Сравнительный анализ коллекций научных журналов

The authors developed an approach to comparative analysis of scientific journals collections based on the analysis of co-authors graph and the text model. The use of time series of co-authorship graphs metrics allowed the authors to analyze trends in the development of journal authors. The text model was built using machine learning techniques. The journals content was classified to determine the authenticity degree of various journals and different issues of a single journal via a text model. The authors developed a metric of Content Authenticity Ratio, which allows quantifying the authenticity of journal collections in comparison. Comparative thematic analysis of journals collections was carried out using the thematic model with additive regularization. Based on the created thematic model, the authors constructed thematic profiles of the journals archives in a single thematic basis. The approach developed by the authors was applied to archives of two journals on the Rheumatology for the period 2000–2018. As a benchmark for comparing the co-author’s metrics, public data sets from the SNAP research laboratory at Stanford University were used. As a result, the authors adapted the existing examples of the effective functioning of the authors collaborations in order to improve the work of journals editorial staff. Quantitative comparison of large volumes of texts and metadata of scientific articles was carried out. As a result of the experiment conducted using the developed methods, it was shown that the content authenticity of the selected journals is 89%, co-authorships in one of the journals have a pronounced centrality, which is a distinctive feature of the policy editor. The clarity and consistency of the results confirm the effectiveness of the approach proposed by the authors. The code developed in the course of the experiment in the Python programming language can be used for comparative analysis of other collections of journals in the Russian language.Разработан подход для сравнительного анализа коллекций научных журналов на основе анализа графа соавторств и модели текста. Использование временных рядов метрик графа соавторства позволило провести анализ тенденций в развитии коллабораций авторов журнала. Модель текста была построена с помощью методов машинного обучения. При помощи модели текста была произведена классификация контента журналов для выявления степени аутентичности различных журналов и различных выпусков одного журнала. Разработана метрика Коэффициент контентной аутентичности, позволяющая количественно оценивать аутентичность коллекций журналов в сравнении. Сравнительный тематический анализ коллекций журналов выполнен с использованием тематической модели с аддитивной регуляризацией. На основании созданной тематической модели авторами построены тематические профили архивов журналов в едином тематическом базисе. Разработанный подход был применен к архивам двух журналов по тематике Ревматология за период 2000 – 2018 гг. В качестве эталона для сравнения метрик соавторств были взяты публичные наборы данных научной лаборатории SNAP Стендфордского университета. Проведено сравнение коллабораций соавторов журналов по тематике Ревматология с эталонными коллаборациями авторов. Произведено количественное сопоставление больших объемов текстов и метаданных научных статей. В результате проведенного авторами эксперимента с использованием разработанных методик показано, что контентная аутентичность выбранных журналов составляет 89%, соавторства в одном из журналов имеют ярко выраженную центральность, что является отличительной чертой редакционной политики. Наглядность и непротиворечивость полученных результатов подтверждает эффективность предложенного подхода. Разработанный в ходе эксперимента код на языке программирования Python может быть применен для сравнительного анализа других коллекций журналов на русском языке

Сравнительный анализ коллекций научных журналов

Разработан подход для сравнительного анализа коллекций научных журналов на основе анализа графа соавторств и модели текста. Использование временных рядов метрик графа соавторства позволило провести анализ тенденций в развитии коллабораций авторов журнала. Модель текста была построена с помощью методов машинного обучения. При помощи модели текста была произведена классификация контента журналов для выявления степени аутентичности различных журналов и различных выпусков одного журнала. Разработана метрика Коэффициент контентной аутентичности, позволяющая количественно оценивать аутентичность коллекций журналов в сравнении. Сравнительный тематический анализ коллекций журналов выполнен с использованием тематической модели с аддитивной регуляризацией. На основании созданной тематической модели авторами построены тематические профили архивов журналов в едином тематическом базисе. Разработанный подход был применен к архивам двух журналов по тематике Ревматология за период 2000 – 2018 гг. В качестве эталона для сравнения метрик соавторств были взяты публичные наборы данных научной лаборатории SNAP Стендфордского университета. Проведено сравнение коллабораций соавторов журналов по тематике Ревматология с эталонными коллаборациями авторов. Произведено количественное сопоставление больших объемов текстов и метаданных научных статей. В результате проведенного авторами эксперимента с использованием разработанных методик показано, что контентная аутентичность выбранных журналов составляет 89%, соавторства в одном из журналов имеют ярко выраженную центральность, что является отличительной чертой редакционной политики. Наглядность и непротиворечивость полученных результатов подтверждает эффективность предложенного подхода. Разработанный в ходе эксперимента код на языке программирования Python может быть применен для сравнительного анализа других коллекций журналов на русском языке

