A Review on Identification of Contextual Similar Sentences

The task of identifying contextual similar sentences plays a crucial role in various natural language processing applications such as information retrieval, paraphrase detection, and question answering systems. This paper presents a comprehensive review of the methodologies, techniques, and advancements in the identification of contextual similar sentences. Beginning with an overview of the importance and challenges associated with this task, the paper delves into the various approaches employed, including traditional similarity metrics, deep learning architectures, and transformer-based models. Furthermore, the review explores different datasets and evaluation metrics used to assess the performance of these methods. Additionally, the paper discusses recent trends, emerging research directions, and potential applications in the field. By synthesizing existing literature, this review aims to provide researchers and practitioners with insights into the state-of-the-art techniques and future avenues for advancing the identification of contextual similar sentences

Clustering Data Text Based on Semantic

Clustering is one of the most important data mining techniques which categorize a large number of unordered text documents into meaningful and coherent clusters. Most of text clustering algorithms do not consider the semantic relationships between words and do not have the ability to recognize and use the semantic concepts.In this paper, a new algorithm has been presented to cluster texts based on meanings of the words. First, a new method has been presented to find semantic relationship between words based on Wordnet ontology then, text data is clustered using the proposed method and hierarchical clustering algorithm. Documents are preprocessed, converted to vector space model, and then are clustered using the proposed algorithm semantically. The experimental results show that the quality and accuracy of the proposed algorithm are more reliable than the existing hierarchical clustering algorithms

Model of a semantic web meta-browser based on a general knowledge taxonomy, a general domain ontology, specific ontologies and user profile

Web search has become one of the most important fields of research around the world. They are many reasonsincluding: the fast-growing nature of information sources; the search necessity for information closer to specificuser requirements; the need to reduce search time; and the desire to take into account the semantics of terms usedwhen doing search queries. This paper shows a semantic meta-web search model called XGhobi which uses indexedresources by Google, Yahoo! and Bing. The XGhobi engine combines a general taxonomy of knowledge, a generaldomain ontology –WordNet-, a set of specific domain ontologies, and user profile management to improve therelevance of recovered documents in both English and Spanish. A detailed description of the meta-web searchengine’s components, some user interfaces and its results and its assessments are shown. The assessment covers theobtained precision on tests done by users.La búsqueda web en los últimos años se ha convertido en una de las áreas de investigación más importantes delmundo, debido entre otras cosas: al crecimiento acelerado de las fuentes de información, a la necesidad de contar coninformación más relevante a los requerimientos específicos de cada usuario, a la exploración de menores tiempos debúsqueda y a la falta de usar la semántica de los términos implicados en las consultas. En este artículo se presentael modelo de un meta-buscador (usa los recursos indexados por Google, Yahoo! y Bing) web semántico llamadoXGhobi, que incorpora una taxonomía general de conocimiento, una ontología de dominio general (WordNet), unconjunto de ontologías de dominio específico y el perfil de los usuarios para mejorar la relevancia de los documentosrecuperados tanto en inglés como en español. Se describe en detalle los componentes del meta-buscador, algunasinterfaces de usuario y los resultados de su evaluación. La evaluación del sistema muestra la precisión obtenida enpruebas realizadas con usuarios

Modelo de un meta-buscador web semántico basado en una taxonomía general de conocimiento, una ontología de dominio general, ontologías específicas y perfil de usuario

La búsqueda web en los últimos años se ha convertido en una de las áreas de investigación más importantes delmundo, debido entre otras cosas: al crecimiento acelerado de las fuentes de información, a la necesidad de contar coninformación más relevante a los requerimientos específicos de cada usuario, a la exploración de menores tiempos debúsqueda y a la falta de usar la semántica de los términos implicados en las consultas. En este artículo se presentael modelo de un meta-buscador (usa los recursos indexados por Google, Yahoo! y Bing) web semántico llamadoXGhobi, que incorpora una taxonomía general de conocimiento, una ontología de dominio general (WordNet), unconjunto de ontologías de dominio específico y el perfil de los usuarios para mejorar la relevancia de los documentosrecuperados tanto en inglés como en español. Se describe en detalle los componentes del meta-buscador, algunasinterfaces de usuario y los resultados de su evaluación. La evaluación del sistema muestra la precisión obtenida enpruebas realizadas con usuarios.Web search has become one of the most important fields of research around the world. They are many reasonsincluding: the fast-growing nature of information sources; the search necessity for information closer to specificuser requirements; the need to reduce search time; and the desire to take into account the semantics of terms usedwhen doing search queries. This paper shows a semantic meta-web search model called XGhobi which uses indexedresources by Google, Yahoo! and Bing. The XGhobi engine combines a general taxonomy of knowledge, a generaldomain ontology –WordNet-, a set of specific domain ontologies, and user profile management to improve therelevance of recovered documents in both English and Spanish. A detailed description of the meta-web searchengine’s components, some user interfaces and its results and its assessments are shown. The assessment covers theobtained precision on tests done by users

