The aim of this master’s thesis is to examine the virtual reference service Ask the Library [Bibblan svarar] from a postmodern perspective. Ask the Library is a Swedish online reference service that is run by the country’s public libraries. The postmodern theories of Jean-François Lyotard are used to study how information is managed and transmitted within the service. From this point-of-view three aspects of the reference service are studied; how the information is affected by the virtual environment, the librarian’s role within the service and finally how the content of the service is managed. The methods for extracting data are a blend of qualitative interviews and online observations. The data is then analyzed from a theoretical viewpoint. The result shows that there are several postmodern tendencies in Ask the Library. Namely the service shows a number of indications toward plurality. This can be related to Lyotard’s theory of the downfall of the grand narratives since postmodern theories celebrate the idea of plurality and diversity. Ask the Library is complex and dynamic in the sense that it adapts its services to the users. In addition to a multilingual service, Ask the Library also offers the users reference help in the form of social network sites like Facebook and Twitter. This makes the service more varied but also deeply complex. The reference service also emphasizes on the librarian’s individual competence and promotes personal knowledge and expertise. In Lyotard’s postmodern theories there is a rejection of absolute and objective truths and this falls in line with the subjectivity that the reference service celebrates. Ask the Library has two different agendas; providing qualitative reference service to the users and also promoting the librarians and their skills. The information, or content, in the service is still organized and under examination by the librarians. Critique of the sources is an important skill for a librarian within Ask the Library to have. These traditional ideas of objective truth are balanced with the new virtual environment that often promotes collective construction of information and knowledge. This study is a two years master’s thesis in the academic field library and information science.

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No. of bitstreams: 1 Texto Dissertação 19_08_2014.pdf: 6873636 bytes, checksum: 0da192bb47f6068fb0ae55317e8ab051 (MD5) Previous issue date: 2014-08-18 / Item merged in doublecheck by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-03-28T19:39:25Z Item was identical to item(s): 108486, 112974 at handle(s): http://hdl.handle.net/11449/110289, http://hdl.handle.net/11449/113866 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Desde o seu surgimento, a Internet, e nela a Web, têm se popularizado de maneira a tornar-se tecnologia essencial de informação e comunicação, tanto nos países desenvolvidos, quanto em países emergentes. Com o advento da Web Colaborativa, as bibliotecas acadêmicas no mundo todo têm enfrentado o desafio de continuamente repensar a maneira como seus serviços vêm sendo disponibilizados de forma a atingir seus usuários, em especial a geração dos nativos digitais. Nesse contexto de dinamicidade tecnológica surgiu a biblioteca denominada 2.0, que passou a oferecer Serviços de Referência Virtual (SRV) disponibilizando em seus sites, dentre outros serviços, a possibilidade de se comunicar com o bibliotecário através de email e posteriormente chats (ou mensagem instantânea) em tempo real. Este estudo objetivou primeiramente apresentar e delinear as características de um software gratuito de videoconferência e chat que usa tecnologia VoiP utilizado para referência em bibliotecas norte-americanas. Encontrou-se que, embora esse software tenha sido implantando em várias bibliotecas universitárias norte-americanas, com o tempo, essas decidiram por descontinuar o seu uso. Portanto, o foco do estudo se ampliou para a análise dos software para os quais essas bibliotecas migraram e as características dos seus sistemas. Analisa-se também as iniciativas de bibliotecas de universidades brasileiras que implantaram o SRV por meio de chat, os software que estão utilizando atualmente e os fatores considerados por essas instituições no momento da decisão pela implantação do sistema. A permissão para a tradução para a língua portuguesa do guia de Boas Práticas, Políticas e Procedimentos do QuestionPoint 24/7 foi obtida a fim de complementar esse estudo e nortear as bibliotecas brasileiras desejosas de disponibilizar o SRV via chat. A metodologia de pesquisa consistiu em um aporte teórico realizado a partir da literatura produzida nacional e internacionalmente sobre o tema, bem como pesquisa exploratória e observações participantes nos sites de bibliotecas universitárias brasileiras e norte-americanas que disponibilizam o SRV via chat. Este estudo concluiu que o SRV via chat traz benefícios à comunidade e coloca a biblioteca em consonância com as