This thesis deals with the structure of the optical wireless link intended for indoor applications. Optical transmitters and optical receivers as the basic elements of optical links and their characteristics and parameters are described. The characteristics of lenses used in the transmitter and receiver are presented. The special chapter is devoted to the directional reflectance properties of surfaces. The last part of the thesis is focused on a specific proposal of the wireless optical links and its power level diagram.

At Saab Aerostructures they are manufacturing a lot of parts for Airbus and Boeing. When these components are investigated using finite element analysis four-node Kirchhoff shell elements and a very fine mesh is often used. In order to make the pre-processing easier Saab would like to offset the shell mid surface from the nodal plane (the modeling surface) rather than to extract mid surfaces for the entire component. This would also make it easier to model a component which needs a thickness change later on, this since the original modeling surface could be used but with an offset of the elements in order to represent the new geometry. When offset is used in Nastran multi point constraints are created between the nodes and the shell mid surface points. All loads, which are applied in the nodal plane, are then transformed to the mid surface where the stiffness matrices, displacements and stresses are calculated. In order to be able to use this method more knowledge about its effects are needed, which is the reason for this thesis work. The offset is studied for two simpler cases, thickness variation and a 90°corner, as well as fora more complicated component called a C-bar. This is a hinge connecting the flaps to the wings of an airplane. The simpler cases are modeled using both mid surface and offset models subject to either a transverse load, an in-plane load or a bending moment. These are compared to a solid model in order to determine which is the most accurate. When mid surface modeling is used fort he thickness variation the surfaces are connected using rigid links. The conclusion made from these simulations is that using offset may give different results if the load is an in-plane load. This kind of load leads to the creation of a bending moment, which is linearly dependent on the amount of offset. The severity of this depends on the overall geometry and how this load is applied.

