Γείωση είναι η αγώγιμη σύνδεση ενός σημείου κάποιου κυκλώματος ή ενός μη-ρευματοφόρου μεταλλικού αντικειμένου μιας εγκατάστασης με το έδαφος, με σκοπό να αποκτήσουν το ίδιο δυναμικό με τη γη, το οποίο θεωρείται –κατά σύμβαση- ίσο με μηδέν. Σκοπός ενός συστήματος γείωσης είναι να μεταφέρει και να διαχέει το ρεύμα σφάλματος στη γη, εμφανίζοντας τη μικρότερη δυνατή αντίσταση στη διέλευση του ρεύματος στον ελάχιστο δυνατό χρόνο. Με αυτόν τον τρόπο ελαττώνεται ο κίνδυνος ηλεκτροπληξίας και παρέχεται ασφάλεια κατά την εκδήλωση σφάλματος ή σε περίπτωση κεραυνού, τόσο για τους χρήστες όσο και για τον εξοπλισμό της ηλεκτρολογικής εγκατάστασης. Αποτελεί απαραίτητο τμήμα των ηλεκτρικών εγκαταστάσεων για να εξασφαλιστεί η σωστή λειτουργία τους αλλά και η ποιότητα της παρεχόμενης ηλεκτρικής ισχύος. Τέλος παρέχει ένα δυναμικό αναφοράς για τα ηλεκτρικά σήματα στον τομέα των τηλεπικοινωνιών. Για να επιτευχθούν οι παραπάνω στόχοι πρέπει η αντίσταση γείωσης να έχει πολύ χαμηλή τιμή. Υπάρχουν περιπτώσεις που είναι αδύνατη η τοποθέτηση περισσοτέρων του ενός ηλεκτροδίου διότι η εργασία είναι αρκετά δαπανηρή , είτε λόγω της δομής του εδάφους, είτε λόγω του ανεπαρκή χώρου. Μια εναλλακτική μέθοδος που έχει αναπτυχθεί είναι η χρήση βελτιωτικών υλικών γείωσης γύρω από τα ηλεκτρόδια. Στην παρούσα διπλωματική εργασία τοποθετήθηκαν ηλεκτρόδια γείωσης στο χώρο του Πανεπιστημίου Πατρών και έγινε μέτρηση των αντιστάσεων τους, με σκοπό τη μελέτη της συμπεριφοράς διαφόρων βελτιωτικών υλικών γείωσης σε συνάρτηση με το χρόνο και τις περιβαλλοντικές συνθήκες. Ειδικότερα η διπλωματική αυτή εργασία αποτελείται από τα εξής κεφάλαια: Στο κεφάλαιο 1 πραγματοποιείται μια αναφορά στην ορολογία και στις βασικές αρχές που διέπουν τα συστήματα γείωσης. Ακόμη γίνεται αναφορά στα είδη των ηλεκτροδίων γείωσης και στις διατάξεις που υπάρχουν. Δίνεται επίσης ο ορισμός της αντίστασης γείωσης και παρουσιάζονται οι μέθοδοι μέτρησης της τιμής της.Στο κεφάλαιο 2 περιγράφεται η έννοια και ο ορισμός της ειδικής αντίστασης εδάφους. Στην συνέχεια παρουσιάζονται οι παράγοντες που την ειδική αντίσταση επηρεάζουν και γίνεται αναφορά στους τρόπους μέτρησης της. Τέλος αναφέρονται τρόποι διόρθωσης της αντίστασης γείωσης σε περίπτωση που οι τιμές τις είναι εκτός των επιτρεπτών ορίων. Στο κεφάλαιο 3 γίνεται αναφορά στα βελτιωτικά υλικά γειώσεων και στις βασικές αρχές που τα διέπουν. Επίσης παρουσιάζεται το βελτιωτικό που χρησιμοποιήθηκε στην παρούσα διπλωματική εργασία. Στο κεφάλαιο 4 αναφερόμαστε στα όρια ασφάλειας που πρέπει να πληροί ένα σύστημα γείωσης. Περιγράφεται η αντίσταση του ανθρώπινου σώματος καθώς και οι παράγοντες που επιδρούν στην περίπτωση ηλεκτροπληξίας. Τέλος, με την βοήθεια των ισοδύναμων κυκλωμάτων κατά την διάρκεια του βραχυκυκλώματος δίνονται τα επιτρεπτά όρια τάσης επαφής και βηματικής τάσης. Στο κεφάλαιο 5 περιγράφεται η διεξαγωγή του πειράματος με αναφορά στην εγκατάσταση και στην διαδικασία μέτρησης των ηλεκτροδίων. Στην συνέχεια γίνεται επεξεργασία των μετρήσεων με χρήση διαγραμμάτων. Τελικά καταλήγουμε σε χρήσιμα συμπεράσματα και γίνονται κάποιες προτάσεις για προέκταση της συγκεκριμένης διπλωματικής εργασίας. Τέλος, η διπλωματική εργασία ολοκληρώνεται με το Παράρτημα, στο οποίο δίνονται αναλυτικά οι πίνακες με τα μετεωρολογικά δεδομένα την περίοδο που πάρθηκαν οι μετρήσεις. / Grounding is the conductive connection of a circuit’s point, or of a non-current carrying metallic object of an installation to the ground, in order to obtain the same potential as the earth, which is, by convention, equal to zero. The objective of a grounding system is to transfer and dissipate the fault current to earth, showing the least possible resistance to the passage of current to the minimum possible time. Thereby decreasing the risk of electric shock and provide security in the event of error or in case of lightning, both for users and for the installation of electrical equipment. Finally, provides a reference potential for the electrical signals in the telecommunications sector. To achieve these objectives, the grounding resistance should have very low value. There are cases where it is impossible to insert more than one electrode because the process is quite expensive, either because of the structure of the soil, either because of insufficient space. An alternative method that has been developed is the use of ground enhancing compounds around the ground electrodes. In this diploma thesis grounding electrodes placed in the university of Patras and their resistance was measured, with the aim of studding the behavior of various materials ground improvement in relation to time and environmental conditions. The earthing system is an essential part of power networks, is required for correct operation of the electricity supply network and to ensure good power quality. Specifically this thesis consists of the following chapters: Chapter 1 includes a reference to the terminology and basic principles of grounding systems. Also is referring to the existing types of grounding electrodes and their arrangements. It also gives the definition of ground resistance and presents methods of measuring its value. Chapter 2 describes the concept and definition of soil resistivity. Then follow the factors that affect resistivity and are mentioned ways of measurement. Finally it is mentioned the way of improving the ground resistance if the measured values are unacceptable. Chapter 3 refers to the ground improvement materials and their principles. Also it is presented the ground enhancing compound which was used in this diploma thesis. Chapter 4 is referring to the safety limits of a grounding system. Therefore is described the resistance of the human body and the affecting in case of electric shock. Finally, with the help of equivalent circuits during short circuit the permissible values of touch and step voltages. Chapter 5 describes to the experiment procedure referring to the installation and the process of the measurements. Then follows the processing of the measurements with diagrams. Eventually we arrive at useful conclusions and made some suggestions for extension of this thesis.Finally, in the Appendix there are the meteorological data for the months during which the experiment took place.

