Teses / dissertações: "Electronic WOM"

1

Bengtsson, Anton, Martin Alm e Pär Ivarsson. "Bakomliggande motiv, alla har dem : En kvalitativ fallstudie om varför kunder sprider e-WOM på sociala medier". Thesis, Linnéuniversitetet, Institutionen för marknadsföring (MF), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35414.

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Kurs/nivå: 2FE16E, Kandidatuppsats Författare: Martin Alm, Anton Bengtsson, Pär Ivarsson Handledare: Dan Halvarsson Examinator: Åsa Devine Titel: Bakomliggande motiv, alla har dem. Nyckelord: e-WOM, electronic word-of-mouth, e-wom motiv, sociala medier, Facebook. Bakgrund: Att veta varför kunder delar med sig och sprider information om företag har blivit viktigt för företag om de vill effektivisera sin marknadsföring på Internet. Mycket av den tidigare forskningen gällande e-WOM har fokuserat på informationsspridningens effekt men inte vad kunder har för bakomliggande motiv till att sprida e- WOM. Forskning har också visat att det finns skillnader i hur kunder sprider e-WOM på sociala medier jämfört med övriga plattformar på Internet. Det är därmed betydelsefullt att på ett djupgående sätt utforska vad kunder, utifrån deras perspektiv, har för bakomliggande motiv till att sprida information om företag på sociala medier. Forskningsfråga: Varför sprider kunder e-WOM på sociala medier? Syfte: Syftet är att utforska kunders bakomliggande motiv till spridning av e-WOM på sociala medier. Metod: Utförd som en fallstudie av ett enda fall genom sex stycken semi-strukturerade intervjuer. Slutsats: Undersökningen visade att det finns 15 bakomliggande motiv till kunders spridning av e-WOM på sociala medier. Några av de bakomliggande motiven är överraskningsmomentet, möjligheten att påverka andra, få bekräftelse samt att vänner och bekanta ska gynnas av informationsspridningen.
Course/Level: 2FE16E, Bachelor Thesis Authors: Martin Alm, Anton Bengtsson, Pär Ivarsson Tutor: Dan Halvarsson Examiner: Åsa Devine Title: Underlying motives, everybody has them. Keywords: e-WOM, electronic word-of-mouth, e-wom motives, social media, Facebook. Background: Knowing why customers will share and spread information about companies has become important for companies if they want to improve their marketing on the Internet. Much of the previous research regarding e-WOM has focused on the effect but not about customers underlying motives to spread e-WOM. Research has also shown that there are differences in how customers spreading e-WOM on social media compared to other platforms on the Internet. It is therefore significant that in a profound way explore what customers’, from their perspective, have for underlying motives to spread information about companies on social media are. Research question: Why do customers spread e-WOM on social media? Purpose: The purpose of this thesis is to explore customers underlying motives to spread e-WOM on social media. Methodology: Conducted as a single embedded case study through six semi-structured interviews. Conclusion: The empirical investigation revealed that there are 15 underlying motives for customers to spread e-WOM on social media. Some of the underlying motives are the element of surprise, the ability to influence others, to obtain confirmation and for friends and acquaintances to benefit from the information.

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Wester, Emma. "Negativ word of mouth : olika WOM-källors inflytande på köpbeslutet". Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-11129.

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Word-of-mouth har länge varit ett intressant och viktigt fenomen inom marknadsföringen. Med introduktionen av Internet och den växande populariteten av sociala medier, så har word-of-mouth förändrats och är nu tillgänglig för många fler konsumenter online och världen över. Word-of-mouth som sker över Internet har fått namnet elektronisk word-of-mouth (förkortat eWOM). Denna studie har undersökt skillnader i inflytandet av olika word-of-mouth-källor, specifikt traditionell muntlig WOM och eWOM. Detta för att se om det finns några skillnader i hur konsumenter söker och tar del av WOM-information inför köpbeslut av nya produkter eller tjänster. Denna studie har också perspektivet att endast kolla på inflytandet av negativa WOM-källor och hur dessa påverkar konsumenters köpbeslut. Studien har genomförts med hjälp utav ett elektroniskt frågeformulär som distribuerats genom Högskolan i Borås studenter samt genom Facebook. Frågeformuläret består av frågor och avsnitt gällande hur viktigt WOM är för konsumenter innan köp av en tidigare oprövad produkt eller tjänst, trovärdigheten av WOM informationen, hur WOM kan ändra ens attityd samt sannolikheten att man avstår köp på grund av negativ WOM.Resultatet från frågeformuläret visar på att traditionell muntlig WOM fortfarande anses vara den bästa WOM-källan, den som används mest och anses vara den mest trovärdiga källan för WOM och fick högst poäng i alla kategorier från frågeformuläret. eWOM från ratingsidor rankades som näst bäst medan eWOM från ens Facebookvänner ansåg vara det sämsta alternativet för eWOM i alla kategorier. Slutsatsen dras därför att negativ WOM-information influerar konsumenter på olika vis beroende på vilken WOM-källa det kommer ifrån. Traditionell muntlig WOM anses vara det bästa, även om eWOM används mycket så anses det inte vara lika trovärdigt och informativt.
Word-of-mouth has been an important phenomenon in marketing for a very long time. With the introduction of the Internet and the growing popularity of social media, word-of-mouth communication has changed and is now available for consumers from all over the world with just the click of a mouse on your computer. This phenomenon has been given the name electronic word-of-mouth (eWOM). This study has examined the influence of different WOM-sources, specifically traditional oral WOM and electronic WOM to see if there are any differences in how consumers search and use different WOM-information in their purchase decision. This study has also taken an approach to only look at the influence of negative word-of-mouth from different WOM-sources and their influence. To research this an electronic questionnaire has been used and distributed to student at the University of Borås and also over Facebook. The questionnaire consists of questions regarding how important looking for WOM information before a purchase it, trustworthiness of WOM, how WOM can change your attitude to a product or service and the possibility of not going through with a purchase based on information from WOM-sources.Results from the questionnaire shows that traditional oral WOM is still considered to be the best, most used and trustworthy source of WOM as it scored highest in all categories of the questionnaire. eWOM from rating sites scored second in all categories, and eWOM from Facebook friends scored lowest in all categories. It can therefore be concluded that negative WOM-information can influence consumer purchase decision in different ways, and even though eWOM is widely used it is considered to be less informative and trustworthy than traditional oral WOM.

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Ahlstrand, Einar Vanja, e Kajsa Åkerblom. "“Vem som helst, kan skriva vad som helst” : En kvalitativ studie om recensioners påverkan på konsumenten och informationssökningsprocessen inom hotellbokningar online". Thesis, Södertörns högskola, Turismvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-36427.

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Purpose: The authors have found a common interest to investigate how the use and impact of reviews online can be applied within the subject of tourism. The purpose of the study is to investigate how consumers use reviews in their information search process. The purpose is also to investigate how and if consumers are influenced by online reviews regarding hotel stays. Method: The study is based on a qualitative method in the form of ten semi structured interviews as primary collection. The study has a support from secondary data consisting of a literature review in the chapter of previous research. Theory: The theoretical background is based on three theories. The theories are The PrePurchase-Information process, The Major Influences On Individual Travel Behaviour and the theory From Word-Of-Mouth to Electronic Word-Of-Mouth. Empiricism: The empiricism consists of a presentation of ten semi structured interviews with anonymous respondents regarding their own experiences and beliefs about the topic of the study. The chapter also includes an overview of the previous research about the topic to support and enhance the primary empirical interview material. Findings: The digital society has led to an increased online presence, critical thinking and interest on how consumers travel and what hotels they choose. Impact is constantly present in their contact with reviews and surroundings. The individuals own interpretation and perception of reality is based primarily on how they use and are influenced by reviews. In combination with critical thinking there is an insight that anyone, can write anything.

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Jansson, Christine, e Polina Zakharkina. "Motives behind positive electronic Word-of-Mouth on social networking sites : So, why do you "like" that?" Thesis, Uppsala universitet, Företagsekonomiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202572.

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Consumers are increasingly engaging with brands on social networking sites (SNS) through activities such as sharing, commenting, liking and recommending products or brands to other consumers. These types of recommendations are referred to as electronic word‐of‐mouth (eWOM) and are proven to have a significant influence on consumers’ purchasing decisions. Previous research has investigated motives for traditional WOM and motives for eWOM on opinion platforms. This study proposes that eWOM on SNSs is a combination of traditional WOM and eWOM on opinion platforms. By using a sample of 154 Swedish Facebook users, this study explores why consumers engage in positive eWOM communication on SNSs. This is done by testing 6 validated motives that are identified in previous research in the new context. The resulting analysis suggests that consumers’ need for social interaction and desire to express positive emotions are the primary drivers behind engagement in positive eWOM communication on SNSs. The findings confirm that eWOM on SNSs contains elements of both traditional WOM and eWOM on opinion platforms and should thus be considered as a unique context where eWOM takes place.

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5

Rennison, Robyn. "What you say? Word of mouth within social media". Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/25221.

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This paper extends the understanding of the word of mouth (WOM) concept and its new role within social media and thereafter analysing the impact that electronic WOM (eWOM) has on marketing campaigns. Quantitative descriptive research was employed, using the tweets that were part of the Vodacom Twitter network. This data was used to analyse the differences of activity and sentiment within the tweets. The collection of tweets were then measured against a proxy, Vodacom’s rebranding campaign. The researcher was able to identify the impact of the rebranding campaign on consumers through the changes in the responses before, during and after the campaign. The research found that the rebranding campaign resulted in higher levels of engagement between consumers and the brand. During the rebranding process, negative sentiments were lowered, however the end result of the campaign left consumers with more negativity regarding the branding. The paper advances marketing practitioners understanding of how WOM and social media play a critical role in today’s marketing. Consumers are no longer bystanders in the marketing process and are instead turning to social media as a source of information as well as a platform to communicate their opinions and attitudes. Copyright
Dissertation (MBA)--University of Pretoria, 2011.
Gordon Institute of Business Science (GIBS)
unrestricted

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Podder, Pronab Swarup, e Kaniz Sawda Tanjee. "The Influence of e-WOM through SNS on Brand Perception and Consumer Purchase Intention: Study on Bangladeshi consumers". Thesis, Högskolan i Gävle, Avdelningen för ekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-36215.

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Aim: The aim of the study is to investigate the influence e-WOM through social network sites has on consumers focusing on brand perception and purchase intention. Methodology: A qualitative study was applied with the semi-structured online interview conducted with nine respondents across Bangladesh. The collected primary data were transcribed and thematically analyzed with the reviewed literature. Findings and Conclusion: We conclude that e-WOM through SNS helps consumers to select smartphones and gadgets. Due to paid reviews and negative influencers, trustworthiness is vital on SNS reviews. Also, the recommendation from known sources or personal research increases brand perception. Rather than relying on single reviews on SNS, it is highly recommended to justify the reviews for purchase intention of smartphones or gadgets. Contribution of the Thesis: This study suggests that e-WOM through SNS influences consumers' purchase of smartphones or gadget brands. It is recommended for the managers to determine reviewers on SNS regarding smartphone or gadget brands. Besides, this study exposes the importance of trustworthiness in SNS reviews. Suggestion for the Future Research: We suggest future research on a similar topic using a larger sample size. We also propose a comparative study with two or more countries on similar products to determine differences and results relatively. Besides, this study only focused on smartphones or gadget items; focusing on different products with larger audiences might be done for future research. Furthermore, future research could be done

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7

Jargalsaikhan, Erdenebulgan, e Mohammed Battha. "The affect of eWOM on brand image and purchase intention : A study on the smartphone industry in Sweden". Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-54448.