Text Augmentation: Inserting markup into natural language text with PPM Models

This thesis describes a new optimisation and new heuristics for automatically marking up XML documents. These are implemented in CEM, using PPMmodels. CEM is significantly more general than previous systems, marking up large numbers of hierarchical tags, using n-gram models for large n and a variety of escape methods. Four corpora are discussed, including the bibliography corpus of 14682 bibliographies laid out in seven standard styles using the BIBTEX system and markedup in XML with every field from the original BIBTEX. Other corpora include the ROCLING Chinese text segmentation corpus, the Computists’ Communique corpus and the Reuters’ corpus. A detailed examination is presented of the methods of evaluating mark up algorithms, including computation complexity measures and correctness measures from the fields of information retrieval, string processing, machine learning and information theory. A new taxonomy of markup complexities is established and the properties of each taxon are examined in relation to the complexity of marked-up documents. The performance of the new heuristics and optimisation is examined using the four corpora

Using semantic knowledge to improve compression on log files

With the move towards global and multi-national companies, information technology infrastructure requirements are increasing. As the size of these computer networks increases, it becomes more and more difficult to monitor, control, and secure them. Networks consist of a number of diverse devices, sensors, and gateways which are often spread over large geographical areas. Each of these devices produce log files which need to be analysed and monitored to provide network security and satisfy regulations. Data compression programs such as gzip and bzip2 are commonly used to reduce the quantity of data for archival purposes after the log files have been rotated. However, there are many other compression programs which exist - each with their own advantages and disadvantages. These programs each use a different amount of memory and take different compression and decompression times to achieve different compression ratios. System log files also contain redundancy which is not necessarily exploited by standard compression programs. Log messages usually use a similar format with a defined syntax. In the log files, all the ASCII characters are not used and the messages contain certain "phrases" which often repeated. This thesis investigates the use of compression as a means of data reduction and how the use of semantic knowledge can improve data compression (also applying results to different scenarios that can occur in a distributed computing environment). It presents the results of a series of tests performed on different log files. It also examines the semantic knowledge which exists in maillog files and how it can be exploited to improve the compression results. The results from a series of text preprocessors which exploit this knowledge are presented and evaluated. These preprocessors include: one which replaces the timestamps and IP addresses with their binary equivalents and one which replaces words from a dictionary with unused ASCII characters. In this thesis, data compression is shown to be an effective method of data reduction producing up to 98 percent reduction in filesize on a corpus of log files. The use of preprocessors which exploit semantic knowledge results in up to 56 percent improvement in overall compression time and up to 32 percent reduction in compressed size.TeXpdfTeX-1.40.

The analysis of enumerative source codes and their use in Burrows‑Wheeler compression algorithms