Made available in DSpace on 2015-03-26T13:32:16Z (GMT). No. of bitstreams: 1 texto completo .pdf: 1741383 bytes, checksum: 62a62b6f8598963cbe780a77c0cc72a2 (MD5) Previous issue date: 2012-06-28 / Correspondence analysis is a multivariate statistics technique that allows the symultaneous analysis of different categorical variables. It has a simple and intuitive aspect in the presentation of results through perceptual maps. Although correspondence analysis is available in several softwares, including free system R, the main problem that contributes to the lack of knowledge about the potential of this technique and its subsequent diffusion is the existence of several literatures of difficult comprehension, as they present linear algebra with a high level of abstraction and, additionally, for omitting important clarifying steps; on the other hand, the pure and simple reading of interpretation techniques simply become steps lacking in convincing meaning, which may lead to misunderstandings and insecurity in the interpretations and even takes away from the highest possible results. Thus, the aim of this study was to elaborate a clarifying text that showed the mathematical details of all the steps of the correspondence analysis in the form-applied method and with emphasis on its geometric construction. One of the applications of this technique with data from an experiment in the area of genetic improvement of the sugar cane and it allowed important and practical conclusions, such as, the number of talks is a key factor to anticipate the weight of the clump. This information is of the highest importance, since it can facilitate the operational aspects of selection of families for genetic enhancing, and the researcher won t need to wait for harvest season to select the families with the best clump weight traits, as they will be able to select the clump based on largest number of stalks. Therefore, it was concluded that this technique can be promising in the agrarian sciences. Even though the reading of this study takes time and disposal, it contributes to a better understanding of this technique, especially for a layman in algebraic developments, since it provides a complete vision of the step by step of the correspondence analysis through geometric vision and illustrative example. / A análise de correspondência é uma técnica estatística multivariada que permite realizar a análise simultânea de diferentes variáveis categóricas. Possui aspecto simples e intuitivo na apresentação de resultados por meio dos mapas perceptuais. Apesar da análise de correspondência estar disponível em diversos softwares, incluindo o sistema livre R, o principal problema que contribui para o desconhecimento do potencial desta técnica e de sua consequente difusão é a existência de diversos textos especializados de difícil compreensão, por apresentarem um alto nível de algebrismo, abstração e por omitirem passos elucidativos importantes. Por outro lado, a leitura pura e simples das técnicas de interpretação se torna desprovida de sentido convincente, que pode levar a equívocos e insegurança nas interpretações e impede até mesmo de tirar o maior proveito possível dos resultados. Assim, o objetivo deste trabalho foi elaborar um texto elucidativo que mostrasse os detalhes matemáticos de todas as etapas da análise de correspondência, de forma aplicada e com ênfase na construção geométrica. Uma aplicação desta técnica com dados de um experimento na área de melhoramento genético da cana-de-açúcar é apresentada na qual constatou-se que o número de colmos é um fator determinante para antecipar a categoria de peso da touceira. Esta informação é de fundamental importância, uma vez que pode facilitar os aspectos operacionais na seleção de famílias para o melhoramento genético, visto que o pesquisador não necessitará esperar a época da colheita para selecioná-las, pois poderá fazê-la previamente se baseando naquelas com os maiores números de colmos. Portanto concluiu-se que esta técnica pode ser promissora em ciências agrárias. Apesar da leitura do presente trabalho exigir tempo e disposição, o mesmo contribui para um melhor entendimento desta técnica, principalmente para um leitor não muito afeito aos desenvolvimentos algébricos, pois ele fornece uma visão completa do passo a passo da análise de correspondência simples através da visão geométrica e do exemplo ilustrativo.