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Date: 3 June 2021 Level: Bachelor Thesis in Business Administration, 15 cr Institution: School of Business, Society and Engineering, Mälardalen University Authors: Battha Mohammed Jargalsaikhan Erdenebulgan (93/06/10) (99/12/14) Title: The affect of eWOM on the brand image and purchase intention Tutor: David Freund Keywords: Electronic word of mouth (eWOM), word of mouth (WOM), brand image, smartphone Research question: Does eWOM affect a brand image? Purpose: The purpose of this research study is to determine eWOM affects on brand image concerning smartphone industries in Sweden Method: To fulfill the purpose of the research study used quantitative method. The quantitative method is used by applying questionnaires to collect the empirical data to answer the research question. A sample size of 168 respondents was selected and statistical analyses were carried out to show the distribution of the collected data. Conclusion: The study found that there is a strong affect of eWOM on the brand image of the smartphone industry in Sweden. The study concludes that it is important for firms and brands to invest in their technological marketing platforms where they can respond to customer concerns immediately.

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Braunander, Joacim, e Fredrik Olofsson. "Låt inte gästen få sista ordet. : En kvalitativ studie om hur tjänsteföretag inom besöksnäringen arbetar och skulle kunna arbeta med Sociala medier, WOM och eWOM". Thesis, Umeå universitet, Företagsekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102180.

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Internet har utvecklats snabbt de senaste åren och med utvecklingen har sociala medier blivit en stor del av Internet. Sociala medier innebär all form av kommunikation som sker på Internet så som exempelvis Tripadvisor, Facebook, Twitter, Booking.com eller Instagram. Konsumenter som väljer att kommentera upplevelser och produkter på sociala medier ökar. Enligt forskning så litar framtida konsumenter mer på andra konsumenters kommentarer än vad de litar på företagets marknadsföring över deras produkt/tjänst. Kommentarer som skrivs på olika sociala medier lämnas ofta obesvarade av tjänsteföretagen. De kommentarer som lämnas på sociala medier har en stor effekt på framtida konsumenters köpbeslut. Den form av kommunikation som gästerna förmedlar på sociala medier kallas electronic Word-of-mouth eller eWOM. Vilket ledde oss in på att genomföra en studie som undersöker hur tjänsteföretag tar sig an och hur de skulle kunna arbeta med kommunikation genom WOM, eWOM och sociala medier. Vi undersökte detta genom att göra en jämförande studie mellan olika hotell i Umeå. En modell med fyra olika steg skapades för att ta fram en eventuell kommunikationsprocess till tjänsteföretagen. Modellen lägger grund för den undersökning som vi genomför vid insamlandet av data. Undersökningen gjordes som en kvalitativ forskning med ett avsiktligt urval där vi intervjuade en respondent för respektive företag. Undersökningen visade att det finns en skillnad mellan hur och till vilken grad tjänsteföretagen i Umeå använder sig av eWOM och sociala medier i sin kommunikation med konsumenterna Många tjänsteföretag skulle kunna förbättra det operativa arbetet med WOM, eWOM och sociala medier.

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Eriksson, Christian, e Erik Wetterling. "Hur Value Propositions formas genom interaktion mellan aktörer i nätverk : En studie av styrketräningsutövare och kosttillskottsprodukter". Thesis, Uppsala universitet, Företagsekonomiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-219125.

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Idag marknadsförs mängder av produkter vars funktionella värde, av olika anledningar, är svårt för konsumenterna att konkret utvärdera. De Value Propositions som tillverkare och återförsäljare av dessa produkter förmedlar skiljer sig potentiellt från de Value Propositions som konsumenterna faktiskt använder sig av vid sina köpbeslut. Dessa produkters natur medför att konsumenterna tar aktörer, andra än producenterna och återförsäljarna, till sin hjälp för att vidareutveckla ursprungligt Value Proposition. Denna process utgörs av interaktion med exempelvis andra konsumenter i samma fysiska och/eller virtuella sociala nätverk. Nätverket blir då ett system för utformning och vidareutveckling av Value Propositions. Uppsatsen undersöker hur nätverket av och omkring styrketräningsutövare som använder kosttillskottsprodukter, formar de Value Propositions som associeras med produkterna. Studien finner att dessa Value Propositions formas av aktörer andra än producenterna/återförsäljarna via word-of-mouth samt electronic word-of-mouth. Studien identifierar vidare faktorer som påverkar det inflytande aktörerna har i utformningen.

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Wu, Meng. "Data mining cDNA microarray experiment with a GEE approach /". Electronic version (PDF), 2004. http://dl.uncw.edu/etd/2004/wum/mengwu.pdf.

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Youssef, Ahmed H. "ASSESSMENT OF PHOTONIC SWITCHES AS FUTURE REPLACEMENT FOR ELECTRONIC CROSS-CONNECT SWITCHES". International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608526.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
This paper presents the future of optical networking via photonic switches as a potential replacement for the existing electronic cross-connects. Although optical amplifiers are now mainstream and wave division multiplexing (WDM) systems are a commercial reality, the industry’s long-term vision is one of the all-optical network. This will require optical switching equipment such as all-optical or “photonic” cross-connect switches that will provide packet switching at an optical layer. Currently, as voice calls or data traffic are routed throughout Range and commercial networks, the information can travel through many fiber-optic segments which are linked together using electronic cross-connects. However, this electronic portion of the network is the bottleneck that is preventing the ideal network from achieving optimal speeds. Information is converted from light into an electronic signal, routed to the next circuit pathway, then converted back into light as it travels to the next network destination. In an all-optical network, the electronics are removed from the equation, eliminating the need to convert the signals and thereby significantly improving network performance and throughput. Removing the electronics improves network reliability and restoration speeds in the event of an outage, provides greater flexibility in network provisioning, and provides a smooth transition when migrating to future optical transmission technologies. Despite the fact that photonic switching remains uncommercialized, it now seems apparent that the core switches in both the public networks and DoD Range networks of the early 21st century will probably carry ATM cells over a photonic switching fabric.

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Devaney, John F. L. "WDM of solitons in dispersion managed transmission systems". Thesis, Aston University, 1998. http://publications.aston.ac.uk/7977/.

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This thesis investigates the physical behaviour of solitons in wavelength division multiplexed (WDM) systems with dispersion management in a wide range of dispersion regimes. Background material is presented to show how solitons propagate in optical fibres, and key problems associated with real systems are outlined. Problems due to collision induced frequency shifts are calculated using numerical simulation, and these results compared with analytical techniques where possible. Different two-step dispersion regimes, as well as the special cases of uniform and exponentially profiled systems, are identified and investigated. In shallow profile, the constituent second-order dispersions in the system are always close to the average soliton value. It is shown that collision-induced frequency shifts in WDM soliton transmission systems are reduced with increasing dispersion management. New resonances in the collision dynamics are illustrated, due to the relative motion induced by the dispersion map. Consideration of third-order dispersion is shown to modify the effects of collision-induced timing jitter and third-order compensation investigated. In all cases pseudo-phase-matched four-wave mixing was found to be insignificant compared to collision induced frequency shift in causing deterioration of data. It is also demonstrated that all these effects are additive with that of Gordon-Haus jitter.

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Saunier, Paul-Laurent. "Qualité et contrôle dans les services : le cas des services à la personne". Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00824183.

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Les activités de services à la personne incarnent un important potentiel de création d'emplois et de réponse à des besoins sociaux. Elles présentent comme principales caractéristiques une forte dimension relationnelle qui influence leur qualité, ainsi qu'une distance spatiale qui complique le contrôle de cette qualité. L'objectif de cette thèse est d'analyser les pratiques de contrôle de la qualité des organismes offreurs, ainsi que les représentations des différents acteurs en matière de qualité de service.L'approche qualitative retenue donne lieu à la réalisation de deux études empiriques, l'une concernant les services à destination de personnes dépendantes (SAD), l'autre ceux à destination des autres publics (SAP). Au total, 38 entretiens sont réalisés auprès de dirigeants et responsables qualité d'organismes offreurs, 169 avis de bénéficiaires et 318 avis d'intervenants sont collectés sur Internet, ce dispositif étant complété par une phase d'observation participante. Les données recueillies font l'objet d'une analyse de contenu.Ces études permettent d'identifier les critères de qualité perçue des bénéficiaires et des intervenants, trois approches de la qualité des organismes offreurs, sept étapes du processus de production associées aux trois phases du processus de contrôle, les objectifs assignés ainsi que les mécanismes de contrôle mobilisés lors de ces étapes. Les résultats montrent l'influence du régime juridique retenu (prestataire ou mandataire) sur les pratiques de contrôle de la qualité. Ils soulignent également la nécessaire cohérence entre la représentation de la qualité du manager et les mécanismes de contrôle mobilisés pour influencer la qualité.

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Angeletti, Andrea. "Electronic properties of the WO2 (001) polar surface of tungsten trioxide". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23141/.

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Tungsten trioxide WO3 shows promising perspectives in many fields of research. Surface states appear to play a fundamental role on the overall functionality of the material. Experimental evidences showed the capability to consistently obtain meta-stable polar surfaces, characterized by large amount of excess charge on the surface. In this study, we investigate the WO2 terminated polar (001) surface, by density functional theory calculations. Our data suggest a tri-dimensional nature of the excess electrons, delocalized across the entire slab, compared to the usually observed two-dimensional electron gas behavior, in the case of common transitional metal oxide. The material is expected to be able to host excess charge also in localized states (namely polarons). Furthermore, this work also suggests a deep coupling between the antiferroelectric distorsions, the oxygen vacancies at the topmost layer, and the dispersion of the excess charge. Our results, constitute overall solid bases to further investigate these connections and a valid starting point towards the opportunity to tune the electronic properties of the WO3 surface.

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Sharma, Oliver. "Detecting worm mutations using machine learning". Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/469/.

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Worms are malicious programs that spread over the Internet without human intervention. Since worms generally spread faster than humans can respond, the only viable defence is to automate their detection. Network intrusion detection systems typically detect worms by examining packet or flow logs for known signatures. Not only does this approach mean that new worms cannot be detected until the corresponding signatures are created, but that mutations of known worms will remain undetected because each mutation will usually have a different signature. The intuitive and seemingly most effective solution is to write more generic signatures, but this has been found to increase false alarm rates and is thus impractical. This dissertation investigates the feasibility of using machine learning to automatically detect mutations of known worms. First, it investigates whether Support Vector Machines can detect mutations of known worms. Support Vector Machines have been shown to be well suited to pattern recognition tasks such as text categorisation and hand-written digit recognition. Since detecting worms is effectively a pattern recognition problem, this work investigates how well Support Vector Machines perform at this task. The second part of this dissertation compares Support Vector Machines to other machine learning techniques in detecting worm mutations. Gaussian Processes, unlike Support Vector Machines, automatically return confidence values as part of their result. Since confidence values can be used to reduce false alarm rates, this dissertation determines how Gaussian Process compare to Support Vector Machines in terms of detection accuracy. For further comparison, this work also compares Support Vector Machines to K-nearest neighbours, known for its simplicity and solid results in other domains. The third part of this dissertation investigates the automatic generation of training data. Classifier accuracy depends on good quality training data -- the wider the training data spectrum, the higher the classifier's accuracy. This dissertation describes the design and implementation of a worm mutation generator whose output is fed to the machine learning techniques as training data. This dissertation then evaluates whether the training data can be used to train classifiers of sufficiently high quality to detect worm mutations. The findings of this work demonstrate that Support Vector Machines can be used to detect worm mutations, and that the optimal configuration for detection of worm mutations is to use a linear kernel with unnormalised bi-gram frequency counts. Moreover, the results show that Gaussian Processes and Support Vector Machines exhibit similar accuracy on average in detecting worm mutations, while K-nearest neighbours consistently produces lower quality predictions. The generated worm mutations are shown to be of sufficiently high quality to serve as training data. Combined, the results demonstrate that machine learning is capable of accurately detecting mutations of known worms.

