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<p> This thesis is a contribution to the theory of Steiner quadruple systems. S-cyclic Steiner quadruple systems are defined and then as a main result it is shown that there exists exactly one S-cyclic Steiner quadruple system of order 20.</p> / Thesis / Master of Science (MSc)

Notre étude a pour objet de déterminer l’impact engendré par les infrastructures technologiques sur l’innovation et la croissance économique dans les pays de l’Organisation de Coopération et de Développement Economiques (OCDE). Nous allons nous inspirer de la théorie « Quadruple Helix of Innovation » (QH) pour construire un modèle théorique de croissance économique afin d’évaluer le rôle joué par un ensemble d’infrastructures technologiques, en présence des systèmes ouverts d’innovation et du « Mode 3 » de production des connaissances. Nous avons choisi la récente théorie QH au sein des Systèmes Nationaux d’Innovation (SNI) car elle décrit une nouvelle réalité économique où l’innovation est considérée comme le résultat de la co-création entre les entreprises, les citoyens, les universités et le gouvernement, dans un contexte caractérisé par l'existence de partenariats, de réseaux de collaboration et de relations symbiotiques. Un modèle théorique de croissance économique axé sur la R&D et avec des dépenses publiques productives sera élaboré afin de démontrer l’importance de l’existence des infrastructures technologiques et il sera possible d’apprécier les effets des dépenses publiques productives à travers une étude de « dynamique transitoire » et une analyse empirique fondée sur la nouvelle base de données CANA (2011). / Our study has the aim of defining the impact generated by the technological infrastructure on innovation and economic growth in the countries of the Organization for Economic Cooperation and Development (OECD). We will draw inspiration from the "Quadruple Helix of Innovation" theory (QH) in order to construct a theoretical model of economic growth that will assess the role played by a set of technological infrastructures belonging to different "innovation ecosystems", in the presence of innovation open systems and the "mode 3" of knowledge production. We chose the recent QH theory on National Innovation Systems (NIS) as it describes a new economic reality where innovation is seen as the result of co-creation between businesses, citizens, universities and government, in a context characterized by the existence of partnerships, networks of collaboration and symbiotic relationships. A theoretical model of economic growth based on R & D and on productive public spending will be developed to demonstrate the importance of the existence of technological infrastructure in promoting innovation, and ultimately its contribution to economic growth. This will make it possible to evaluate the effects of productive public spending through a study of "transitional dynamics" and an empirical analysis based on the new database CANA (2011).

<p> This thesis is a contribution to the theory of Steiner quadruple systems. The first chapter provides a construction of resolvable Steiner quadruple systems that is different from the known constructions. In the second chapter, we construct Steiner quadruple systems with an automorphism that consists of a cycle of length 2 plus a cycle of full length minus 2, and investigate the number of pairwise distinct systems of this kind. In the third chapter, we also construct non-S-cyclic Steiner quadruple systems, one of which is an answer to a question raised in [11], and also investigate the number of pairwise distinct systems.</p> / Thesis / Master of Science (MSc)

No description available.

No description available.