demandas tecnológicas de informação e comunicação sendo apropriado à realidade de bibliotecas acadêmicas brasileiras. Ainda, descobriu que algumas bibliotecas norte-americanas estão fazendo o uso de um software para oferecer o que chamam de Serviço de Referência Proativo. / Since its development, the Internet, and the Web in it, has gained popularity and become core technology of information and communication, both in developed countries and emerging countries. With the advent of Collaborative Web, academic libraries worldwide have faced the challenge of continually rethink the way their services is being made available to achieve its patrons, especially the generation of digital natives. In this context of technological dynamism, Library 2.0 arose, offering Virtual Reference Service (VRS), making available on their websites, among other services, the possibility to communicate with the librarian via email and then chat (or Instant Message) in real time. This study aimed primarily to present and outline the features of a free chat and video chat software that uses VoIP technology used for reference in U.S. libraries. It was found that although this software had been used by several U.S. academic libraries, with time, these institutions decided to discontinue its use. Therefore, the focus of the study was extended to the analysis of the software for which those libraries migrated and the features of their systems. The study also analyses the initiatives of Brazilian academic libraries that have implemented the SRV via chat, the software they are currently using and the factors considered by these institutions when deciding the implementation. Permission to translate QuestionPoint 24/7 Best Practices, Policies and Procedures into Portuguese was obtained in order to complement this study and guide the Brazilian libraries wishing to provide the VRS chat. The research methodology consisted of a theoretical contribution from the literature produced nationally and internationally on the topic, as well as exploratory research and participant observations on the Brazilian and American university libraries which offer the SRV chat on their website. This study concluded that VRS via chat brings benefits to the community and puts the library in line with the technological demands of information and communication therefore it is appropriate to the reality of Brazilian academic libraries. In addition, the investigation found out that some American libraries are making use of software to offer what is being called Proactive Reference Service.

Este trabalho tem o intuito, de apresentar alguns conceitos, relativos à identifi cação de sistemás, tanto lineares quanto não linearep, além da ideia de referência virtual para, em conjunto com a teoria de projeto "de controladores baseados em dados, propor uma forrha de projeto de controladores não lineares baseados em identificação de sistemas. A utilização de referência virtual para a obtenção dos sinais necessários para a caracterização do controlador ótimo de um sistema e utilizado no método VRFT (Virtual Reference Feedback Tuning). Este método serve como base para o desenvolvimento da proposta deste trabalho que, em conjunto com a teoria de identificação de sistemas não lineares, permite a obteriçãci do controlador ótimo que leva o sistema a se comportar como especificado em malha fechada. Em especial optou-se pela caracterização do controlador utilizando estrutura de modelos racional, por esta ser uma classe bastante abrangente no que - diz respeito à quantidade de sistemas reais que ela é capaz de descrever. Fara demonstrar o potencial do método proposto para projeto de controladores, são apresentados ecemplos ilustrativos em situações onde o controlador ideal consegue ser representado pela classe de modelos, e quando isso não é possível. / This work aims to present some concepts related to linear and nonlinear system identification, as well as the •concept of virtual reference that, together with data based controller design's theory, provides design framework for nonlinear controllers. The Virtual Reference Feedback Tuning method (VRFT) is used as a basis for the current proposal, where we propose to unite nonlinear system identification algorithms and virtual reference to obtain the ideal controller: the one which makes the system behave as desired in closed loop. It was choosen to model the controller as a rational model due the wide variety of practical systems that can be represented by this model structure. For rational system identification we used an iterative algorithm which, based on the signal from input and output of the pIant, allows to identify the parameters of the pre defined controller structure with the signals obtained by virtual reference. To demonstrate the operation of the proposed identification controller methodology, illustrative examples are presented in situations where the ideal controller can be represented by the class of modeIs, and also when it is not possible.