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Bhamber, Ranjeet S. "Numerical modelling of advanced modulation formats and WDM transmission". Thesis, Aston University, 2006. http://publications.aston.ac.uk/8104/.

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This thesis presents a theoretical investigation of the application of advanced modelling formats in high-speed fibre lightwave systems. The first part of this work focuses on numerical optimisation of dense wavelength division multiplexing (DWDM) system design. We employ advanced spectral domain filtering techniques and carrier pulse reshaping. We then apply these optimisation methods to investigate spectral and temporal domain characteristics of advanced modulation formats in fibre optic telecommunication systems. Next we investigate numerical methods used in detecting and measuring the system performance of advanced modulation formats. We then numerically study the combination of return-to-zero differential phase-shift keying (RZ-DPSK) with advanced photonic devices. Finally we analyse the dispersion management of Nx40 Gbit/s RZ-DPSK transmission applied to a commercial terrestrial lightwave system.

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Hammarling, Krister. "Printed electronics : Implementation of WORM memory in a RF-antitheft system". Thesis, Mid Sweden University, Department of Information Technology and Media, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-11644.

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Current printable memory technology are not suited for mass produc‐tion. With new inexpensive printed memory, it will be possible to manufacture cheap surveillance tags that are capable to tell the user if something has happened within a timeline. This project is within the ITC FrameProgram 7 founded project PriMeBits. The goal is to imple‐ment a write once read many memory (WORM) onto an RF‐tag together with a sensor that can sense wetness, which can be detected by EAS antitheft systems. Pre researches have been done in the fields printed capacitance, coils and WORMs, all printed with silver ink. Before implementation of a WORM onto a tag simulations and laboratory tests with adjustable resistances were made. Two different circuit models are simulated and tested. When connected to a tag and the WORM is un‐programmed, the EAS system should not trigger an alarm. But if the WORM is programmed by the sensor, the alarm should trigger. Results show that capacitances and WORMs are printable with this technique but coils are not due to high inner resistance. The simulations show that a tag built as an LCCR‐circuit is the best choice. This is also confirmed with tests done with real resistors. With WORMs connected to a tag the results show that approximately 70% of them work as intended, this is because the WORMs as of now are not completely developed. The conclusion of this project is that it is possible to implement a WORM onto a tag with further research, to make an inexpensive surveillance tag.

PriMeBits

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Nahas, Mousaab. "Investigation of different techniques to upgrade legacy WDM communication systems". Thesis, Aston University, 2006. http://publications.aston.ac.uk/15361/.

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This thesis presents experimental investigation of different effects/techniques that can be used to upgrade legacy WDM communication systems. The main issue in upgrading legacy systems is that the fundamental setup, including components settings such as EDFA gains, does not need to be altered thus the improvement must be carried out at the network terminal. A general introduction to optical fibre communications is given at the beginning, including optical communication components and system impairments. Experimental techniques for performing laboratory optical transmission experiments are presented before the experimental work of this thesis. These techniques include optical transmitter and receiver designs as well as the design and operation of the recirculating loop. The main experimental work includes three different studies. The first study involves a development of line monitoring equipment that can be reliably used to monitor the performance of optically amplified long-haul undersea systems. This equipment can provide instant finding of the fault locations along the legacy communication link which in tum enables rapid repair execution to be performed hence upgrading the legacy system. The second study investigates the effect of changing the number of transmitted 1s and Os on the performance of WDM system. This effect can, in reality, be seen in some coding systems, e.g. forward-error correction (FEC) technique, where the proportion of the 1s and Os are changed at the transmitter by adding extra bits to the original bit sequence. The final study presents transmission results after all-optical format conversion from NRZ to CSRZ and from RZ to CSRZ using semiconductor optical amplifier in nonlinear optical loop mirror (SOA-NOLM). This study is mainly based on the fact that the use of all-optical processing, including format conversion, has become attractive for the future data networks that are proposed to be all-optical. The feasibility of the SOA-NOLM device for converting single and WDM signals is described. The optical conversion bandwidth and its limitations for WDM conversion are also investigated. All studies of this thesis employ 10Gbit/s single or WDM signals being transmitted over dispersion managed fibre span in the recirculating loop. The fibre span is composed of single-mode fibres (SMF) whose losses and dispersion are compensated using erbium-doped fibre amplifiers (EDFAs) and dispersion compensating fibres (DCFs), respectively. Different configurations of the fibre span are presented in different parts.

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19

Muhammad, Ajmal. "Connections Provisioning Strategies for dynamic WDM networks". Licentiate thesis, Linköpings universitet, Informationskodning, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-84795.

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The size, complexity, and the amount of traffic generation of optical communication networks have dramatically increased over the last decades. Exciting technologies, namely, optical amplifiers, wavelength division multiplexing (WDM) and optical filters have been included in optical networks, in order to fulfill end users appetite for bandwidth. However, the users high bandwidth demand will further increase with time, as emerging on-demand bandwidth intensive applications are starting to dominate the networks. Applications such as interactive video, ultra-high definition TV, backup storage, grid computing, e-science, e-health to mention a few, are becoming increasingly attractive and important for the community. Given the high bandwidth requirements and strict service level specifications (SLSs) of such applications, WDM networks equipped with agile devices, such as reconfigurable optical add-drop multiplexers and tunable transceivers integrated with G-MPLS/ASON control-plane technology are advocated as a natural choice for their implementation. SLSs are metrics of a service level agreement (SLA), which is a contract between a customer and network operator. Apart from other candidate parameters, the set-up delay tolerance and connection holding-time have been defined as metrics of SLA. This work addresses the network connections provisioning problem for the above mentioned demanding applications, by exploiting the time dimension of connections request. The problem is investigated for dynamic networks comprising ideal and nonideal components in their physical layer, and for applications with differentiated set-up delay tolerance and quality of signal requirements. Various strategies for different scenarios are proposed, each strategy combining in a different way the concept of both set-up delay tolerance and connection holding-time awareness. The objectives of all these strategies are to enhance the network connections provisioning capability and to fulfill customers demand, by utilizing the network resources efficiently.

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20

Hassan, Ali. "Particle swarm optimization for routing and wavelength assignment in next generation WDM networks". Thesis, Queen Mary, University of London, 2010. http://qmro.qmul.ac.uk/xmlui/handle/123456789/533.

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All-optical Wave Division Multiplexed (WDM) networking is a promising technology for long-haul backbone and large metropolitan optical networks in order to meet the non-diminishing bandwidth demands of future applications and services. Examples could include archival and recovery of data to/from Storage Area Networks (i.e. for banks), High bandwidth medical imaging (for remote operations), High Definition (HD) digital broadcast and streaming over the Internet, distributed orchestrated computing, and peak-demand short-term connectivity for Access Network providers and wireless network operators for backhaul surges. One desirable feature is fast and automatic provisioning. Connection (lightpath) provisioning in optically switched networks requires both route computation and a single wavelength to be assigned for the lightpath. This is called Routing and Wavelength Assignment (RWA). RWA can be classified as static RWA and dynamic RWA. Static RWA is an NP-hard (non-polynomial time hard) optimisation task. Dynamic RWA is even more challenging as connection requests arrive dynamically, on-the-fly and have random connection holding times. Traditionally, global-optimum mathematical search schemes like integer linear programming and graph colouring are used to find an optimal solution for NP-hard problems. However such schemes become unusable for connection provisioning in a dynamic environment, due to the computational complexity and time required to undertake the search. To perform dynamic provisioning, different heuristic and stochastic techniques are used. Particle Swarm Optimisation (PSO) is a population-based global optimisation scheme that belongs to the class of evolutionary search algorithms and has successfully been used to solve many NP-hard optimisation problems in both static and dynamic environments. In this thesis, a novel PSO based scheme is proposed to solve the static RWA case, which can achieve optimal/near-optimal solution. In order to reduce the risk of premature convergence of the swarm and to avoid selecting local optima, a search scheme is proposed to solve the static RWA, based on the position of swarm‘s global best particle and personal best position of each particle. To solve dynamic RWA problem, a PSO based scheme is proposed which can provision a connection within a fraction of a second. This feature is crucial to provisioning services like bandwidth on demand connectivity. To improve the convergence speed of the swarm towards an optimal/near-optimal solution, a novel chaotic factor is introduced into the PSO algorithm, i.e. CPSO, which helps the swarm reach a relatively good solution in fewer iterations. Experimental results for PSO/CPSO based dynamic RWA algorithms show that the proposed schemes perform better compared to other evolutionary techniques like genetic algorithms, ant colony optimization. This is both in terms of quality of solution and computation time. The proposed schemes also show significant improvements in blocking probability performance compared to traditional dynamic RWA schemes like SP-FF and SP-MU algorithms.

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21

Alegria, Carlos Feio Gama. "All-fibre devices for WDM optical communications". Thesis, University of Southampton, 2001. https://eprints.soton.ac.uk/30238/.

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This thesis is concerned with the study of two key technologies for enabling wavelength division multiplexed optical communication systems. The first is gain equalisation of the erbium-doped fibre amplifier and the second is the routing of optical channels through the network by means of all-fibre add-drop multiplexer configurations. A laser beam is scanned along the coupler length inducing a local perturbation to the coupler eigenmodes. Asymmetric and symmetric perturbations can give accurate mapping of power-evolution and coupler waist shape.

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22

Khaleghi, Farideh. "Erbium-doped fiber amplifier applications in WDM transport systems and networks". Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10194.

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New expressions are derived for wavelength-dependent gain variations of the EDFA due to changes in the pump power, total input power, and the power distribution among different wavelength channels in a wavelength-division multiplexing (WDM) system. A simple method is proposed to compensate for the changes in the amplifier gain spectrum. This method is based on adjusting the pump power. Two different novel gain equalization techniques are presented. A tunable coherent optical transversal filter is designed as a gain equalizer. The filter operation is based on coherently combining the tapped signals. It is shown that, although the N tapped signals after being weighted according to the filter parameters are recombined by a tree of 2 x 2 couplers, the coupling loss experienced at the output is much less than the noncoherent coupling loss (10log(N)). For a multi-wavelength input, the spectrum of the amplifier output power is evaluated before and after the equalizer, using the numerical full spectrum model of the amplifier. The impact of the laser phase noise on the performance of this equalizer is studied. Another gain equalization technique is presented where high- and moderate-inversion EDFAs are used alternatively in order to equalize both signal power and signal-to-noise ratio (SNR) of multiple wavelength channels in WDM transmission systems. This technique is based on the fact that the gain slope is a function of the inversion level in amplifiers. This is confirmed experimentally. The performance of the equalized WDM system is examined by a numerical analysis based on the full spectrum model of the amplifier. The interferometric conversion of the phase-to-intensity noise is studied. The probability density function (pdf) of the intensity noise at the output of a multi-tap filter is derived. The degradation of the filter response is evaluated. The power penalty due to this noise is derived for amplitude modulated signals modulated using different bit rates. The power penalty due to interferometric noise caused by multiple reflections is also derived. A novel bidirectional EDFA configuration is proposed where the power penalty associated with the amplifier due to both the signal-spontaneous noise and the interferometric noise is substantially reduced. The experimental results are presented where a gain of 36 dB is achieved, and a 2.5 Gb/s bidirectional transmission over 300 km is realized. The power penalty is as low as 0.5 dB. Application of EDFA in an optical network is presented. The multi-access scheme in this local network is code-division multiple access (CDMA). A new correlator receiver architecture for noncoherent optical CDMA networks is proposed based on a modified version of unipolar-bipolar correlation functions for known bipolar codes. These functions are studied. Average bit error rate (BER) performance is evaluated for this architecture. The results indicate that bipolar capacity can be achieved by this architecture.