This thesis investigates which type of user-related/-generated, personal, information is appropriate to share on an interactive public display in a public environment, e.g., user’s names and images, as a mean to enhance interactions with public display applications. This investigation is two-fold, how the content on the public display could be personalized and how interactions with the application can be emphasized. As a specific case of a public display application, an interactive shared music system with a collaborative playlist is chosen. A survey with static prototypes was created and sent out to identify which information users find appropriate sharing, regarding privacy and xyz, but also what information they feel interesting sharing. 47 participants answered the survey and the results informed an iterative design process that generated a series of static and four interactive prototypes. Four groups with three participants in each (third group with only two) were used to discuss the interactive prototypes highlighting the implemented features. In a focus group style setting, the participants were asked various questions for each of the four prototypes addressing this and that. During the sessions, notes were taken, and it was also audio recorded. All the data from all groups were analyzed and then also compared between the four groups. The result showed that people are ok with sharing their username and first name. The content on the music system can be personalized with pop-up notifications which show information about user’s choices, what song do they vote for or what song do they add to the playlist. Furthermore, the new features indicated a positive effect.

Purpose – The purpose of this study is to investigate which product attributes lead consumers to prefer startups’ products over established companies’ products in the specialty product category. The research object is the electric vehicle market in Germany and the product attributes that are researched are alignable attributes, non-alignable attributes and the price. Design/Methodology/Approach – Quantitative data was collected via an internet questionnaire by means of the non-probability sampling techniques convenience and snowball sampling. The data of 408 members of the German Generation Y (age 17 – 38) was used to test six hypotheses by applying ANOVA and multiple linear regression analysis. Findings – It was found that established companies possess a pioneer advantage in comparison to startups for the specialty product ‘electric vehicle’. This advantage can be overcome when startups differentiate their electric vehicles by implementing superior alignable attributes, a valuable non-alignable attribute or a lower price. Superior alignable attributes had the strongest positive influence on consumers’ preferences towards the startup’s electric vehicle, followed by the lower price and a valuable non-alignable attribute. Limitations/Implications – This study is limited to investigating consumers’ preferences without focusing on the reasons behind the preferences. Further, the category of specialty products is represented by only one example, namely the electric vehicle industry. Practical Implications – Startups can benefit from the results by adopting differentiation strategies that were found to be successful in overcoming pioneer advantage. Originality/Value – This study contributes to pioneer advantage literature by researching how startups can successfully overcome pioneer advantage in the specialty product category.