Les références de temps et de fréquence sont largement distribuées sur réseaux informatique et de communications, pour une large gamme d'applications scientifiques et industrielles. Poussé par une demande pour de meilleures performances, un certain nombre de nouvelles méthodes de transfert de temps et de fréquence sur des réseaux à fibres optiques ont été développées ces dernières années. Dans cette thèse, notre objectif est de développer une approche de transfert de temps et de fréquence multi-utilisateurs, compatible avec les réseaux de télécommunications et compétitive avec la distribution de temps par GNSS. Nous nous intéressons donc aux méthodes pour les réseaux à commutation par paquets, comme le NTP (Network Time Protocol) et le PTP (Precision Timing Protocol). Nous nous concentrons également sur les liaisons “unidirectionnelles”, où les signaux aller et retour entre les nœuds de réseau se propagent sur des fibres distinctes, non au sein d’une même fibre (liaisons “bidirectionnelles”). En particulier, nous utilisons une méthode appelée White Rabbit PTP (WR). Développée au CERN, basée sur PTP, utilisant l’Ethernet synchrone et d'autres techniques pour atteindre des performances élevées, WR réalise une stabilité du temps sous-nanoseconde pour la synchronisation d'instruments sur des réseaux à l'échelle de 10 km. Nous sommes particulièrement intéressés par l'extension de cette méthode pour la distribution de références au niveau régional ou national, sur des liaisons allant jusqu'à 1000 km.Nous étudions d’abord les performances de l'équipement réseau White Rabbit, en particulier le commutateur White Rabbit. Nous y apportons diverses améliorations : sur le verrouillage du commutateur grand maître à la référence externe, améliorant ainsi sa stabilité à court terme de plus d'un ordre de grandeur ; sur la bande passante de verrouillage du commutateur esclave ; et en augmentant le débit des messages PTP entre les commutateurs maître et esclave.Nous étudions ensuite les liaisons WR moyennes et longues distances. Nous construisons un lien unidirectionnel de 100 km en utilisant des bobines de fibres dans le laboratoire. Nous découvrons que la performance à court terme est limitée par la dispersion chromatique de la fibre, tandis que la performance à long terme est dégradée par le bruit thermique. Pour limiter l'effet de la dispersion chromatique sur les liaisons longue distance, nous proposons l'utilisation d'une approche en cascade. Nous réalisons un lien en cascade de 500 km, à nouveau avec des bobines de fibres. Nous utilisons le multiplexage en longueur d'onde dense pour construire ce lien par des passages multiples à travers des bobines plus courtes. Nous obtenons une stabilité de transfert de fréquence de 2 × 10-12 à une seconde de temps d'intégration et de 5 × 10-15 en un jour, limitée par le bruit thermique à long terme. Nous obtenons une stabilité temporelle de 5 ps à une seconde de temps d'intégration, diminuant jusqu'à un minimum de 1,2 ps à 20 secondes et restant inférieure à une nanoseconde pour des durées plus longues. Ces performances sont similaires à court terme, et deux ordres de grandeur meilleures à long terme, qu’un récepteur GPS de bonne qualité. Nous nous attendons à ce que les fluctuations thermiques et donc l'effet du bruit thermique des fibres soient réduits d'un facteur d'environ cinq pour les installations sur le terrain.Enfin, nous faisons des études préliminaires sur l'étalonnage en temps des liaisons WR. Le principal défi est de mesurer l'asymétrie de longueur optique entre les deux fibres utilisées pour le transfert des signaux aller et retour. Nous démontrons une technique d'échange de fibres, en utilisant une liaison suburbaine White Rabbit sur fibre noire. Nous décrivons et testons ensuite une nouvelle méthode variationnelle pour l'étalonnage, impliquant une méthode de mesure différentielle basée sur l'exploitation de deux liaisons WR à différentes longueurs d'onde sur la même liaison. / Time and frequency references are widely distributed over communications and computer networks, for a variety of scientific and industrial applications. Driven by a demand for improved performance, a number of new methods for time and frequency transfer over optical fiber-based networks have been developed in recent years. In this thesis our objective is to develop a scalable network time and frequency transfer approach, providing multi-user dissemination, compatible with large telecommunication networks and competitive with GNSS-based time distribution. Therefore we are concerned with methods for use in packet-based networks, like the Network Time Protocol (NTP) and Precision Timing Protocol (PTP). We also concentrate on “unidirectional” links, where the forward and backward signals between network nodes propagate over separate fibers, not within the same fiber (“bidirectional” links).In particular we use a method called White Rabbit PTP (WR). This is a novel technology developed at CERN, based on PTP while using Synchronous Ethernet and other techniques to achieve high performance. It demonstrates sub-nanosecond time stability and synchronization of arrays of instruments over 10 km scale networks. We are particularly interested in extending this method for large scale distribution of references at regional or national level, over links of up to 1000 km.We first study extensively the default performances and limitations of White Rabbit network equipment, in particular the White Rabbit switch. We make various improvements to its operation: on the locking of the grandmaster switch to the external reference, thus improving its short-term stability by more than an order of magnitude; optimizing the locking bandwidth of the slave switch; and increasing the PTP messaging rate between master and slave switches.We then study medium and long-distance WR links. We construct a 100 km, unidirectional link using fiber spools in the laboratory. We discover that the short-term performance is limited by chromatic dispersion in the fiber, while the long-term performance is degraded by the influence of temperature variations on the fiber. To limit the effect of chromatic dispersion for long-haul links, we propose the use of a cascaded approach. We realise a national scale, cascaded, 500 km link, again utilizing fiber spools. We use Dense Wavelength Division Multiplexing methods to construct this link by mutliple passages through shorter spools. We achieve a frequency transfer stability of 2 × 10−12 at one second of integration time and 5 × 10−15 at one day, limited by thermal noise in the long term. We achieve a time stability of 5 ps at one second of integration time, decreasing to a minimum of 1.2 ps at 20 seconds and remaining below one nanosecond for longer averaging times. These performances are similar in the short term, and two orders of magnitude better in the long term, than good quality GPS receivers. We expect thermal fluctuations and therefore the effect of fiber thermal noise to be suppressed by a factor of approximately five for installations in the field.Finally we make preliminary investigations of time calibration of WR links. The main challenge here is to measure the optical length asymmetry between the two fibers used for signal transfer in the forward and backward directions. We demonstrate a fiber swapping technique, using a mid range, suburban White Rabbit link over dark fiber. We then describe and test a new variational method for calibration, involving a differential measurement method based on operating two WR links at different wavelengths over the same optical fiber link.In conclusion, we demonstrate high performance, long haul White Rabbit links for time and frequency dissemination to multiple users. With the level of frequency transfer performance achieved, White Rabbit PTP provides a competitive and scalable technique for comparing industrial atomic clocks at regional and national scales.

A shift has occurred in the traditional type of centralised government control to a more multilevel type of governing referred to as governance. The change from government to governance can be illustrated with an emphasis on networks and social capital enhancement. In higher education this is enveloped through a larger emphasis on institutionalisation of collaboration between the higher education institutions (HEI) and the surrounding environment. In lieu of large block grants come financial incentives through semi-governmental agencies embracing collaboration projects between industry and HEI as well as municipalities.` This licentiate thesis objective is to study the collaboration task’s practical implication on undergraduate education in terms of social capital enhancement and research and teaching links. This is reported in two articles that elaborate on social capital establishment through a policy program and whether policy programs focusing on research collaborations also have an effect on undergraduate education by improving research and teaching links. In general, the findings of this thesis indicate that semi-governmental policy programs have a positive effect on establishing new social capital between regional HEI, industry and municipalities, and that semi-governmentally financed research profiles also have a positive effect on undergraduate education by introducing a link to research outside and within the HEI. / QC 20110117