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23

Kan, Daniel Dao-Jun 1979. "Design of survivable IP-over-WDM networks : providing protection and restoration at the electronic layer". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87353.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references (leaves 107-109).
by Daniel Dao-Jun Kan.
S.M.

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24

Yu, Shen. "Performance Evaluation of Optimized Resource Allocations in WDM Networks under Dynamic Traffic". Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28825.

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Wavelength-routed Wavelength-Division Multiplexing (WDM) optical networks are developed to meet the increasing bandwidth demands of recent Internet applications. In the real world, the traffic demands are always dynamic. The question of how to optimally allocate the network resources in a wavelength-routed WDM optical network to satisfy dynamic demands is called the dynamic routing and wavelength assignment (RWA) problem. In the literature, many schemes are proposed to address this problem. In this thesis, we study how to improve the performance of certain dynamic RWA schemes by using the distribution of the dynamic demands, which is assumed to be known in advance. With the knowledge of the network topology and distribution of the dynamic traffic, we can use an existing mathematical approach to calculate, for each link, a cost value called Multiplier Guide. This link cost is obtained by considering a static RWA optimization problem having the average traffic demands of the dynamic RWA problem that we want to solve. When this link cost is used instead of the hop count to compute minimal cost paths, the performance of some dynamic RWA schemes can be improved, as shown by our simulation studies. In the thesis, we review and implement several existing dynamic RWA schemes; we also propose and implement some new dynamic RWA schemes. We apply the Multiplier Guide to all these schemes and run simulations to test whether their performance is improved. As a necessary part of these schemes, we implement many different network routing algorithms including single shortest path routing, link-disjoint paths routing and k-shortest paths algorithm. To simulate the schemes that search an RWA solution exhaustively with or without the wavelength conversion assumption, we implement two auxiliary graphs and two algorithms associated with the graphs, respectively. We also implement the schemes that use link utilization obtained from simulations or measurements to decide link cost; and we compare them with the schemes that use the Multiplier Guide as link cost. We find that, when the Multiplier Guide is applied to the dynamic RWA schemes that use pre-constructed paths, their performance is improved. However, when the Multiplier Guide is applied to the schemes that search an RWA solution exhaustively, their performance is not improved.

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25

Eshoul, AbdElhamid Eswei. "Algorithms for survivable routing and wavelength assignment in WDM wavelength-routed mesh networks". Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/29349.

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Due to the huge amount of data that can be lost and the large number of users that can be disrupted during the times of failure in wavelength division multiplexing (WDM) optical networks, reliable optical layer that can quickly and efficiently respond to failures such as fiber cuts is a critical issue to users and service providers. The major challenge in survivable mesh networks is the design of resource allocation algorithms that allocate network resources efficiently while at the same time are able to recover from a failure quickly. This issue is particularly more challenging in optical networks operating under wavelength continuity constraint, where the same wavelength must be assigned on all links in the selected path. This thesis presents a number of schemes to solve the problem of survivable routing and wavelength assignment (RWA) in wavelength-routed WDM networks. The focus is on developing algorithms for survivable RWA in mesh networks that address both resource efficiency and restoration speed under static and dynamic traffic environments. Two different approaches (diverse routing and p-cycles) are pursued to solve the problem of survivable RWA. Their performances and complexities are also compared. Under static traffic, new algorithms have been developed to formulate the RWA as an Integer Linear programming problem using both diverse routing and p-cycles. Under dynamic traffic, new heuristic algorithms are developed to solve the survivable RWA using both approaches and their performances are evaluated and compared using simulations.

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26

Sandes, Fábio Shimabukuro. "Um estudo empírico sobre o uso do boca a boca gerado na internet como comunicação com o cliente". reponame:Repositório Institucional do FGV, 2010. http://hdl.handle.net/10438/4744.

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Made available in DSpace on 2010-04-20T20:14:43Z (GMT). No. of bitstreams: 1 61080100031.PDF: 7443816 bytes, checksum: a82ca7f98a374b3f75cdb221b7fb942b (MD5) Previous issue date: 2010-02-22T00:00:00Z
O impacto do boca a boca na Imagem da Marca e no julgamento de produtos (bens e serviços) tem sido estudado há tempos na disciplina de comportamento do consumidor. Com o crescimento da internet como mídia social e meio de comunicação entre consumidores e empresas, o boca a boca ganhou força junto a profissionais e pesquisadores de Marketing. Uma revisão da literatura permitiu traçar um paralelo entre o boca a boca tradicional e o eletrônico. É preciso compreender cientificamente a influência do boca a boca eletrônico no comportamento do consumidor. Para isto, foram realizados dois estudos nesta dissertação, sendo o primeiro um estudo exploratório a partir da realização de entrevistas e aplicação de questionários a consumidores, profissionais de Marketing e especialistas do assunto com o intuito de levantar percepções gerais sobre o tema. Para avaliar estatisticamente as hipóteses propostas nesta dissertação, o segundo estudo foi a realização de um experimento com 168 estudantes, contando com cinco cenários e três tipos de produtos (Vestuário, Cosméticos e Lojas Online). A variável independente foi o Comentário Postado pelo consumidor. Duas foram as variáveis dependentes: Imagem da Marca e Intenção de Compra dela. Para a mensuração da Imagem da Marca se utilizou a escala de Personalidade de Marca de Aaker (1997). No tocante à Intenção de Compra, um concurso foi elaborado para os sujeitos. No início e no final da coleta de dados, os participantes escolhiam as empresas das quais ganhariam um prêmio (vale compra), caso fossem os vencedores. Mediu-se a Intenção de Compra em função da escolha dos consumidores antes e depois do estímulo, sendo comparados, ainda, os resultados dos diferentes cenários. Constatou-se que os comentários negativos e positivos que os consumidores postam na internet têm um impacto significante na Imagem da Marca para outros consumidores nos produtos Vestuário e Loja Online. Mas não foram percebidos impactos destes comentários na Imagem da Marca no produto Cosmético e na Intenção de Compra dos outros consumidores nos três tipos de produtos testados. O Gerenciamento dos Comentários negativos (resposta da empresa a comentário postado pelo consumidor) apresentou uma redução no impacto do comentário na Imagem da Marca para os outros consumidores no produto Loja Online. Contudo, os tons alinhados com Foco Regulatório do consumidor nas respostas das empresas não provocaram diferenças significativas, contra indicando essa concepção teórica como meio de aprimorar os resultados do Gerenciamento dos Comentários. Várias implicações científicas e profissionais interessantes decorrem da pesquisa. Para o praticante, se viu que a internet 2.0 é uma mídia a ser considerada no esforço de comunicação da empresa e que ela deve ser considerada como um canal de comunicação bidirecional.
The impact of Word of Mouth Communication on Brand Image and the evaluation of products (goods and services) has been studied for some time in the discipline of consumer behavior. With the growth of the Internet as a social media and as a means of communication between consumers and enterprises, Word of Mouth has gained strength with Marketing professionals and researchers. A review of the literature draws a parallel between traditional Word of Mouth and its electronic version. It is essential to understand scientifically the influence of Electronic Word of Mouth on consumer behavior. In order to do this, two main studies were made: the first one was an exploratory stage conducted with interviews and questionnaires applied to consumers, marketers, and experts on the subject in order to raise general perceptions on the issue. The second study aims to evaluate statistically the hypotheses proposed in this work and involves an experiment applied to 168 students, considering five scenarios and three types of products (clothing, cosmetics and Online Stores). The independent variable was the Comment Posted by the consumer on the internet. Two were the dependent variables: Brand Image and Purchase Intention. To measure Brand Image, the scale "The Brand Personality" by Aaker (1997) was used. To measure Purchase Intention subjects participated in a contest where they chose, at the beginning and end of data collection, the companies from which they would gain a gift certificate, if they won the contest. Purchase Intention was measured depending on the choice of consumers before and after the stimulus, and compared also the results of different scenarios. It was found that the positive and negative comments that consumers posted on the internet have a significant impact on Brand Image for other consumers of products in Clothing and Online stores. However, there was no perceived impact based on these comments regarding Cosmetic products. No impact was found on other consumers' Purchase Intention. Management of Negative Comments (company's response to comments posted by the consumer on the internet) decreased the negative impact of comments on other consumer's Brand Image on product Online Store and the use of Regulatory Focus Theory on companies' responses did not cause significant differences, counter indicating this theoretical concept as a mean to improve the results of managing the comments posted by the consumer on the internet. Several implications of scientific and professional interest arise from this research. For a Marketing professional, it is evident that internet 2.0 should be considered in the media plan of a company and that it should be treated as a two-way communication channel with consumers.

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27

Vieira, Manuel Augusto. "Three transducers for one photodetector: essays for optical communications". Doctoral thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8206.

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Dissertation presented to obtain the PhD degree in Electrical and Computer Engineering - Electronics
Optical processing devices based on a- SiC:H multilayer architectures are expected to become reconfigurable to perform WDM optoelectronic logic functions and provide as well complex photonic functions such as signal amplification and switching. This thesis, entitled ”Three Transducers for One Photodetector: essays for optical communications”, reports the main work areas to design, control, validate and evaluate the research of a voltage-controllable wavelength selective optical switching based on shifting between positive and negative electrically bias and a photodetector, which enables the filtering function with the detector itself and has the potential to be rapidly optically biasing tuned: System Architecture – In this work area it is defined the basic requirements of the device: light-to-dark sensitivity, colour recognition, selective optical and electrical output response, amplification and opto-electronic conversion to transmit, receive, and/or process intelligence(data).The output multiplexed signals should have a strong nonlinear dependence on the light absorption profile, i.e., on the incident light wavelength, bit rate and intensity under unbalanced light generation of carriers. Experimental Design – This test activities work area allows the evaluation of the results. Multiple monochromatic pulsed communication channels were transmitted together, each one with a specific bit sequence. The combined optical signal was analyzed by reading out, under different applied voltages and optical bias, the generated photocurrent across the device. Depending on the wavelength of the external background and irradiation side, it acts either as a short- or a long- pass band filter or as a band-stop filter Optoelectronic Algorithm Interface – To help improve our understanding of the output multiplexed signal, computer models of monolithic photodetectors are developed. Following control theoretic methods we derive state-space representation and an equivalent circuit optoelectronic simulator. We validate each model and calibrate the spectral gain model by background–probe experiments and truth tables lookup that perform 8-to-1 multiplexer (MUX) and 1-to-8 demultiplexer (DEMUX) functions. Applications – The purpose of this work area is to present a new optical logic architecture that offers considerable improvements in reconfigurability. Tunable WDM converters based on amorphous SiC multilayer photonic active filters are used to build blocks to perform standard digital system operations. The transducers combine the simultaneous demultiplexing operation with the photodetection and self amplification. They are optimized for provide the high-sensitivity needed for low-light applications, such as medicine, lighting, sensing and measurement, and manufacturing. The migration to next generation packet based networks can be much easier and smoother than previously thought, using the emerging a-Si solutions and its integration with plastic optical fiber. It will push the limits of functionality, cost/performance and integration level.