In the late 20th century the reliable and efficient transmission, reception and storage of information proved to be central to the most successful economies all over the world. The Internet, once a classified project accessible to a selected few, is now part of the everyday lives of a large part of the human population, and as such the efficient storage of information is an important part of the information economy. The improvement of the information storage density of optical and electronic media has been remarkable, but the elimination of redundancy in stored data and the reliable reconstruction of the original data is still a desired goal. The field of source coding is concerned with the compression of redundant data and its reliable decompression. The arithmetic source code, which was independently proposed by J. J. Rissanen and R. Pasco in 1976, revolutionized the field of source coding. Compression algorithms that use an arithmetic code to encode redundant data are typically more effective and computationally more efficient than compression algorithms that use earlier source codes such as extended Huffman codes. The arithmetic source code is also more flexible than earlier source codes, and is frequently used in adaptive compression algorithms. The arithmetic code remains the source code of choice, despite having been introduced more than 30 years ago. The problem of effectively encoding data from sources with known statistics (i.e. where the probability distribution of the source data is known) was solved with the introduction of the arithmetic code. The probability distribution of practical data is seldomly available to the source encoder, however. The source coding of data from sources with unknown statistics is a more challenging problem, and remains an active research topic. Enumerative source codes were introduced by T. J. Lynch and L. D. Davisson in the 1960s. These lossless source codes have the remarkable property that they may be used to effectively encode source sequences from certain sources without requiring any prior knowledge of the source statistics. One drawback of these source codes is the computationally complex nature of their implementations. Several years after the introduction of enumerative source codes, J. G. Cleary and I. H. Witten proved that approximate enumerative source codes may be realized by using an arithmetic code. Approximate enumerative source codes are significantly less complex than the original enumerative source codes, but are less effective than the original codes. Researchers have become more interested in arithmetic source codes than enumerative source codes since the publication of the work by Cleary and Witten. This thesis concerns the original enumerative source codes and their use in Burrows–Wheeler compression algorithms. A novel implementation of the original enumerative source code is proposed. This implementation has a significantly lower computational complexity than the direct implementation of the original enumerative source code. Several novel enumerative source codes are introduced in this thesis. These codes include optimal fixed–to–fixed length source codes with manageable computational complexity. A generalization of the original enumerative source code, which includes more complex data sources, is proposed in this thesis. The generalized source code uses the Burrows–Wheeler transform, which is a low–complexity algorithm for converting the redundancy of sequences from complex data sources to a more accessible form. The generalized source code effectively encodes the transformed sequences using the original enumerative source code. It is demonstrated and proved mathematically that this source code is universal (i.e. the code has an asymptotic normalized average redundancy of zero bits). AFRIKAANS : Die betroubare en doeltreffende versending, ontvangs en berging van inligting vorm teen die einde van die twintigste eeu die kern van die mees suksesvolle ekonomie¨e in die wˆereld. Die Internet, eens op ’n tyd ’n geheime projek en toeganklik vir slegs ’n klein groep verbruikers, is vandag deel van die alledaagse lewe van ’n groot persentasie van die mensdom, en derhalwe is die doeltreffende berging van inligting ’n belangrike deel van die inligtingsekonomie. Die verbetering van die bergingsdigteid van optiese en elektroniese media is merkwaardig, maar die uitwissing van oortolligheid in gebergde data, asook die betroubare herwinning van oorspronklike data, bly ’n doel om na te streef. Bronkodering is gemoeid met die kompressie van oortollige data, asook die betroubare dekompressie van die data. Die rekenkundige bronkode, wat onafhanklik voorgestel is deur J. J. Rissanen en R. Pasco in 1976, het ’n revolusie veroorsaak in die bronkoderingsveld. Kompressiealgoritmes wat rekenkundige bronkodes gebruik vir die kodering van oortollige data is tipies meer doeltreffend en rekenkundig meer effektief as kompressiealgoritmes wat vroe¨ere bronkodes, soos verlengde Huffman kodes, gebruik. Rekenkundige bronkodes, wat gereeld in aanpasbare kompressiealgoritmes gebruik word, is ook meer buigbaar as vroe¨ere bronkodes. Die rekenkundige bronkode bly na 30 jaar steeds die bronkode van eerste keuse. Die probleem om data wat afkomstig is van bronne met bekende statistieke (d.w.s. waar die waarskynlikheidsverspreiding van die brondata bekend is) doeltreffend te enkodeer is opgelos deur die instelling van rekenkundige bronkodes. Die bronenkodeerder het egter selde toegang tot die waarskynlikheidsverspreiding van praktiese data. Die bronkodering van data wat afkomstig is van bronne met onbekende statistieke is ’n groter uitdaging, en bly steeds ’n aktiewe navorsingsveld. T. J. Lynch and L. D. Davisson het tel–bronkodes in die 1960s voorgestel. Tel– bronkodes het die merkwaardige eienskap dat bronsekwensies van sekere bronne effektief met hierdie foutlose kodes ge¨enkodeer kan word, sonder dat die bronenkodeerder enige vooraf kennis omtrent die statistieke van die bron hoef te besit. Een nadeel van tel–bronkodes is die ho¨e rekenkompleksiteit van hul implementasies. J. G. Cleary en I. H. Witten het verskeie jare na die instelling van tel–bronkodes bewys dat benaderde tel–bronkodes gerealiseer kan word deur die gebruik van rekenkundige bronkodes. Benaderde tel–bronkodes het ’n laer rekenkompleksiteit as tel–bronkodes, maar benaderde tel–bronkodes is minder doeltreffend as die oorspronklike tel–bronkodes. Navorsers het sedert die werk van Cleary en Witten meer belangstelling getoon in rekenkundige bronkodes as tel–bronkodes. Hierdie tesis is gemoeid met die oorspronklike tel–bronkodes en die gebruik daarvan in Burrows–Wheeler kompressiealgoritmes. ’n Nuwe implementasie van die oorspronklike tel–bronkode word voorgestel. Die voorgestelde implementasie het ’n beduidende laer rekenkompleksiteit as die direkte implementasie van die oorspronklike tel–bronkode. Verskeie nuwe tel–bronkodes, insluitende optimale vaste–tot–vaste lengte tel–bronkodes met beheerbare rekenkompleksiteit, word voorgestel. ’n Veralgemening van die oorspronklike tel–bronkode, wat meer komplekse databronne insluit as die oorspronklike tel–bronkode, word voorgestel in hierdie tesis. The veralgemeende tel–bronkode maak gebruik van die Burrows–Wheeler omskakeling. Die Burrows–Wheeler omskakeling is ’n lae–kompleksiteit algoritme wat die oortolligheid van bronsekwensies wat afkomstig is van komplekse databronne omskakel na ’n meer toeganklike vorm. Die veralgemeende bronkode enkodeer die omgeskakelde sekwensies effektief deur die oorspronklike tel–bronkode te gebruik. Die universele aard van hierdie bronkode word gedemonstreer en wiskundig bewys (d.w.s. dit word bewys dat die kode ’n asimptotiese genormaliseerde gemiddelde oortolligheid van nul bisse het). CopyrightDissertation (MEng)--University of Pretoria, 2010.Electrical, Electronic and Computer Engineeringunrestricte