Jitter requirements have become more stringent with higher speed serial communication links. Reducing jitter, with the main focus on reducing data dependant jitter (DDJ), is presented by employing adaptive finite impulse response (FIR) filter pre-emphasis. The adaptive FIR pre-emphasis is implemented in the IBM 7WL 0.18 µm SiGe BiCMOS process. SiGe heterojunction bipolar transistors (HBTs) provide high bandwidth, low noise devices which could reduce the total system jitter. The trade-offs between utilising metal oxide semiconductor (MOS) current mode logic (CML) and SiGe bipolar CML are also discussed in comparison with a very high fT (IBM 8HP process with fT = 200 GHz) process. A reduction in total system jitter can be achieved by keeping the sub-components of the system jitter constant while optimising the DDJ. High speed CML circuits have been employed to allow data rates in excess of 5 Gb/s to be transmitted whilst still maintaining an internal voltage swing of at least 300 mV. This allows the final FIR filter adaptation scheme to minimise the DDJ within 12.5 % of a unit interval, at a data rate of 5 Gb/s implementing 6 FIR pre-emphasis filter taps, for a worst case copper backplane channel (30" FR-4 channel). The implemented integrated circuit (IC) designed as part of the verification process takes up less than 1 mm2 of silicon real estate. In this dissertation, SPICE simulation results are presented, as well as the novel IC implementation of the proposed FIR filter adaptation technique as part of the hypothesis verification procedure. The implemented transmitter and receiver were tested for functionality, and showed the successful functional behaviour of all the implemented CML gates associated with the first filter tap. However, due to the slow charge and discharge rate of the pulse generation circuit in both the transmitter and receiver, only the main operational state of the transmitter could be experimentally validated. As a result of the adaptation scheme implemented, the contribution in this research lies in that a designer utilising such an IC can optimise the DDJ, reducing the total system jitter, and hence increasing the data fidelity with minimal effort. / Dissertation (MEng)--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted

Existing optical networks are driven by dynamic user and application demands but operate statically at their maximum performance. Thus, optical links do not offer much adaptability and are not very energy-effcient. In this paper a novel approach of implementing performance and power adaptivity from system down to optical device, electrical circuit and transistor level is proposed. Depending on the actual data load, the number of activated link paths and individual device parameters like bandwidth, clock rate, modulation format and gain are adapted to enable lowering the components supply power. This enables exible energy-efficient optical transmission links which pave the way for massive reductions of CO2 emission and operating costs in data center and high performance computing applications. Within the FP7 research project Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) dynamic high-speed energy-efficent transceiver subsystems are developed for short-range optical interconnects taking up new adaptive technologies and methods. The research of eight partners from industry, research and education spanning seven European countries includes the investigation of several adaptive control types and algorithms, the development of a full transceiver system, the design and fabrication of optical components and integrated circuits as well as the development of high-speed, low-loss packaging solutions. This paper describes and discusses the idea of ADDAPT and provides an overview about the latest research results in this field.

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The field of influencer marketing has experienced rapid growth in recent years. However, uncovering the true effectiveness of this marketing approach remains a significant challenge. This thesis addresses the challenge of predicting the effectiveness of influencer marketing campaigns by employing advanced machine learning techniques, specifically the Auto Machine Learning framework Autogluon. With the aim of democratizing machine learning and empowering businesses in the influencer marketing domain, this work leverages Autogluon to predict the interactions generated by influencers when posting affiliate links. By evaluating various settings of AutoGluon and assessing the performance using metrics such as R-squared score, we observed promising results with good predictive accuracy. The findings from our study contribute to critical discussions in the field. This research offers a streamlined and efficient approach to machine learning, reducing the need for extensive manual model tuning and enabling marketers to make informed decisions and optimize their campaign strategies. The outcomes of this study have practical implications for businesses, allowing them to effectively predict campaign interactions and maximize the impact of influencer marketing initiatives. By leveraging the power of automated machine learning, this thesis opens up new opportunities for businesses to harness the potential of influencer marketing in driving successful marketing campaigns. / Influencer marketing trenden har ökat markant de senaste aren men effektiviteten av denna marknadsföringsmetod är till stor del oviss. Denna avhandling utfårskar svårigheten med att förutse effekten av influencer marketing kampanjer med hjälp av avancerad maskininlärningsteknik, specifikt Auto Machine Learning-ramverket Autogluon. Med målet att demokratiserar och uppmuntra företag att använda maskininlärning, utforskar denna avhandling Autogluon för att förutse interageringar som genereras när influerare publicerar affiliate länkar. Genom att utvärdera olika inställningar av Autogluon och analysera olika data som till exempel R-kvadratvärde observerade vi lovande resultat med god förutsägbar precision. Resultaten från vår studie bidrar till kritiska diskussioner inom området. Denna forskning erbjuder en strömlinjeformad och effektiv metod för maskininlärning, vilket minskar behovet av omfattande manuellt modellarbete och möjliggör för marknadsförare att fatta informerade beslut och optimera sina kampanjstrategier. Resultaten av denna studie har praktiska implikationer för företag, vilket gör det möjligt för dem att effektivt förutse interaktioner i kampanjer och maximera effekten av influencer marketingvertyg. Genom att applicera automatiserad maskininlärning öppnar denna avhandling nya möjligheter för företag att dra nytta av potentialen hos influencer marketing för att driva framgångsrika marknadsföringskampanjer.