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Rosén, Anders. "Embedded Communication Channel for Node Communication in WDM Networks". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209167.

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Optical Transport Network is a set of Optical Network Elements (NE) connected by optical fiber links able to provide support for optical networking using Wavelength-Division Multiplexing (WDM). In order to be able to introduce link-level applications that require NE-to-NE communication in a packet-optical network, an embedded communication channel is needed. Examples of such applications are dual-ended protection, remote configurationand path trace. By implementing a NE-to-NE communication channel, the exchange of commands and information will allow for implementation of applications that will increase the data link stability in the network. The purpose of this work has been to prove the feasibility of such a channel. This thesis discusses the possibilities of implementing such a channel adjusted to Transmode's layer 1 products without causing disturbance inthe regular traffic or affecting any existing embedded communication. It also proves the channels function in a proof-of-concept manner by demonstrating a simple Path trace application run upon an implementation of the channel on hardware. The chosen solution is an Embedded Communication Channel driver intended to provide termination points for an Embedded Communication Channel (ECC), supervising the connectivity of the channel and relay messages to applications. This thesis project has been carried out at Infinera Corporation (earlier Transmode Systems AB) during summer/autumn 2015.

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Omella, Cancer Mireia. "New generation FTTH ONU and OLT design for upstream transmission in WDM PON including optimized combination of electronics and optics". Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/109041.

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This research is developed in the context of the Next Generation of Passive Optical Networks (NG-PON) for Fibre to the Home (FTTH) network. In this thesis, several techniques are proposed in order to increase the network capacity, dealing with the main optical impairments present in PON with minimum infrastructure, and with the goals of wavelength transparency and cost effectiveness. The main issues in this work are the photodetection process over chromatic dispersion (CD) and ASE noise impairments, the mitigation strategies for Rayleigh Backscattering (RB) effect and the WDM-PON RSOA-based ONUs, with their limitations of bandwidth and chirp. Regarding photodetection, a novel module which performs the mathematical function SQRT has demonstrated its linearizing capability at partially compensating the square-law of the photon to electron conversion process after reception. Improvements in RoF systems in terms of harmonics level reduction and in digital transmissions with linear FFE equalizers have been achieved. Also, the complexity requirements in MLSE receivers are reduced after the SQRT module. This module has been implemented electronically, first, by using the intrinsic non-linearity of the schottky diodes, on a microstrip circuit. After that, a MMIC chip has been designed and experimentally tested. But the SQRT module is also useful for other applications as downstream cancellation in the upstream signal in bidirectional transmissions, and to reduce the amplitude differences of the different packets in burst mode receivers, relaxing the adjustment requirements for the following limiting amplifiers. The statistics of the received signals in optically amplified (ASE dominant) systems have been also studied. The optimum function, capable of recovering the Gaussian distribution after detection, has been obtained. For systems working at FEC limit, like with MLSE, the improvement over SQRT is small, validating the good performance of the SQRT module. RB effect has been mitigated by using wavelength shifting at the ONU premises. Several wavelength shifter devices have been proposed for the first time, based in 2 and 3 arms capable of translating (in several GHz) the wavelength that comes from the OLT to avoid the overlap between the upstream signal and the RB, while maintaining the signal in the same AWG channel. These devices are less complex than the recently proposed 4-arm structures and require simpler signals than the sawtooth that is necessary for a 1-arm phase modulator. Experimental validation of the WS technique for RB mitigation has been performed, first with a commercial dual arm MZM and after by using a RSOA with a low duty square signal with improvements of 5 to 7dB in tolerance to RB. The new standards that have just been approved (XG-PON, 10G-EPON) propose the upgrading of the network towards symmetrical 10G/10G operation. However, RSOA’s bandwidth and chirp still limit the performance at these bit rates. The first 10Gb/s transmission in real time and with low BER (10-9) using a RSOA as an intensity modulator has been reported by using some of the techniques presented in this thesis: duobinary transmission and detuned optical filtering plus DFE-FFE equalization. Other techniques proposed and experimentally tested are the phase adjustment with a programmable optical filter and the direct detection together with MLSE equalization.
Aquest treball de recerca està desenvolupat en el context de la nova generació de xarxes òptiques passives (NG-PON) de fibra fins a la llar (Fibre to the Home (FTTH)). En aquesta tesi, s’han proposat diverses tècniques que permeten augmentar la capacitat de la xarxa, tractant les principals degradacions presents en les xarxes PON amb la mínima infrestuctura, amb els objectius de mínim cost i transparència front a la longitud d’ona triada per a la transmissió. Els principals temes d’aquest treball són el procés de fotodetecció després d’una transmissió amb dispersió cromàtica (CD) i soroll d’emissió espontània (ASE), les estratègies per combatre l’efecte de Rayleigh Backscattering (RB) en la trasmissió bidireccional amb la mateixa longitud d’ona i les xarxes PON basades en unitats d’usuari (ONU) que utilitzen l’ amplificador semiconductor reflexiu (RSOA) com a transmissor, amb les seves limitacions d’ample de banda i chirp. Pel que fa a la fotodetecció, un dispositiu novedós que realitza la funció matemàtica arrel quadrada (SQRT) ha demostrat la seva capacitat de linearització al compensar parcialment la funció quadrada del procés de conversió de fotó a electró després de recepció. S’ha aconsegit millorar les prestacions en xarxes de ràdio sobre fibra en termes de reducció del nivel d’harmònics i també en transmissió de senyals digitals amb equalitzadors electrònics lineals. La complexitat de l’ equalitzador de màxima verosimilitud, o MLSE, es redueix si s’utilitza el mòdul SQRT. Aquest dispositiu s’ha implementat electrònicament en un circuit microstrip amb dos diodes schottky i també en un xip MMIC . El bloc SQRT també és útil per aplicacions de cancel•lació del senyal de baixada present en el senyal de pujada en les transmissions bidireccionals i per igualar l’amplitud dels paquets en senyals que es reben a ràfegues (burst mode). L’estadística del senyal rebut en sistemes amplificats òpticament (on domina el soroll ASE) també ha estat estudiat. La funció òptima, capaç de recuperar la distribució estadistica Gaussiana després de detecció, ha estat obtinguda. Per sistemes que treballen amb un nivell de errors en el límit FEC, com el MLSE, la millora de la funció òptima és molt petita front la SQRT, demostrant el bon funcionament del mòdul SQRT. L’efecte de RB s’ha minimitzat utilitzant la tècnica de desplaçar la longitud d’ona del senyal de baixada a la ONU. S’han disenyat diversos dispositius electro-òptics capaços de realitzar aquest desplaçament, utilitzant unes configuracions novedoses basades en 2 i 3 branques. L’efecte RB és redueix evitant el sol•lapament espectral però mantenint la longitud d’ona dins el mateix canal del AWG. Aquests dispositius són més senzills que les recentment proposades estructures basades en 4 branques i requereixen senyals més simples que el dent de serra necessari per al modulador de fase d’una branca. La tècnica WS s’ha validat experimentalment usant un MZM comercial i també usant un RSOA, aconseguint-se unes millores de 5 a 7 dB en tolerància a RB. Els nous estàndards que han estat recentment aprovats (XG-PON, 10G-EPON) proposen l’evolució de la xarxa passiva cap a la transmissió simètrica a 10Gb/s. La realitat és, però, que l’ample de banda i el chirp limiten la utilització de RSOAs a aquesta velocitat. La primera transmissió a 10Gb/s en temps real amb baixa tasa d’errors (BER=10-9) usant el RSOA com a modulador d’intensitat a la ONU ha estat presentat utilitzant les tècniques explicades en aquesta tesi: modulació duobinaria i filtrat òptic desplaçat amb equalització electrònica (DFE-FFE). Altres mètodes utilitzats han estat l’adjust de la fase amb un filtre òptic programable i el MLSE.

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Wakolbinger, Tina, Fuminori Toyasaki, Thomas Nowak e Anna Nagurney. "When and for whom would e-waste be a treasure trove? Insights from a network equilibrium model of e-waste flows". Elsevier, 2014. http://dx.doi.org/10.1016/j.ijpe.2014.04.025.

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Electrical and electronic equipment waste (e-waste) is growing fast. Due to its potential economic value as well as its possible negative impacts on the environment, tracing e-waste flow is a major concern for stakeholders of e-waste management. Especially, whether or not adequate amounts of electrical and electronic equipment waste (WEEE) flow into the designed recycling systems is a fundamental issue for sustainable operations. In this paper, we analyze how technical, market, and legislative factors influence the total amount of e-waste that is collected, recycled, exported and (legally and illegally) disposed off. We formulate the e-waste network flow model as a variational inequality problem. The results of the numerical examples highlight the importance of considering the interaction between the supply and the demand side for precious materials in policy-decisions. Low collection rates of e-waste lead to low profits for stakeholders and make it difficult to establish sustainable recycling operations. Increasing WEEE collection rates increases recyclers' profits; however, it only increases smelters' profits up to a certain limit, after which smelters cannot benefit further due to limited demand for precious materials. Furthermore, the results emphasize the importance of establishing international control regimes for WEEE flows and reveal possible negative consequences of the recent trend of dematerialization. More precisely, product dematerialization tends to decrease recyles' and smelters' profits as well as to increase the outflow of e-waste from the designated recycling system. (authors' abstract)

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Michit, Nicolas. "Switch optique pour la conception de liens WDM rapides en photonique sur silicium". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI033.