In this research end user privacy preferences regarding online resources web and mobile applications and websites are investigated and design requirements needed for the development of a privacy focused, privacy enhancing technology tool are identified, as derived from the literature, the crowd source based solution is the most appealing solution so it is fully analyzed according to our research main focus.

When an accident is happening most of the time it is the person on the street that is reporting this to SOS Alarm, the instance that is controlling, for example, the ambulances. To ensure that as few mistakes as possible are made it us crucial that the communication between the caller and the ambulance via the SOS Alarm is as efficient as possible. Communication between the caller to SOS Alarm and the ambulance is done by passing through the operator at the SOS Alarm station and then on to the ambulance. Is this the way that it should be handled or are there optional ways that could be used? The technology has evolved since the system used today was installed and today cellular phones are very common and it is not unusual that it is possible to take pictures with these phones. Is this something that could be used to enhance the way information is sent between the caller and the ambulance? These are questions that this thesis tries to answer by using studies at SOS Alarm and Ambulance centrals as a foundation for the arguments. / Fredrik Andrén fredrik@viktig.se 0709-280052

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This study investigates whether family ownership impacts firms’ dividend payout policies by examining firms publicly listed on the Stockholm Stock Exchange (OMX Stockholm) during the years 2013–2018 (1,363 firm-year observations). The investigation is made by performing multiple regression analyses including the dependent variable DIVIDEND PAYOUT. The findings reveal that family firms distribute higher dividend payouts than non-family firms, suggesting that dividends are used as a corporate governance mechanism to mitigate agency problems. Family firms without a second blockholder present have the highest dividends. A family second blockholder appears to collude with the controlling family resulting in lower dividends. A separation between ownership and control results in higher dividends as it implies a worse corporate governance structure. In sum, the results imply that family ownership positively impacts firms’ dividend payout policies in Sweden.

This master thesis has the purpose to analyse and identify smart efficient future solutions within the Maintenance, Repair and Overhaul (MRO) process for aircraft. The efficiency solutions, in form of new technologies and tools, should present a foundation that MRO suppliers can continue to develop to enhance and streamline their maintenance processes. The project was performed as a case study at the aerospace and defense company Saab AB in Linköping, where the company's MRO process was investigated. Through identifying possibilities and alternative technologies available today and in the near future, one continues to have a competitive and future-proof position in the market.  Through an own constructed course of action influenced from established methods, the thesis' purpose and aim was attained. The method was based on authentic approaches for case studies but also inspired by the so-called "Requirement Engineering". The combination of the methods resulted in a precise focus on the relevant subjects, together with a clear structure of the requirements on the technologies to reach a successful implementation. Through a detailed data collection comprised of study visits, interviews, literature studies, market analyses, and document reviews, multiple relevant technologies and requirement-lists for utilization were identified.  To concretize the use and potential improvements with the technologies, the project had the objective to develop a demonstrator with one of the technologies presented. The demonstrator should focus on minimizing the use of paper, which is a common problem among many market actors today. The most promising technology was considered to be a tablet application with an accommodated application. The selection of the tablet solution was based on the motivation that it is a well-established technology and a favorable first step from paperwork.  To conclude this master thesis, a tablet application was developed in Novacura Flow Studio, where the majority of the identified requirements were fulfilled. Beyond the demonstrator, an introduction and analysis of technologies, such as AR-glasses, voice guidance, additive manufacturing, and a digital twin, was presented.

With the recent take back of the country by the Taliban, Afghan women’s experiences of[in]security have again become top-of mind for many. Yet, this renewed focus perpetuates anexisting imagery of Afghan women as powerless victims, with a few rebellious heroines. Thisimage, instrumentalizing women’s experiences, fuels different political agendas that are oftennot helpful to the women. To provide a more authentic image of the women’s sensemakingand experiences of [in]security, I therefore interviewed five Afghan women using a life-storymethodology where the women were included in all stages of the research process. Duringthis project, I took a feminist and critical approach to security: the woman herself defined theconcept, its impact on her life, and how she managed it. Contrary to other similar researchprojects, I asked the women about times they felt safe instead of unsafe to lessen any retraumatization, and to emphasize their opportunity for agency. Listening to the women’sstories, I interpreted the every-day as a site where they enhanced their agency in the face ofloss of control brought on by pervasive insecurities, something they described as a continuousprocess to create safe spaces. During this process, I identified an analytical pattern of how thewomen understood, and thus went about creating these safe spaces, that of adjustment andresistance. Albeit with movement between the two. This pattern shows how complex thewomen’s understanding and reaction to insecurities were as well as their responses, which iskey to understand for any future support for the women of Afghanistan.