Este trabalho tem o intuito, de apresentar alguns conceitos, relativos à identifi cação de sistemás, tanto lineares quanto não linearep, além da ideia de referência virtual para, em conjunto com a teoria de projeto "de controladores baseados em dados, propor uma forrha de projeto de controladores não lineares baseados em identificação de sistemas. A utilização de referência virtual para a obtenção dos sinais necessários para a caracterização do controlador ótimo de um sistema e utilizado no método VRFT (Virtual Reference Feedback Tuning). Este método serve como base para o desenvolvimento da proposta deste trabalho que, em conjunto com a teoria de identificação de sistemas não lineares, permite a obteriçãci do controlador ótimo que leva o sistema a se comportar como especificado em malha fechada. Em especial optou-se pela caracterização do controlador utilizando estrutura de modelos racional, por esta ser uma classe bastante abrangente no que - diz respeito à quantidade de sistemas reais que ela é capaz de descrever. Fara demonstrar o potencial do método proposto para projeto de controladores, são apresentados ecemplos ilustrativos em situações onde o controlador ideal consegue ser representado pela classe de modelos, e quando isso não é possível. / This work aims to present some concepts related to linear and nonlinear system identification, as well as the •concept of virtual reference that, together with data based controller design's theory, provides design framework for nonlinear controllers. The Virtual Reference Feedback Tuning method (VRFT) is used as a basis for the current proposal, where we propose to unite nonlinear system identification algorithms and virtual reference to obtain the ideal controller: the one which makes the system behave as desired in closed loop. It was choosen to model the controller as a rational model due the wide variety of practical systems that can be represented by this model structure. For rational system identification we used an iterative algorithm which, based on the signal from input and output of the pIant, allows to identify the parameters of the pre defined controller structure with the signals obtained by virtual reference. To demonstrate the operation of the proposed identification controller methodology, illustrative examples are presented in situations where the ideal controller can be represented by the class of modeIs, and also when it is not possible.

Este trabalho tem o intuito, de apresentar alguns conceitos, relativos à identifi cação de sistemás, tanto lineares quanto não linearep, além da ideia de referência virtual para, em conjunto com a teoria de projeto "de controladores baseados em dados, propor uma forrha de projeto de controladores não lineares baseados em identificação de sistemas. A utilização de referência virtual para a obtenção dos sinais necessários para a caracterização do controlador ótimo de um sistema e utilizado no método VRFT (Virtual Reference Feedback Tuning). Este método serve como base para o desenvolvimento da proposta deste trabalho que, em conjunto com a teoria de identificação de sistemas não lineares, permite a obteriçãci do controlador ótimo que leva o sistema a se comportar como especificado em malha fechada. Em especial optou-se pela caracterização do controlador utilizando estrutura de modelos racional, por esta ser uma classe bastante abrangente no que - diz respeito à quantidade de sistemas reais que ela é capaz de descrever. Fara demonstrar o potencial do método proposto para projeto de controladores, são apresentados ecemplos ilustrativos em situações onde o controlador ideal consegue ser representado pela classe de modelos, e quando isso não é possível. / This work aims to present some concepts related to linear and nonlinear system identification, as well as the •concept of virtual reference that, together with data based controller design's theory, provides design framework for nonlinear controllers. The Virtual Reference Feedback Tuning method (VRFT) is used as a basis for the current proposal, where we propose to unite nonlinear system identification algorithms and virtual reference to obtain the ideal controller: the one which makes the system behave as desired in closed loop. It was choosen to model the controller as a rational model due the wide variety of practical systems that can be represented by this model structure. For rational system identification we used an iterative algorithm which, based on the signal from input and output of the pIant, allows to identify the parameters of the pre defined controller structure with the signals obtained by virtual reference. To demonstrate the operation of the proposed identification controller methodology, illustrative examples are presented in situations where the ideal controller can be represented by the class of modeIs, and also when it is not possible.