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La photonique sur silicium est une solution de remplacement de l’électronique pour les communications demandant des débits extrêmement élevés, intégré avec une haute densité au sein des serveurs, des cartes voire des puces. Pour atteindre de hauts débits (400G, 800G et au-delà), il est intéressant de multiplexer l’information et désagréger les ressources. Cela amène la nécessité de penser des switches capables de gérer de hauts débits et un grand nombre de ports. Dans un premier temps, le choix d’utiliser des liens à base d’anneaux a été justifié notamment en termes de compacité, de flexibilité du réseau qu’ils apportent et de faibles pertes optiques. Ces structures résonantes sont cependant très sensibles et il est important de bien comprendre les phénomènes physiques en jeu. Nous décrivons alors plusieurs modèles de résonance de l’anneau pour ensuite créer un modèle à la fois solvable analytiquement et suffisamment précis pour rendre compte des phénomènes mis en jeu. La validation de ce modèle est réalisée à l’aide de plusieurs tests faisant intervenir l’optique et l’électrique. Ce travail a permis de mieux appréhender l’anneau et ses paramètres constitutifs pour parvenir à minimiser son impact sur un lien WDM. Ensuite, nous avons soumis des idées d’améliorations possibles de ces résonateurs pour pallier à leurs défauts. Ainsi, des disques et des résonateurs utilisant la plateforme en nitrure de silicium ont été simulés, fabriquées puis testés pour finalement les comparer aux résonateurs en anneaux de référence. L’une de ces améliorations est topologique, il s’agit de cascader plusieurs résonateurs pour modifier la résonance finale. Cette modification topologique implique des modifications de l’architecture qui n’est pas forcément adaptée. Une réflexion sur les architectures WDM basées sur des simples et doubles anneaux est alors présentée. Pour limiter les diaphonies thermiques, des commutations groupées par longueur d’onde sont proposées tout en garantissant une table de vérité simple d’usage. La manière de piloter chaque anneau est très importante dans les switches et nous avons démontré un moyen transparent et non invasif de parvenir à faire la détection lumineuse nécessaire à une boucle de rétroaction. Enfin, nous proposons une réponse à la question de la taille maximale d’un switch avec des anneaux. A partir d’hypothèses maitrisées, nous estimons le cout final d’une architecture WDM en fonction du débit, du nombre de ports et de liens WDM. Ces résultats viennent ensuite confirmer ou contredire les hypothèses prises en compte pour l’élaboration de l’architecture du switch
Silicon photonics stands as a promising solution to replace copper interconnections for communication requirements highly integrated inside data centers, inter and intra chip links. To achieve high data rate, one can use multiplexing on optical links combined with disaggregated resources. In such architectures, an optical switch being able to cope with high size and data rate is a core element to be designed. In this study, we focused on intrachip interconnections on a photonic interposer, based on wavelength multiplexed links around the 1310nm communication channel. Integration of laser sources, modulation of the data and reception of the signal is not addressed here. Our goal is the optical switching. At first, the choice to use ring resonators based links has been justified in terms of compactness, network flexibility and low optical losses. Those structures are though very sensitive to environment and geometry fluctuations: it is important to understand well physical effects at stake. We thus describe different ring resonance models to then create a model both analytic and enough accurate to describe peak shifts. The validation of this model is performed with optical and electrical tests. This work allowed a better understanding of the ring parameters in order to minimize its impact on a WDM link. We then propose ideas of possible improvements for those resonators. Disks and resonators using the silicon nitride layer have been simulated, fabricated and tested to compare their performances to the reference design. One of those improvements is topologic. One resonator is replaced by two coupled rings, to achieve a higher order of resonance. Since most of the switching architecture are not adapted to the use of double rings, we developed a new approach on that topic. To limit thermal crosstalk in WDM switches while keeping low footprint, resonators are grouped with respect to their wavelength. The scalability is preserved with a truth table kept to a fair level of simplicity for any number of wavelength multiplexed. The way to drive every resonator is a core topic in switching architectures, especially the detection of the resonance to perform a feedback loop. We demonstrated in this work a transparent and non-invasive way to detect light in a ring waveguide, based on the doped junction already used to drive the ring. Finally, we tackle the question of the switch scalability (without use of active amplifiers). Starting from reasonable hypothesis, we estimate the total switch bandwidth of a classical architecture taking into account data rate, number of ports and the wavelength multiplexing. Those system results confirm or invalidate some of the hypothesis taken in the architecture part

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Benayon, Eduardo Rodrigues. "Roteamento e alocação de comprimento de onda em redes WDM segundo algoritmo baseado em regras da natureza". Universidade do Estado do Rio de Janeiro, 2012. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7433.

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O surgimento de novos serviços de telecomunicações tem provocado um enorme aumento no tráfego de dados nas redes de transmissão. Para atender a essa demanda crescente, novas tecnologias foram desenvolvidas e implementadas ao longo dos anos, sendo que um dos principais avanços está na área de transmissão óptica, devido à grande capacidade de transporte de informação da fibra óptica. A tecnologia que melhor explora a capacidade desse meio de transmissão atualmente é a multiplexação por divisão de comprimento de onda ou Wavelength Division Multiplexing (WDM) que permite a transmissão de diversos sinais utilizando apenas uma fibra óptica. Redes ópticas WDM se tornaram muito complexas, com enorme capacidade de transmissão de informação (terabits por segundo), para atender à explosão de necessidade por largura de banda. Nesse contexto, é de extrema importância que os recursos dessas redes sejam utilizados de forma inteligente e otimizada. Um dos maiores desafios em uma rede óptica é a escolha de uma rota e a seleção de um comprimento de onda disponível na rede para atender uma solicitação de conexão utilizando o menor número de recursos possível. Esse problema é bastante complexo e ficou conhecido como problema de roteamento e alocação de comprimento de onda ou, simplesmente, problema RWA (Routing and Wavelentgh Assignment problem). Muitos estudos foram realizados com o objetivo de encontrar uma solução eficiente para esse problema, mas nem sempre é possível aliar bom desempenho com baixo tempo de execução, requisito fundamental em redes de telecomunicações. A técnica de algoritmo genético (AG) tem sido utilizada para encontrar soluções de problemas de otimização, como é o caso do problema RWA, e tem obtido resultados superiores quando comparada com soluções heurísticas tradicionais encontradas na literatura. Esta dissertação apresenta, resumidamente, os conceitos de redes ópticas e de algoritmos genéticos, e descreve uma formulação do problema RWA adequada à solução por algoritmo genético.
The advent of new telecommunication services resulted in a huge increase of data traffic in the transmission networks. New technologies were developed and implemented over the years to attend to this growing demand, and the optical transmission technology stands. It has advanced greatly, due to the optical fibers large capacity of information transmission. Actually, the best technology to exploits the capacity of the fiber is the wavelength-division multiplexing (WDM), allowing the transmission of multiple signals over a single optical fiber. The WDM optical networks have become very complex, with huge capacity (terabits per second), to attend the ever growing need for bandwidth. In this context, it is extremely important to use the networks resources in an intelligent and optimized way. One of the biggest challenges in an optical network is choosing a route, and selecting a available wavelength on the network to attend a connection request using the least amount of resources. This problem is quite complex, and is known as the routing and wavelength assignment problem or simply RWA problem. Many studies were conducted in order to find an efficient solution to this problem, but it is not always possible to combine good performance with low execution time, a fundamental requirement in telecommunications networks. Genetic Algorithms have been used to solve hard optimization problems, as is the case of the RWA problem, and has produced remarkable results when compared to traditional heuristics found in the literature. This work presents an overview of the concepts of optical networks and genetic algorithms, and describes a formulation of RWA problem that is adequate for solution by genetic algorithm.

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Kopniczky, Judit. "Nanostructures Studied by Atomic Force Microscopy : Ion Tracks and Nanotextured Films". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3763.

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Gafur, Abdul. "Dispersion Effects on OCDMA System Performance". Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5479.

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This thesis presents the effect of dispersion and Multi Access Interference (MAI) of optical fiber on the Bit Error Rate (BER) performance of a Direct Sequence Optical Code Division Multiple Access (DS-OCDMA) network by means of intensity modulation and optical receiver correlators. By using Matlab simulations, Signal-to-Noise Ratio (SNR) versus Received Optical Power (ROP) of an OCDMA transmission system can be evaluated with a so-called 7-chip m-sequence for different numbers of system users. This can be done for the ROP versus BER for various lengths of single mode optical fiber by taking into consideration the dispersion effect in the optical fiber. Matlab simulations can be performed in order to illustrate the reduction of the dispersion index gamma, or to visualize different scenarios, e.g., what amount of transmitted power is required in order to obtain a BER of 10-9 when the length of the optical fiber is increased.

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Habarka, Ondrej. "Úprava nanomanipulátoru používaného v elektronovém mikroskopu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254391.

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Cílem této diplomové práce je zlepšit chování nanomanipulátoru, používaného v elektronovém mikroskopu, při vykonávaní nejmenších kroků pohybu. První částí je analýza mechanismu za účelem nalezení možných řešení problému. Dále se práce zabývá testováním řešení jako je optimalizace tuhosti předepínacích pružin mechanismu anebo změna mazání šnekového převodu mechanismu. Výsledkem práce je výběr nejvhodnějšího řešení problému na základě výsledků testů a následná modifikace nanomanipulátoru.

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Manfrin, Stilante Koch. "Proposta e implementação de um receptor optoeletrônico integrado para redes ópticas passivas (PONs) empregando multiplexação por divisão de comprimento de onda (WDM)". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-01122015-101424/.

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O presente trabalho descreve o desenvolvimento e implementação de duas configurações distintas de um receptor optoeletrônico integrado. A primeira configuração é similar a um projeto encontrado na literatura mas apresenta diversas modificações que lhe conferiram melhor desempenho em comparação ao projeto original. A segunda configuração é uma nova proposta deste trabalho. O receptor foi desenvolvido e implementado visando sua aplicação em redes de comunicações ópticas passivas (PONs) de alta velocidade comutadas a pacote, para possibilitar a utilização da técnica de multiplexação em comprimento de onda (WDM), aumentando assim a capacidade de transmissão da rede, em particular no ramo de ligação da rede de serviços com o usuário final, denominado rede de acesso. O principal objetivo do receptor aqui desenvolvido foi proporcionar uma sintonia rápida entre os canais disponíveis na rede, possibilitando sua seleção num tempo inferior àquele necessário para a transmissão de um único pacote de informação, diminuindo assim o atraso de sintonia e, por conseguinte, a perda de informação. Para tanto, os circuitos integrados implementados e caracterizados referem-se aos circuitos de chaveamento eletrônico e do amplificador de transimpedância das duas configurações investigadas. Os dados experimentais obtidos para as duas configurações confirmaram a previsão de chaveamento dos canais de entrada num intervalo de tempo da ordem de alguns nanosegundos, o que é totalmente compatível com a velocidade de transmissão das aplicações a que se destina este receptor (aproximadamente 5 Gbits/s). Adicionalmente, são apresentados os dados experimentais relativos à freqüência de corte, ganho direto, isolação, relação on/off e características de ruído dos circuitos implementados.
The present work describes the design and implementation of two configurations of an integrated optoelectronic receiver. The first one is similar to a previously reported design but with some modifications to improve its performance. The second one is a new proposal of this work. The goal of the receiver design and implementation was its application in high bit rate packet-switched passive optical networks (PONs) employing the wavelength division multiplexing (WDM) technique to increase the network capacity, in particular on the connection branch of the network core with the final user, the access network. The main goal of the receiver design was to achieve a fast channel tuning, allowing a tuning time smaller than the required for the transmission of a single information packet, decreasing the tuning latency and, therefore, the rate of information packet loss. In order to accomplish this goal, the implemented and tested integrated circuits include the electronic switching circuit and the transimpedance amplifier for both configurations investigated. The measured data for both configurations confirm the expected input channel switching time results, of about a few nanoseconds, which is certainly useful for the expected bit rate of operation (approximate 5 Gbps). Additionally, experimental results concerning cutoff frequency and bandwidth, direct gain, isolation, on/off ratio, and noise characteristics of both implemented circuits are presented.

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Jacobsson, Fredrik. "DPSK modulation format for optical communication using FBG demodulator". Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2307.

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The task of the project was to evaluate a differential phase shift keying demodulation technique by replacing a Mach-Zehnder interferometer receiver with an optical filter (Fiber Bragg Grating). Computer simulations were made with single optical transmission, multi channel systems and transmission with combined angle/intensity modulated optical signals. The simulations showed good results at both 10 and 40 Gbit/s. Laboratory experiments were made at 10 Gbit/s to verify the simulation results. It was found that the demodulation technique worked, but not with satisfactory experimental results. The work was performed at Eindhoven University of Technology, Holland, within the framework of the STOLAS project at the department of Electro-optical communication.