The transition toward a robust, resource-effective, and renewable energy system faces many challenges. The demand for electricity is expected to rapidly increase over the coming years due to the electrification of society resulting in a need for more transmission capacity in the grid. Distributed energy systems are argued to be part of this transition and the implementation of small-scale distributed energy resources has grown enormously over the last few years. Energy communities, a way to collectively produce and consume energy in a local context, have been shown to support the energy transition while providing flexibility to the grid. The interplay of actors in energy communities is argued to aid in handling the increased complexity of the energy system. Knowledge sharing is considered fundamental for energy communities to emerge and a way to facilitate the management of knowledge transfer is argued to be important, but not currently existing. The purpose of the study is to explore how knowledge sharing in and between energy communities can be strategically managed and organized, both in terms of aiding the development of energy communities and upscaling the concept. This was achieved by implementing a qualitative approach consisting of a comprehensive literature review accompanied by empirical findings through interviews with relevant actors. The collected data were analyzed by applying the theoretical concepts Quadruple Helix Innovation Systems, Knowledge Management, and Inter-Organizational Systems. The results showed that several key elements must be considered to be successful in sharing knowledge within and between energy communities. The Key Elements Strategy Model is presented as an overall approach that can be adapted for enabling application in different contexts and constellations. Since the concept of energy communities is expected to be further developed, it motivates the implementation of a systematic approach that can be used iteratively to continuously gain, capture and share new knowledge. There is a lot of potential to further investigate the area of knowledge sharing in the development of energy communities and future research on the subject is recommended. / Övergången till ett robust, resurseffektivt och förnybart energisystem står inför många utmaningar. Efterfrågan på el förväntas öka snabbt under de kommande åren då elektrifieringen av samhället leder till ett behov av mer överföringskapacitet i nätet. Distribuerade energisystem hävdas vara betydande i energiomställningen och införande av småskaliga distribuerade energiresurser har vuxit enormt under de senaste åren. Energigemenskaper, ett sätt att kollektivt producera och konsumera energi lokalt, har visat sig stödja omställningen samtidigt som det ger flexibilitet till nätet. Samspelet som krävs mellan de aktörer som ingår i energigemenskaper förväntas kunna bistå i hanterandet av den ökade komplexiteten i energisystemet. En grundläggande aspekt för uppskalningen av energigemenskaper är delning av kunskap. Att hantera kunskapsdelning inom projekten på ett organiserat sätt har pekats ut som väldigt viktigt, men inte existerande i dagsläget. Syftet med studien är att undersöka hur kunskapsdelning inom och mellan energigemenskaper ur ett strategiskt perspektiv bör hanteras och organiseras, både med avseende på att stödja utvecklingen av energigemenskaper samt uppskalning av konceptet. Detta uppnåddes genom att utföra en kvalitativ studie bestående av en omfattande litteraturstudie och intervjuer med relevanta aktörer. Den insamlade datan analyserades genom att tillämpa Quadruple Helix Innovation Systems, Knowledge Management och Inter-Organizational Systems. Resultaten visade att flera nyckelelement måste tas i beaktning för att lyckas med att dela kunskap inom och mellan energigemenskaper. The Key Elements Strategy Model presenteras som ett övergripande tillvägagångssätt som kan anpassas för att möjliggöra tillämpning i olika sammanhang och konstellationer. Eftersom energigemenskaper som koncept förväntas utvecklas vidare så är implementering av ett systematiskt iterativt tillvägagångssätt för att kontinuerligt skapa, fånga och dela kunskap motiverat. Det finns mycket potential att ytterligare undersöka området för kunskapsdelning i utvecklingen av energigemenskaper och framtida forskning i ämnet rekommenderas.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This dissertation presents modal-based techniques for the effective systematic design of quadruple-ridged flared horns (QRFHs) as reflector feeds for radio astronomy applications. A new excitation technique is proposed, consisting of a quadraxial line that terminates in the quad-ridges through the back lid of the QRFH, which allows for the integration with differential low-noise amplifiers. An equivalent circuit of this quadraxial feed is presented that allows fast synthesis of optimal feeding designs for QRFHs. In addition, the quadraxial feeding network suppresses higher-order modes significantly. The effect of eliminating these unwanted modes are investigated and the quadraxial feed is shown to outperform the coaxial feed in the known detrimental aspects of the QRFH – beamwidth narrowing for increased frequency, beamwidth variation over the upper bandwidth, high cross-polarisation levels, high co-polar sidelobes and variable phase centre – for the specific QRFH designs. Ridge-loaded modes are analysed and a large number of cut-off frequencies presented which are unavailable in literature. The pure-mode excitation of the quadraxial feed allows more effective control over the modal content in the QRFH. This is exploited in a proposed design technique where the cut-off frequencies throughout the horn are used to synthesise the ridge taper profile, in order to achieve the desired modal distribution in the aperture. The proposed feeding solution is compact and therefore is also attractive for use with cryocoolers, typically employed with front-end electronics in telescopes for radio astronomy. A prototype was successfully manufactured and the mechanical implementation of the quadraxial feed proved to be much more simple than that of the conventional feed – consisting of a coaxial line realised within the thin ridges. / AFRIKAANSE OPSOMMING: Hierdie proefskrif stel modus gebasseerde tegnieke voor vir die effektiewe sistematiese ontwerp van viervoud gerifte oopgesperde horings (VGOHs) as weerkaatser voere vir radio astronomie toepassings. ’n Nuwe voertegniek word voorgestel, wat bestaan uit ’n kwadraksiale lyn wat termineer in die vier riwwe deur die agterkant van die VGOH, wat die integrasie met differensiële laeruis versterkers toelaat. ’n Ekwivalente stroombaan van hierdie kwadraksiale voer word aangebied vir die vinnige sintese van optimale voer ontwerpe vir VGOHs. Boonop onderdruk die kwadraksiale voer netwerk ook beduidend hoër orde modusse. Die effek van die uitskakeling van hierdie ongewensde modusse word ondersoek en die kwadraksiale voer oortref die gedrag van die koaksiale voer in die bekende nadelige aspekte van die VGOH – bundelwydte vernouing met toenemende frekwensie, bundelwydte variasie oor die boonste bandwydte, hoë kruispolarisasie vlakke, hoë kopolarisasie sybande en wisselvallige fase senter – vir die spesifieke VGOH ontwerpe. Rifgelaaide modusse word geanaliseer en ‘n groot aantal afsnyfrekwensies word aangebied wat nie beskikbaar is in literatuur nie. Die suiwermodus opwekking van die kwadraksiale voer bied meer effektiewe beheer oor die modusinhoud in die VGOH. Hierdie aspek word benut in ‘n voorgestelde tegniek waar die afsnyfrekwensies deur die horing gebruik word om die rif tapsheid profiel te sintetiseer, sodat die gewensde modale distribusie in die stralingsvlak behaal word. Die voorgestelde voer oplossing is kompak en daarom ook aantreklik vir die gebruik met krioverkoelers, wat tipies gebruik word met die voorkant elektronika in teleskope vir radio astronomie. ‘n Prototipe was suksesvol vervaardig en die meganiese implimentasie van die kwadraksiale voer toon dat dit eenvoudiger is as met die gebruiklike koaksiale voer – wat bestaan uit ‘n koaksiale lyn bewerkstellig binne die dun riwwe.