Noise pollution from road traffic is one of the greatest environmental issues in modern day, and the social cost for road traffic noise was estimated to over 16 billion SEK per year in Sweden in2014. Passive or active control methods can be used to reduce the noise. Active control methods or active noise control is more suitable for attenuating noise in lower frequencies. Active noise control reduces noise by eliminating the noise with a secondary source. There are different control strategies to construct an active noise control system, where the update of the secondary sourceis controlled by an algorithm. There are several different algorithms that are possible to use, and one option is to use a Feedforward Filtered-X Least-Mean-Square (FXLMS) algorithm. It uses control positions where the noise is meant to be reduced and reference signals that measure the noise upstream prior the secondary source. FXLMS also uses a model of the secondary source path to the control position in order to ensure convergence of the algorithm. Although the use of multiple reference signals increases the accuracy of the algorithm, it also increases the convergence time and the practical cost of such an installation. Unfortunately, it can require many reference signals to obtain a sufficient noise reduction when the unwanted noise source is complex and has multiple propagation paths.This study investigates the possibility of producing a new, reduced set of reference signals with a linear combination of the original reference signals that still contain the majority of information needed for suficient noise reduction. This new set of reference signals are sometimes called virtual reference signals. Three different methods of virtual reference signals are analysed; first a constant method using singular-value decomposition on the covariance of the reference signals, second another constant method using singular-value decomposition on the covariance of response estimate from each corresponding reference signal, third an adaptive algorithm updating the linear combination to adapt for incoming data. The different strategies are tested on road test measurements at three different constant speeds, 40km=h; 80km=h and 120km=h, and on data generated from a numerical vehicle model in COMSOL.The results from the analysis indicates that the virtual reference signals could sufficiently reproduce information from the original reference signals to obtain a similar noise reduction with fewer reference signals. However, the virtual reference signals with the adaptive algorithm could not manage to track a transient system where the signal amplitudes are varying over time. Further work is needed to analyse the limits and requirements to obtain virtual reference signals that can represent and track a system even for transient events.

Nätverks-RTK (Real-Time Kinematic) är en metod för positionsbestämning med Global Navigation Satellite System (GNSS) i realtid. Metoden kräver att en driftledningscentral kan kommunicera med de GNSS-mottagare som använder referensstationsnätet, för att bland annat skicka ut korrigerade GNSS-data. I Sverige erbjuder SWEPOS, ett nät av fasta referensstationer, en tjänst för nätverks-RTK-mätning, som förväntas ge en mätosäkerhet på mindre än 15 mm i plan och 25 mm i höjd (över ellipsoiden) (med täckningsfaktorn k = 1 i bägge fallen). Den teknik som idag används av SWEPOS för att utföra positionsbestämning av GNSS-mottagare är Virtuell Referensstation (VRS). VRS kräver tvåvägskommunikation eftersom mottagaren skickar in sin absoluta position till nätverks-RTK-programvaran hos driftledningscentralen, var beräkningarna av korrektionsdata sker, innan de skickas tillbaka till mottagaren. Det finns ett annat alternativ som möjliggör envägskommunikation, nämligen nätverks-RTK-meddelande. Då sänds observationsdata, i form av korrektioner, ut till mottagaren som utför positionsberäkningarna. Syftet med det här examensarbetet var att undersöka nätverks-RTK-meddelande för GNSS-mottagare av tre olika fabrikat med avseende på initialiseringstider, mätosäkerhet, avståndsberoende från närmaste masterstation, och GLONASS-satelliters deltagande i positionsbestämningen. I studien ingick även att utföra några jämförande mätningar med VRS. Undersökningarna gjordes genom upprepade nätverks-RTK-mätningar med GNSS-mottagare från Leica Geosystems, Trimble och Topcon, på tre kända punkter sydöst om Gävle. Tre mätmetoder användes, nätverks-RTK-meddelande med automatiskt nät (tvåvägskommunikation) och statiskt nät (envägskommunikation), samt VRS. De tre mätpunkterna valdes så att avståndet, till den referensstation som användes som en så kallad masterstation, varierade. Studien visade att