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Eilers, Gerriet. "Molecular Approaches to Photochemical Solar Energy Conversion : Towards Synthetic Catalysts for Water Oxidation and Proton Reduction". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7875.

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Cunha, Inês Maria Sérvulo Correia Ribeiro da. "Revisiting electronic word-of-mouth (e-WOM) : a systematic review". Master's thesis, 2021. http://hdl.handle.net/10400.14/35380.

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Electronic word-of-mouth (e-WOM) is a concept originating from traditional communication of marketing messages from person-to-person word-of-mouth. Research over time, points out to a digital shift in forms of communication. In the modern age consumers are connected 24/7 to the internet, putting products and services under their stringent vigil. Thereby, e-WOM arises with the emergence of online communication amongst consumers relatable to their products and services experience. The topic of e-WOM has been receiving great attention worldwide due to its power in affecting consumer’ purchase behaviour and business performance. Nonetheless as an evolving phenomenon in the market, literature has grown very rapidly and in multiple ways, becoming fragmented. Recognising the importance of e-WOM as a research topic, this systematic review was developed with the purpose of mapping the key themes of e-WOM pertaining to literature for the past ten years. By doing Given this, we used Leximancer qualitative software to extract input from a pool of 64 articles from 2010 to 2020 with the keyword: e-WOM. The results endorse e-WOM relation with other four other themes such as “media”, “influence”, “hotel” and “relationship”. The content analysis of the themes not only contributed to theory by offering directions for future researchers but combining an overall reflection on the state-of-the-art of e-WOM phenomenon.
O electronic word-of-mouth (e-WOM) é um conceito baseado na comunicação e no marketing tradicional de pessoa para pessoa. A investigação de formas de comunicação ao longo do tempo aponta para uma mudança resultante da evolução digital. Na era moderna, os consumidores estão ligados 24 horas por dia à internet, escrutinando em permanência produtos e serviços. Neste contexto, o e-WOM resulta da comunicação online entre consumidores que partilham experiências, produtos ou serviços. O tema do e-WOM tem vindo a receber uma atenção particular graças à sua capacidade de afetar o comportamento de compra dos consumidores e o desempenho das organizações. No entanto, como fenómeno em evolução no mercado, a literatura cresceu muito rapidamente e de forma variada. Reconhecendo a importância do e- WOM como tema de investigação, esta revisão sistemática foi desenvolvida com o objetivo de mapear os principais temas do e-WOM relativos à literatura temática nos últimos dez anos. Neste sentido, foi utilizado o software qualitativo Leximancer com o objetivo de extrair significado de um conjunto de 64 artigos, de 2010 a 2020, com a palavra-chave: e-WOM. Os resultados sustentam a relação do e-WOM com outros quatro temas, tais como, "media", "influência", "hotel" e "relacionamento". A análise de conteúdo dos temas não só contribuiu para a teoria, apontando direções a futuros trabalhos de investigação, mas também uma reflexão geral sobre o estado da arte do fenómeno e-WOM.

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Dickmänken, Inna. "The impact of extreme levels of electronic word-of-mouth volume on suspicion and choice intention". Master's thesis, 2021. http://hdl.handle.net/10400.14/35388.

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Online product reviews have become a relevant information source and sales driver in the online purchase decision process. Being aware of the positive effects, many online sellers engage in measures to increase their amount of highly-rated reviews. Consequently, the instrument of reviews itself and fake reviews in particular became highly relevant for researchers, who put effort into understanding the effects of electronic word of mouth (eWOM) – especially its metrics of valence, the review’s star rating, and volume, the number of reviews – on variables such as purchase intention, perceived and suspicion. The author elaborates on existing research and uncovers that until now no attention has been devoted to the possible effects of extreme values of review volume, although prevailing, e.g., on Amazon. This thesis attempts to fill the identified research gap by proposing consumers use a heuristic approach to interpret the meaning of these metrics. By means of an experiment, the author analyses whether extreme values of review volume in the beginning of the purchase decision process, namely consideration set formation, work as a suspicious cue that implies suspicion and deters consumers from adding a product to their consideration set. The results reveal that an extreme volume does not lead to consumer suspicion, only valence does. Further, it was shown that this resulting feeling of suspicion weakens choice intention while an extreme volume has no impact on choice intention. This thesis is a first contribution to fill the research gap of extreme values of volume.
As opiniões de produtos online tornaram-se uma fonte de informação relevante e um motor de vendas no processo de decisão de compra online. Conscientes dos efeitos positivos, muitos vendedores online tomam medidas para aumentar a quantidade de opiniões altamente positivas. Consequentemente, as opiniões e, em particular, as opiniões falsas tornou-se um tópico altamente relevante para os investigadores, que se têm debruçado sob este assunto na tentativa de compreender os efeitos da word-of-mouth electrónica (eWOM) - especialmente as métricas de valência, a quantidade de estrelas, e o volume, a quantidade de opiniões - sobre variáveis tais como intenção de compra e suspeita. Até ao momento não se tem dado atenção aos possíveis efeitos dos valores extremos do volume de opiniões, embora prevaleçam, por exemplo, na Amazon. Esta tese tenta preencher esta lacuna de investigação, propondo que os consumidores usam uma abordagem heurística para interpretar o significado destas métricas. Através de uma experiência, a autora analisa se os valores extremos do volume de opiniões no início do processo de decisão de compra, nomeadamente a formação de um conjunto de considerações, funcionam como uma pista heurística que origina suspeita e dissuade os consumidores de considerar esse produto. Os resultados revelam que o volume em si não resulta em suspeita, mas a valência sim. Para além disso, mostrou- se que este sentimento de suspeita resultante enfraquece a intenção de escolha, enquanto volume extremo não tem impacto na mesma. Esta tese é uma primeira contribuição para preencher a lacuna da investigação de valores extremos de volume.

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41

Lecoq-Vallon, Antoine, e Mikaël Besse. "The influence and management of the electronic Word-of-Mouth within the French tourism industry". Thesis, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35046.

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Purpose The purpose of the paper is to understand how crucial of importance is e-WOM within the French tourism industry with a focus on trip retailers – travel agencies and tour-operators – by observing and analyzing how they encourage and manage e-WOM. Methodology The paper uses deductive approach with a triangulation method based on a qualitative research through 24 semi-structured telephone interviews and a quantitative research through the behavior analysis of 112 trip retailers on online communities. Findings It was found that the French trip retailers encourage e-WOM by primarily joining and using online communities via posting pictures and special offers at least twice a week on social networks. Besides, among those that collect and manage positive and negative comments, they mainly do it on Facebook by rather adopting a non-defensive attitude. Managerial implications The authors suggest trip retailers not use as many online communities they can but regularly be active on the one(s) they choose to use. Moreover, responding not only to negative but also to positive e-WOM may be a strategy that paid off since few trip retailers take it into consideration. Regarding the management of negative e-WOM, the authors recommend against deleting non-eulogistic comments and reply publicly within 24 hours. Limitations This study was limited to French trip retailers and cannot consequently be generalised for all international trip retailers. Additionally, the specific sector trip retailers work with has not been taken into consideration. Moreover, even if trip retailers have been classified within four categories, no deeply correlation has been studied between the size and their online activity. Further research suggestions Future research is needed to possibly confirm and subsequently generalise the findings of this paper to the overall tourism industry in France. Moreover, it is necessary to compare what trip retailers think to do and what they really do on the web and determine a degree of relevance. Furthermore, due to the constantly growing interest for online communities by tourism professionals, an updated study of that one should be conducted during the next five years and results compared. It would be finally also interesting to measure the impact of e-WOM on online communication strategies Article classification Qualitative and quantitative studies

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42

NGAMNATE, NADA, e 陳明熙. "Factors Affecting Electronic Word-of-Mouth (E-WOM) Usage on the Customer Purchase Intention Investigate on Beauty Market". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/83fkr6.

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碩士
國立虎尾科技大學
企業管理系經營管理碩士班
106
The purpose of this study is to understand which factors influence on using E-Word of mouth (E-WOM) in purchase intention towards beauty products. The data was collected from 299 respondents in Thailand and Taiwan and was analyzed by confirmatory factor analysis in LISREL 8.8. The result of the model testing indicated that expertise and experience of the source do not influence on E-WOM usage. Conversely, trustworthiness, attractiveness, similarity, and familiarity of the source significantly influence on E-WOM usage. Implications for beauty industry firms and suggestions for future study are provided.

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43

Lin, Yue-Yu, e 林悅羽. "The Study of Word of Mouth(WOM) Influencing Factors in B2C Electronic Commerce -Yahoo Online Auction as an Example". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/93017574522400635385.

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碩士
國立彰化師範大學
資訊管理學系所
96
Electronic commerce causes the network auction to become a popular commercial trade pattern recently. There are many kinds of products and transparence information which provide the consumers with the new shopping channels. However, anyone can get into the auction market easily. It attracts many people to join the auction and become the online seller. Today, the auction market is getting more and more mature. Many online sellers start to consider how to manage their own auction position properly. Therefore, they are able to catch the massive customers form the numerous competitors. In the past, research suggests that the word of mouth (WOM) is a reliable information channel which the consumers trusted and used frequently. People are used to consulting their friends for inexperienced consuming behavior before making decision. Therefore, this research discusses that after the consumer shopping from the online auction, which factor can influence them on word of mouth (WOM). Research finds that “quality of service”, “quality of products” and“feedback” are critical factors that can impact consumer on WOM. Futhermore, agreeableness can influence people whether they actually do it or not. I hope the research conclusion will be useful for the online auction sellers to upgrade their service and get more and more consumers. Moreover, I propose some implication for management.

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44

Abreu, Mafalda Sofia Monteiro de. "Influência da perceção do e-wom no brand equity : um estudo sobre marcas de luxo". Master's thesis, 2018. http://hdl.handle.net/10400.26/24434.

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O luxo constitui um setor em constante crescimento, com um valor associado que acompanha essa tendência. A par do seu crescimento, também as novas tecnologias evoluíram de forma exponencial, especialmente as redes sociais e plataformas de e-commerce. Contudo, as marcas de luxo não se ajustaram imediatamente ao contexto online e existe atualmente ainda alguma resistência por parte de certas marcas. Na verdade, o online e as redes sociais potenciam uma maior conectividade e a interação entre utilizadores, através do electronic word of mouth ou e-WOM, que pode exercer influência sobre o valor que cada consumidor tem de determinada marca (brand equity). O presente estudo pretende investigar a influência do e-WOM sobre o brand equity de marcas de luxo, de modo a compreender esta relação e para que se possam construir estratégias para potenciar a presença online destas marcas. Para o efeito, adotou-se uma metodologia mista de investigação, recorrendo a entrevistas semiestruturadas para compreender a definição de marcas de luxo e identificar as caraterísticas diferenciadoras associadas a este tipo de marcas; e o questionário a uma amostra da população portuguesa (n=365) com o intuito de identificar a influência do e-WOM sobre o brand equity de marcas de luxo. Os resultados obtidos mostram que a definição de marca de luxo é subjetiva, pelo que não há consenso na literatura, contudo, compilando fatores essenciais como as caraterísticas diferenciadoras e considerando a subjetividade inerente, é possível alcançar uma definição genérica de marca de luxo. Finalmente, o estudo permitiu ainda concluir que existe uma associação positiva entre o e-WOM e o brand equity de marcas de luxo, elucidando a influência do primeiro sobre o segundo. Estes resultados elucidam a importância do e-WOM que poderá alavancar a presença online da marca de luxo e potenciar o brand equity destas na mente do consumidor.

