos, y esteroles) de aceites de oliva virgen iranies (Zard, Rowghani, Mari) cultivados en las regions de Gilvan (provincia de Zanjan) y Fadak (provincia de Qom). Los fenoles totales se determinaron utilizando el método de Folin-Ciocalteu. Los perfiles de ácidos grasos y de esteroles se determinaron mediante cromatografía de gases. En la mayoría de los casos, existen diferencias significativos de los cultivares y los lugares detectados por la composición química (P < 0,05 ). El análisis de ácidos grasos indicó que la variedad Mari de Gilvan presenta una relación alta oleico/ linoleico; por lo tanto, es un aceite de alta resistencia contra la oxidación. Por otra parte, los valores medios altos de esteroles totales también fueron obtenidos para la variedad Mari. El aceite de la variedad Zard de Gilvan presentó la mayor cantidad de fenoles, considerado este valor como un índice de calidad positivo. La variedad Mari especialmente en Gilvan se sugeriere como un cultivar superior en comparación con las variedades Zard y Rowghani

A T1OWA Fuzzy Linguistic Aggregation Methodology for Searching Feature-based Opinions.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Online services such as Amazon, Tripadvisor, Ebay, etc., allow users to express sentiments about different products or services. Not only that, in some cases it is also possible to express sentiments about the different features characterizing those products or services. Most users express sentiments about individual features by using numerical values, which sometimes do not allow users to reflect properly what they are meaning and therefore they are misleading. To overcome this key issue and make users’ opinions in online services more comprehensive, a new methodology for representing sentiments using linguistic term sets instead of numerical values is presented. In addition, this methodology will allow to implement importance degrees on the different features characterizing users’ opinions. From both sentiments and importance of the features, the most important opinions for each user is derived via an aggregation step based on the Type-1 Ordered Weighted Averaging (T1OWA) operator, which is able to aggregate the corresponding fuzzy set representations of linguistic terms. Furthermore, the final output of the T1OWA based-search process can easily be interpreted by users because it is always of the same type (fuzzy) and defined in the same domain of the original fuzzy linguistic labels. A case study is presented where the T1OWA operator methodology is used to assess different opinions according to different user profiles

Chemical properties of virgin olive oil from Iranian cultivars grown in the Fadak and Gilvan regions

The aim of this study is to evaluate the chemical compositions (total phenol, fatty acid, sterolic compounds) of Iranian virgin olive oil (Zard, Rowghani, Mari) cultivated in the Gilvan (Zanjan Province) and Fadak (Qom Province) regions. Total phenols were determined using the Folin-Ciocalteu assay. Fatty acid and sterol profiles were also analyzed using gas chromatography. In most cases, significant effects (<em>P</em> < 0.05) of cultivars and locations were detected by the chemical composition of the oil samples. The fatty acid analysis indicated that the Mari variety from Gilvan had high oleic/low linoleic acid content; therefore it is a highly resistant olive oil against oxidation. Furthermore, the high mean values of total sterols were also obtained for the Mari variety. The oil of the Zard variety from Gilvan had the maximum amount of phenols as a positive quality index. Therefore, the Mari variety, especially from Gilvan has been suggested as a superior cultivar compared to the Zard and Rowghani varieties.<br><br>El objetivo de este estudio fue evaluar la composición química (fenoles totales, ácidos grasos, y esteroles) de aceites de oliva virgen iranies (Zard, Rowghani, Mari) cultivados en las regions de Gilvan (provincia de Zanjan) y Fadak (provincia de Qom). Los fenoles totales se determinaron utilizando el método de Folin-Ciocalteu. Los perfiles de ácidos grasos y de esteroles se determinaron mediante cromatografía de gases. En la mayoría de los casos, existen diferencias significativos de los cultivares y los lugares detectados por la composición química (P < 0,05 ). El análisis de ácidos grasos indicó que la variedad Mari de Gilvan presenta una relación alta oleico/ linoleico; por lo tanto, es un aceite de alta resistencia contra la oxidación. Por otra parte, los valores medios altos de esteroles totales también fueron obtenidos para la variedad Mari. El aceite de la variedad Zard de Gilvan presentó la mayor cantidad de fenoles, considerado este valor como un índice de calidad positivo. La variedad Mari especialmente en Gilvan se sugeriere como un cultivar superior en comparación con las variedades Zard y Rowghani

The impact of Library and Learning Services on student progression and degree attainment

From the 1960’s onwards UK HE has expanded to include women, those from black and minority ethnic groups and the disabled. However, a degree attainment gap has been identified within these groups1. The degree attainment gap is the difference in the proportion of ‘good’ degrees i.e. first and upper second compared to all other classes awarded. The greatest gap is between white and black and minority ethnic students and half the disparity can be attributed to prior achievement2. Use of academic library resources is associated with continued progression and better academic results3. De Montfort University is the most socially diverse university in the UK4. This provides an opportunity to examine the use of library services by different demographic groups and investigate the impact of such usage on student progression and degree attainment. The Directorate of Library and Learning Services (LLS) provides study resources such as books, journals, e-resources and study support for academic writing, maths, statistics and information literacy and referencing

Short-sale constraints and stock prices: evidence from implementation of securities refinancing mechanism in Chinese stock markets

open access articleQualified Securities for Short-sale Refinancing (QSSR) is a unique trading mechanism that has exogenously increased the supply of loanable securities in Chinese stock markets. Using difference-in-differences (DID) methodology, this paper is the first to investigate whether and to what extent additions to the QSSR eligibility list affect short selling activities and stock price behaviors. The paper finds that stocks added to the QSSR list exhibit better liquidity and less negative skewness in returns than non-QSSR stocks. However, QSSR stocks are more volatile and display a higher frequency of extreme negative returns. In addition, on average, QSSR stocks experience larger negative abnormal returns (ARs) and cumulative abnormal returns (CARs) relative to non-QSSR stocks, and the difference in CARs is positively related to investor heterogeneity. The results indicate that short selling has mixed effects on stock prices. Removing short-sale constraints can improve liquidity and reduce price bubbles, but can also increase return volatility and amplify market crashes

Customer engagement value (CEV) in the subscription economy: a systematic literature review

The subscription model, prominent within the ‘subscription economy’ (SE), is now a popular form of business within many industries. In simple terms, a subscription model entails two parties (customers and firms) entering into an agreement whereby the patron commits to make regular payments to the supplier, who in exchange periodically delivers an agreed bundle of goods and/or services. Although mostly applied within Business-to-Consumer (B2C) markets (e.g. entertainment services, newspapers and media industry, software licences), the subscription model can be found in Business-to-Business (B2B) markets also (e.g. Rolls Royce ‘Power-by-the-hour model’). This unique form of commerce (i.e. committed repeat patronage) creates an alternative relationship between the buyer and seller to other more traditional forms of business

Deriving reciprocal value in a subscription economy: a customer engagement theory perspective

The theory of Customer Engagement (CE) has been heavily researched and written about over many years, but to date nobody has specifically studied how the theory of CE applies within the Subscription Economy (SE). The SE is growing rapidly, and significantly faster than many other forms of commerce, and some regulators and consumer watchdogs have now highlighted concerns around certain practices by various firms operating in the SE, relating to “negative options” and customers feeling “trapped” by their subscriptions. This research evaluates the reciprocal value that customers and firms have in the SE from a CE perspective. Our contribution is twofold, first this research identifies how value is perceived in the SE by developing a Customer Engagement-based framework. Second, this research provides guidance on how firms operating in the SE should address some of the current challenges emerging in this new form of market