The construction and evaluation of statistical models of melodic structure in music perception and composition

The prevalent approach to developing cognitive models of music perception and composition is to construct systems of symbolic rules and constraints on the basis of extensive music-theoretic and music-analytic knowledge. The thesis proposed in this dissertation is that statistical models which acquire knowledge through the induction of regularities in corpora of existing music can, if examined with appropriate methodologies, provide significant insights into the cognitive processing involved in music perception and composition. This claim is examined in three stages. First, a number of statistical modelling techniques drawn from the fields of data compression, statistical language modelling and machine learning are subjected to empirical evaluation in the context of sequential prediction of pitch structure in unseen melodies. This investigation results in a collection of modelling strategies which together yield significant performance improvements over existing methods. In the second stage, these statistical systems are used to examine observed patterns of expectation collected in previous psychological research on melody perception. In contrast to previous accounts of this data, the results demonstrate that these patterns of expectation can be accounted for in terms of the induction of statistical regularities acquired through exposure to music. In the final stage of the present research, the statistical systems developed in the first stage are used to examine the intrinsic computational demands of the task of composing a stylistically successful melody The results suggest that the systems lack the degree of expressive power needed to consistently meet the demands of the task. In contrast to previous research, however, the methodological framework developed for the evaluation of computational models of composition enables a detailed empirical examination and comparison of such models which facilitates the identification and resolution of their weaknesses

Tag based models of English text

The problem of compressing English text is important both because of the ubiquity of English as a target for compression and because of the light that compression can shed on the structure of English. English text is examined in conjunction with additional information about the parts of speech of each word in the text (these are referred to as “tags”). It is shown that the tags plus the text can be compressed more than the text alone. Essentially the tags can be compressed for nothing or even a small net saving in size. A comparison is made of a number of different ways of integrating compression of tags and text using an escape mechanism similar to PPM. These are also compared with standard word based and character based compression programs. The result is that the tag character and word based schemes always outperform the character based schemes. Overall, the tag based schemes outperform the word based schemes. We conclude by conjecturing that tags chosen for compression rather than linguistic purposes would perform even better