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45

Liao, Yuan-Tsan, e 廖元燦. "The effect of perceive justice, electronic WOM, repurchase intention on service recovery of online pricing error – Using attribution theory as moderator". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/63341307008612541342.

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碩士
逢甲大學
國際經營管理碩士學位學程
100
nline shopping is a major way of business transaction with the fast development of internet. There were some mistakes that famous company done. For example, Dell’s online store offered a great discount and Apple did too. However, the right of consumer is higher and higher so that seller can’t neglect it and they should compensate consumer carefully to prevent lose them and even more spread negative word of mouth when online pricing error was happened. Before understanding how to do service recovery, seller should understand that does consumer was satisfied or not and the willing to consume again or spread the positive word of mouth. However, there are countless reason that may affect consumer’s perceive and this research would like to know that Attribution theory is the moderator or not. What’s more, this research setting Apple and Acer as the brand, high and low price as the product, money or discount as the compensate ways to examined the difference of perceive fairness and repurchase intension and electric word of mouth and so on. As the structure of this research, there are three parts of the relationship. First is the effects of scenario to perceive fairness. Scenario includes the psychological distance of brand, compensation ways, price of products. Second is taking Attribution theory as moderator and test it is or not. Third is the effects of perceive fairness to repurchase intention an electric word of mouth. The data for this study were collected from questionnaire and using Spss, Amos to finish the analysis. According to the hypothesis analysis, this research finding some answer as following: 1.When Acer happened online pricing error, there were effects with Attribution theory as moderator. 2. When Acer happened online pricing error, consumer-company identification will not be positive to repurchase intention. 3. When Apple happened online pricing error, consumer will be satisfied with discount as a compensation. 4. When Apple happened online pricing error, there were effects with Attribution theory of locus of control and stability. 5. When Apple happened online pricing error, consumer-company identification will not be positive to repurchase intention. Meanwhile, post-recovery satisfaction will not be positive to electric word of mouth.

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46

Jhuang, Ting-Yi, e 莊廷毅. "The Effect of Social Media Fatigue and Satisfaction With Interpersonal Relationship Toward User’s Electronic Word-of-Mouth（e-WOM）Sharing Intention". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/39412371752967866162.

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碩士
國立中央大學
資訊管理學系
104
The escalating acceptance of social networking, coupled with the phenomenal growth in on-line business opportunities, result in waves of companies plunge into social media marketing as a key marketing strategy. However, the popularity of social media usage leads to interference with users’ personal lives, and increases the risk of privacy exposure. In many cases, this negative factor, together with excessive usage, results in user fatigue, burnout and even negative attitude towards social media. Each and every user develops a unique networking behavior and social relationship, based on their personality traits, and their attitudes toward the Internet are also affected accordingly. This study attempts to understand the ways social media fatigue and personality traits affect their behavior in sharing word-of-mouth information on social networks. A research model is proposed based on related literature. Facebook was used as the research settings, and online questionnaires were distributed online. 224 valid samples were collected, and analyzed SPSS, AMOS and SmartPLS 3.0. Analysis reveals that: (1) the user's satisfaction on their social media interpersonal relationships negatively affects social media fatigue, (2) users with higher degree of social media fatigue are less inclined to share word-of-mouth information online, (3) the effects of user's emotional exhaustion in social media fatigue towards sharing intention is moderated by narcissism personality traits, and the higher degree of narcissism has higher degree of moderation.

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47

Wang, Yi-Ju, e 王怡如. "The Study of the Relationship of Electronic Word of Mouth, Consumers' Acceptance of WOM, Tie Strength and Purchase Intention - A Case Study of Internet Mail Order Clothing Brand “Lativ”". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/7242uz.

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碩士
嶺東科技大學
企業管理系碩士班
103
This study will eWOM into positive and negative word of mouth reputation, reputation and word of mouth to explore the Internet network fashion consumer acceptance of the purchase intent of the relationship, whether due to deliver a message to contact consumers of intensity different, and have different effects. In the data collection and analysis, mining questionnaire, the survey will be online as Lativ facebook fan page to browse the Internet Fashion eWOM of online shopping consumers in order to grant staff paid and the Internet in two ways, total 168 questionnaires were recovered, and SPSS18.0 reliability and validity analysis, descriptive statistics analysis, independent sample t test, univariate analysis, linear regression analysis. This study is two-factor experimental design includes two independent variables (eWOM: positive word of mouth / negative word of mouth) × 2 (contact intensity: close contact / weak link), this study found that positive word of mouth and Lativ network of Fashion negative reputation, the reputation of consumer acceptance of no significant differences; and stronger consumer associates strength, reputation higher acceptance; contact strength of close contact or weak links, positive and negative word of mouth no statistical significance; reputation acceptance of purchase intention significantly affect the relationship. Finally, this study proposes the following management advice and management implications, network of fashion, not only the pursuit of promotion eWOM, should enhance the interactive platform for exchange of views, and there is the use of consumer contact locking strength strong platform for the exchange of who is the target market, prompting consumers willingness to buy.

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48

Alboqami, H., W. Al-Karaghouli, Y. Baeshen, I. Erkan, C. Evans e Ahmad Ghoneim. "Electronic word of mouth in social media: the common characteristics of retweeted and favourited marketer-generated content posted on Twitter". 2015. http://hdl.handle.net/10454/14009.

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No
Marketers desire to utilise electronic word of mouth (eWOM) marketing on social media sites. However, not all online content generated by marketers has the same effect on consumers; some of them are effective while others are not. This paper aims to examine different characteristics of marketer-generated content (MGC) that of which one lead users to eWOM. Twitter was chosen as one of the leading social media sites and a content analysis approach was employed to identify the common characteristics of retweeted and favourited tweets. 2,780 tweets from six companies (Booking, Hostelworld, Hotels, Lastminute, Laterooms and Priceline) operating in the tourism sector are analysed. Results indicate that the posts which contain pictures, hyperlinks, product or service information, direct answers to customers and brand centrality are more likely to be retweeted and favourited by users. The findings present the main eWOM drivers for MGC in social media.

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49

Fernandes, Ana Sofia Jaques Afonso. "The impact of negative eWOM on the brand equity of telecommunication companies". Master's thesis, 2018. http://hdl.handle.net/10400.14/25538.

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Social media platforms have been growing in importance for consumers and marketers, by allowing brands to build a closer relationship with their consumers. Nowadays, Facebook is used as tool to reach new consumers and engage with the current ones. Nevertheless, the facilitated interactions may also carry indirect costs since when dissatisfied with the brands’ service, consumers may publicly complain about it in social media. These negative electronic Word-of-Mouth (eWOM) may influence other users who are exposed to negative contents and affect their brands’ perceptions. Despite the relevance of this topic, current studies have not yet sufficiently addressed it. Therefore, this investigation aims at understanding the impact that negative eWOM on brands’ Facebook pages have on the Consumer-Based Brand Equity (CBBE) of those who are exposed to negative contents. While evaluating the effects on the CBBE, the following constructs are considered: Brand Attitude (BA), Perceived Brand Quality (PQ), Re-Patronage Intentions (RPI) and Negative WOM Intentions (NWOM). Additionally, to evaluate if the others’ support on Facebook had an impact on the constructs, the number of “likes” in the negative posts was considered as a moderator. Then, the online survey had a total of 335 respondents and the telecommunication industry was chosen for this study because of its high negative eWOM volume (Liu et al., 2017). The results indicate that the PQ, RPI and NWOM are significantly influenced by the negative valence of the post. However, the number of “likes”, do not moderate the effects. Limitations are discussed and future studies suggested.
As redes sociais têm-se tornado importantes para os consumidores e para os marketers, permitindo que as marcas estabeleçam relacionamentos mais próximos com seus consumidores. Atualmente, o Facebook é usado como uma ferramenta para alcançar novos consumidores e interagir com os atuais. No entanto, este tipo de interação pode, também, ter outros custos indiretos, pois quando os consumidores estão insatisfeitos com o serviço das empresas têm a tendência a reclamar publicamente nas redes sociais. Este electronic Word-of-Mouth (eWOM) negativo pode influenciar outros utilizadores que estão expostos a conteúdos negativos e afectar a percepção da marca. Apesar da relevância do tópico, os estudos atuais ainda não o abordaram adequadamente. Portanto, esta pesquisa tem como objetivo compreender o impacto do eWOM negativo no Facebook tem sobre o Consumer-Based Brand Equity daqueles que estão expostos aos conteúdos negativos. Ao avaliar os efeitos no CBBE, são considerados as seguintes dimensões: Brand Attitude (BA), Qualidade de Percepção da Marca (PQ), Intenções de Re-Patronage (RPI) e Intenções Negativas da WOM (NWOM). Além disso, o número de “gostos” nos comentários negativos foi usado como moderador nas dimensões propostas. Em seguida, o questionário online teve um total de 335 inquiridos e a indústria de telecomunicações foi escolhida para este estudo devido ao volume alto de eWOM negativo (Liu et al., 2017). Por fim, os resultados indicam que a PQ, a RPI e a NWOM são significativamente influenciados pela valência negativa dos comentários. No entanto, o número de "gostos", não modera os efeitos. Limitações são discutidas e futuros estudos sugeridos.

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Chen, Yu-Dong, e 陳鈺棟. "High transparent and low resistivity of WO3/Ag/WO3 multilayerprepared by electron beam evaporation". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/58107408822883249683.

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碩士
明新科技大學
化學工程與材料科技系碩士班
102
The transparent conductive film in the visible region of the photon wavelength (400 ~ 700 nm) having a high transmittance and low resistance characteristics. This thesis, tungsten trioxide / metal oxide / tungsten trioxide in the glass layer are stacked, and the transmittance of a multilayer electrically conductive film were studied. Preparation of silver to copper metal thin films for use in an electron beam evaporation method: tungsten oxide dielectric layer. Studied optical properties and electrical properties of tungsten trioxide. When tungsten oxide / Ag / tungsten oxide multilayer structure having silver thick enough, and its structure has a low resistance, high visible light transmittance, the transparent multilayer film can be used as the conductive thin film electrode. Discussion silver thickness underlying tungsten trioxide, correlation of the optical and electrical properties of the surface of the tungsten trioxide and tungsten oxide / Ag / tungsten oxide stack of layers. The value of the quality factor of experiments used to find an optimal multi-layer structure with excellent electrical conductivity and transmittance of the film. Tungsten oxide / Ag / tungsten trioxide in the quality factor of the visible wavelength of 550 nm was formed in 1.2 × 10-1 (Ω-1). This results indicate that tungsten trioxide (50 nm) / Ag (15 nm) / tungsten trioxide (50 nm) to meet the relevant requirements of transparent conductive films with low resistivity high visible transmittance. In this study, also the insertion of different metals as a comparison. Tungsten oxide / copper / tungsten trioxide in a multilayer film, the visible light transmittance (wavelength of taking 550 nm) was 62.6%, the quality coefficient of 5.6 × 10-4 (Ω-1).

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