Procedimento para a construção de índices semânticos baseados em ontologias de domínio específico

The current on-line search systems are still far from providing users with contextualized and accurate answers because users have to make additional efforts to filter and evaluate information supplied to them. One of the ways to improve the results is to create semantic indexes that incorporate knowledge and intelligent processing of resources. When it comes to the implementation of semantic indexes, however, there is a wide range of research studies with their own procedures and lengthy conceptualization, implementation, and refinement processes. Thus, it becomes of the utmost importance to define an instrument that allows creating these kinds of structures in a more structured and efficient manner. This work proposes a procedure that makes it possible to create semantic indexes based on domain-specific ontologies. The methodology entailed creating a state of the art of the various existing proposals and drawing a general procedure that incorporates the best practice for creating semantic indexes. Then, a semantic index was created of the domain of plants and their components. The results demonstrate that the defined process is a good instrument that guides implementation of these kinds of structures with a high degree of customization. Nevertheless, it also shows that the process depends on other variables in building and processing the index, so the design needs to be re-examined until the desirable results are obtained.Los sistemas de búsqueda web actual, aún están lejos de ofrecer respuestas completamente contextualizadas y precisas a los usuarios, ya que éstos deben hacer esfuerzos adicionales de filtrado y evaluación de la información proporcionada. Una forma de mejorar los resultados, es mediante la creación de índices semánticos, los cuales incorporan conocimiento y procesamiento inteligente de los recursos. Sin embargo, al momento de implementar los índices semánticos, existen variadas investigaciones con procedimientos propios y con procesos largos de conceptualización, implementación y afinación. Es así, como se vuelve importante definir una herramienta que permita crear este tipo de estructuras de una manera más estructurada y eficiente. El presente trabajo propone un procedimiento que permite crear índices semánticos a partir de ontologías de dominio específico. La metodología utilizada fue la creación de un estado del arte de las diferentes propuestas existentes y posteriormente la abstracción de un procedimiento general que incorpore las mejores prácticas de creación de índices semánticos. Posteriormente, se creó un índice semántico el dominio de las plantas y sus componentes. Los resultados permiten establecer que el proceso definido es una buena herramienta para guiar la implementación de este tipo de estructuras con un alto grado de personalización. Sin embargo, también evidenció que el proceso depende otras variables al momento de construir y trabajar con el índice y por lo tanto se debe reevaluar el diseño hasta obtener los resultados deseados.Os atuais sistemas de busca na web, estão ainda longe de fornecer respostas plenamente contextualizadas e precisas aos usuários, uma vez que eles devem fazer esforços extras de filtragem e avaliação das informações fornecidas. Uma forma de melhorar os resultados é através da criação de índices semânticos, que incorporam conhecimento e processamento inteligente dos recursos. No entanto, no momento de implementar os índices semânticos, existem variadas investigações com procedimentos próprios e com longos processos de conceituação, implementação e ajuste. É assim que se torna importante definir uma ferramenta que permita criar este tipo de estruturas de uma maneira mais estruturada e eficiente. Este artigo propõe um procedimento que permite criar índices semânticos a partir de ontologias de domínio específico. A metodologia usada foi a criação de um estado de arte das diferentes propostas existentes e posteriormente a abstração de um procedimento geral que incorpore as melhores práticas de criação de índices semânticos. Posteriormente, foi criado um índice semântico de masterização das plantas e seus componentes. Os resultados permitem estabelecer que o processo definido é uma boa ferramenta para orientar a implementação deste tipo de estruturas com um alto grau de personalização. No entanto, também revelou que o processo depende de outras variáveis no momento de construir e trabalhar com o índice e, portanto, o projeto deve ser reavaliado até obter os resultados desejado