initialiseringstiderna skiljde mellan de tre mottagarfabrikaten. En anledning till detta var att varje mottagare ominitialiserades från olika lösningslägen. Generellt var mätosäkerheten något högre för statiskt nät. Mätosäkerheten var omkring 11 mm i plan och 19 mm i höjd med det automatiska nätet, samt 13 mm respektive 22 mm i det statiska nätet. Fabrikaten emellan, låg Leica och Trimble på samma nivå, medan Topcon hade ett generellt problem för det statiska nätet, vilket det inte fanns möjlighet att närmare utreda orsaken till. Resultatet visade även att mätosäkerheten påverkas av avståndet till använd masterstation. I några fall var dessa förhållanden linjära. Vid några tillfällen användes inte GLONASS-satelliter i positionsbestämningen. / Network RTK (Real-Time Kinematic) is a method of positioning with Global Navigation Satellite System (GNSS) in real-time. The method requires that a control centre can communicate with the GNSS receiver, which is using the reference station network, for example to send out corrected GNSS data. In Sweden, SWEPOS, which is a network of permanent reference stations for GNSS, offers a service for Network RTK measurement. This is expected to give an uncertainty of less than 15 mm in plane and 25 mm in (ellipsoidal) height (with the coverage factor k = 1 in both cases). The technology currently used by SWEPOS, to perform positioning of a GNSS receiver, is Virtual Reference Station (VRS). VRS requires two-way communication because the receiver submits its navigated location to the control centre, where the calculations of correction data are made, before they are sent back to the receiver. Another alternative is Network RTK messages which make use of one-way communication. Then the observation data are transmitted to the receiver, which performs determination of its position. The purpose of this thesis was to investigate the network RTK messages with GNSS receivers from three different manufacturers with regard to time to fix ambiguities, measurement uncertainty and its dependence on the distance from the master station, and GLONASS satellites presence in the positioning. Also included in the study was the performance of comparative measurements with VRS. The investigations were conducted through repeated network RTK measurements with GNSS receivers from Leica Geosystems, Trimble and Topcon, at three known points south-east of Gävle. Three methods were used, network RTK message with automatic and static networks, and VRS. The three measurement points were chosen so that the distance to the reference station that was used as the so-called master station, varied. The study showed that the time to fix ambiguities differed between the three brands. One reason for this was that each receiver was reinitialized from different steps in the initialization process. In general, the uncertainty in the measurement was slightly higher for the static network. The uncertainty was about 11 mm in plane and 19 mm in height with the automated network, and 13 mm and 22 mm respectively in the static network. Leica and Trimble were at the same level, while Topcon had general problems for the static network, which there was no possibility to closer investigate the reason for. The results also showed that the uncertainty is influenced by the distance to used master station. In some cases, this relationship is linear. On some occasions, GLONASS satellites were not included in the positioning.

The aim of this thesis is to describe of the chat application in the virtual reference services from both theoretical and practical point of view. The theoretical part is based on close reading of the mostly foreign literature. The first introductory chapter discusses the terminology and definition of reference services and then virtual reference services, which have not been settled yet. The second chapter deals with chat application. All phases of the chat application are mentioned, from planning through implementation and marketing to the final evaluation of the service. The third chapter is devoted to chat as a specific form of communication with particular focus on its advantages and disadvantages in the library services. The findings of these chapters are used in the analysis of the chosen virtual reference services. The practical part in the fourth chapter constitutes chat in real use, first in foreign libraries, then in Czech libraries as well. The fifth chapter constitutes the main contribution of the practical part. It describes the chat preparation within the Czech cooperative virtual reference service "Ask your library" in the National Library of the Czech Republic, in which the autor of this thesis participated. The conclusion provides a brief summary.