The mutual need between organizations and startups, from one side to stay competitive and the other to survive, leads to open innovation relationships. However, the actors are asymmetrical, leading to a risk that no value is created. Nevertheless, value needs to be created in the relationship to enable open innovation. This study identifies in literature four relational factors. The aim is to investigate how a startup and established organization perceive the relational factors of actor bonds, resource ties, activity links, network embeddedness, and their influence on value creation. Six semi-structured interviews are conducted. The main findings are: (I) all the relational factors influence value creation in this context. Thus, all are needed to enable an open innovation process (II) each theme that emerged in theory was confirmed (III) each actor􏰈s perceptions were found to be different, demonstrating that value is determined differently depending on the unique actor, their needs and context. Therefore, each actor needs to put more emphasis on the specific themes that actors in the relationship find valuable (IV) new themes are found to influence the relational factor of actor bonds (V) the level of value created depends on how the relational factors are managed by the actors.

Le manque de données et de littérature sur le sujet de la production de marchandises dangereuses dans les parcs industriels présente des incertitudes quant au portrait de ces entreprises dans la province de Québec. La nécessité de développer un portrait global sur la situation des firmes qui produisent des marchandises dangereuses dans la province est donc nécessaire pour comprendre leur répartition, leurs caractéristiques, leurs liens aux différents moyens de transport ainsi que les risques. L’objectif de ce mémoire est donc de présenter un portrait de l’état des entreprises qui produisent et/ou fabriquent des marchandises dangereuses dans les parcs industriels pour comprendre leur répartition, leur relation aux différents moyens de transport ainsi que leur rôle dans l’économie québécoise. Ce projet comporte quatre volets : le premier porte sur l‘analyse cartographique des sites d’entreprises présents dans les parcs industriels, le deuxième développe une typologie des entreprises productrices de marchandises dangereuses dans les parcs industriels, le troisième analyse les liens intermodaux présents dans les parcs industriels où des marchandises dangereuses sont produites et le dernier fait l’étude de trois parcs industriels possédant différents liens intermodaux. Pour ce faire, les données du Registraire des entreprises du Québec (REQ) sont centrales pour déterminer les sites d’entreprises présents dans les parcs industriels ainsi que ceux qui produisent des marchandises dangereuses pour ainsi développer un portrait géographique et une typologie. Aussi, les données des parcs industriels construits à partir des données des schémas d’aménagement et de développement des MRC sont essentielles pour analyser les liens intermodaux ainsi que les études de cas. Ainsi cette étude fournit un portrait global de la production de marchandises dangereuses dans les parcs industriels de la province ainsi que des liens de ceux-ci aux divers moyens de transport, et aux enjeux de risque associés aux firmes qui produisent des marchandises dangereuses. / The lack of data and literature concerning the production of dangerous goods in industrial parks presents uncertainties about the portrait of these companies in the province of Quebec. The need to develop a global landscape of the firms producing dangerous goods in the province is therefore necessary to understand their distribution, their characteristics, their links to various modes of transportation as well as the risks. The objective of this memoir is therefore to present a picture of the companies that produce and/or manufacture dangerous goods in industrial parks in order to understand their distribution, their access to means of transportation and their role in the province’s economy. This project covers four aspects: the first concerns the cartographic analysis of the companies’ sites where dangerous goods are produced in industrial parks, the second develops a typology of companies producing dangerous goods in industrial parks, the third analyzes the intermodal links present in industrial parks where dangerous goods are produced and the last one studies three industrial parks presenting different intermodal links. To carry out this project, data from the “Registraire des entreprises du Québec (REQ)” are central to determining the sites of companies that are present in industrial parks as well as those where dangerous goods are produced in order to develop a geographical portrait and typology. Also, the industrial parks data, that are built from the “Schéma d’aménagement et de développement” of every regional county municipality are essential to analyze intermodal links in the parks as well as the three case studies. Thus, this study provides a global landscape of the production of dangerous goods in the industrial parks of the province and the links of the parks to various means of transportation, as well as the risks issues associated with firms producing dangerous goods.