Nature inspired computational intelligence for financial contagion modelling

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Financial contagion refers to a scenario in which small shocks, which initially affect only a few financial institutions or a particular region of the economy, spread to the rest of the financial sector and other countries whose economies were previously healthy. This resembles the “transmission” of a medical disease. Financial contagion happens both at domestic level and international level. At domestic level, usually the failure of a domestic bank or financial intermediary triggers transmission by defaulting on inter-bank liabilities, selling assets in a fire sale, and undermining confidence in similar banks. An example of this phenomenon is the failure of Lehman Brothers and the subsequent turmoil in the US financial markets. International financial contagion happens in both advanced economies and developing economies, and is the transmission of financial crises across financial markets. Within the current globalise financial system, with large volumes of cash flow and cross-regional operations of large banks and hedge funds, financial contagion usually happens simultaneously among both domestic institutions and across countries. There is no conclusive definition of financial contagion, most research papers study contagion by analyzing the change in the variance-covariance matrix during the period of market turmoil. King and Wadhwani (1990) first test the correlations between the US, UK and Japan, during the US stock market crash of 1987. Boyer (1997) finds significant increases in correlation during financial crises, and reinforces a definition of financial contagion as a correlation changing during the crash period. Forbes and Rigobon (2002) give a definition of financial contagion. In their work, the term interdependence is used as the alternative to contagion. They claim that for the period they study, there is no contagion but only interdependence. Interdependence leads to common price movements during periods both of stability and turmoil. In the past two decades, many studies (e.g. Kaminsky et at., 1998; Kaminsky 1999) have developed early warning systems focused on the origins of financial crises rather than on financial contagion. Further authors (e.g. Forbes and Rigobon, 2002; Caporale et al, 2005), on the other hand, have focused on studying contagion or interdependence. In this thesis, an overall mechanism is proposed that simulates characteristics of propagating crisis through contagion. Within that scope, a new co-evolutionary market model is developed, where some of the technical traders change their behaviour during crisis to transform into herd traders making their decisions based on market sentiment rather than underlying strategies or factors. The thesis focuses on the transformation of market interdependence into contagion and on the contagion effects. The author first build a multi-national platform to allow different type of players to trade implementing their own rules and considering information from the domestic and a foreign market. Traders’ strategies and the performance of the simulated domestic market are trained using historical prices on both markets, and optimizing artificial market’s parameters through immune - particle swarm optimization techniques (I-PSO). The author also introduces a mechanism contributing to the transformation of technical into herd traders. A generalized auto-regressive conditional heteroscedasticity - copula (GARCH-copula) is further applied to calculate the tail dependence between the affected market and the origin of the crisis, and that parameter is used in the fitness function for selecting the best solutions within the evolving population of possible model parameters, and therefore in the optimization criteria for contagion simulation. The overall model is also applied in predictive mode, where the author optimize in the pre-crisis period using data from the domestic market and the crisis-origin foreign market, and predict in the crisis period using data from the foreign market and predicting the affected domestic market

Nanoscale simulation of crystal defects with application to mantle minerals

Minor and trace elements can influence the chemical and physical properties of the Earth's mantle, whether by forming separate minerals that can host trace elements at far higher concentrations than major mantle minerals, or by influencing physical properties of major minerals, for instance by enhancing diffusion or pinning topological defects. The present study uses atomistic computational modeling to investigate the properties of calcium phosphate minerals at mantle pressures, and to determine if cation vacancies can lubricate dislocation glide in mantle minerals. With their large, high-coordination cation sites, calcium phosphate minerals can potentially dissolve large quantities of incompatible elements, and may be an important mantle reservoirs for these elements. Quantum mechanical calculations are used to determine the variation of structure and properties of apatite, a common low-pressure phosphate, with the identity of its channel anion. The crystal structure and compressibility are both found to vary substantially with channel anion identity. Tuite, which forms by the breakdown of apatite at high pressure, may extend the phosphorous cycle beyond the stability field of apatite and into the lower mantle. DFT calculations are used to show that the pressure at which apatite decomposes to form tuite is sensitive to the identity of the channel anion. The calculated bulk moduli of the calcium-hosting sites in tuite are considerably lower than those of the M site in CaSiO3 perovskite (cpv). Atomistic calculations show that strontium and barium impurities partition strongly from cpv into tuite. The second part of this thesis considers the role that dislocations play in hosting vacancy-related defects, and influence that these segregated defects may have on the rheology of mantle minerals. Interatomic potentials are used to calculate energies for the segregation of bare and protonated cation defects to dislocation cores in MgO and forsterite. Vacancies segregate strongly to [100](010) and [001](010) dislocations in forsterite. [100](010) edge dislocations serve as particularly suitable hosts for vacancies on the M1 sub-lattice, while vacant M2 sites, which are energetically unfavorable in the unstrained bulk lattice are more common around [001](010) edge dislocations. Similarly, both {□Mg}″ and {2HMg}X defects segregate strongly to all of the major dislocation slip systems in MgO. For both minerals, cation vacancies will be far higher at dislocation core sites than in the unstrained lattice. Peierls-Nabarro calculations, parameterized using generalized stacking fault energies calculated using plane-wave density functional theory, show that protonated vacancies increase dislocation core widths and reduce the Peierls stresses in MgO. Bare Mg vacancies, especially those on the M2 sub-lattice, similarly reduce g-line energies and Peierls stresses for the dislocations in olivine. The magnitude of this decrease depends strongly on dislocation and the type of the lattice site (i.e. M1 or M2). Concentrations of vacancy related defects are likely to be elevated particularly in mantle wedge, due to the combination of oxidizing conditions and the availability of liquid water from dehydrating phases in the subducting slab, and changes in the olivine deformation fabric in these regions match those predicted in this study