The objective of this study is threefold. The first objective is to provide an integrated perspective towards the territorial engagement of universities and their related models and strategies. The second objective is to verify whether tendencies pointing to an integrated strategy of university engagement are emerging in real settings, while the third objective is to deepen the understanding of the university’s potential contribution to social innovation practices. The first part of the work is devoted to review the literature on the institutionalization of university third mission and its relation to university territorial engagement and it presents an analysis of the different university models and strategies adopted by the academic system to reach engagement goals in the last decades. In this context, the System-based University is introduced as a university model which encompasses an integrated approach to university territorial engagement. Such model is built upon contributions on Civic and Developmental universities and their role in local socio-economic dynamics. It presents itself as an integrated model that includes but goes beyond the focus on technology transfer featuring third mission activities embodied at the beginning of the 21st century by the so-called Entrepreneurial university. The System-based model is represented by three main factors: i) synergy between the core missions of teaching and research and the third mission, ii) alignment between the needs expressed by the territory and the knowledge produced by the university, and iii) a balanced approach to research excellence. The second part of the work proposes an empirical analysis aimed at identifying tendencies towards system-based models of university, in particular within the Italian academic system. This part makes use of multivariate statistical techniques. Eventually, the third part aims at deepening the role of universities in the social innovation realm, drawing on the few contributions on this topic and on a recent stream of research that connects social innovation to quadruple helix model of interaction between government, industry, universities and civil society. Namely, this last part investigates how and why universities may engage in quadruple helix partnerships, applying an exploratory case study methodology on data stemming from the Urban Innovative Actions, a novel European programme in the context of social innovation in urban areas.

Dielectric resonators offer high-Q (low loss) characteristics which make them ideal for filters with narrow bandwidth and low insertion loss specifications. They are mainly used in satellite and wireless system applications. Such applications desire the highest performance filters with the lowest amount of size and mass, which has been the main motivation for size reduction techniques invented over the past three decades for these filters. In addition with the emergence of different communication system technologies, several bands are now required to be supported by a single front-end, calling for emergence and development of dual-band and multi-band filters. To date few work has been done in the area of dual-band dielectric resonator filters. Dielectric resonators filters are important components in many communication systems, when a group of such filters are brought together to perform multiplexing of RF channels. These multiplexer systems tend to be fairly complex and bulky in design, and there is strong desire to reduce their size and mass to the maximum extent possible. Novel quadruple-mode, dual-mode, and dual-band filters as well multiplexers are presented in this thesis. The first ever quadruple-mode dielectric resonator filter using the simple cylinder structure is reported in this work. A cylindrical dielectric resonator sized appropriately in terms of its diameter and height is shown to operate as a quadruple-mode resonator, which is achieved by having two mode pairs of the structure resonate at the same frequency. Single-cavity, quad-mode filters and higher order 4n-pole filters are realizable using this quad-mode cylindrical resonator, offering significant size reduction for dielectric resonator filter applications. The structure of the quad-mode cylinder is then simplified by cutting lengthwise along the central axis of the cylinder, to produce a half-cut cylinder suitable for operation in a dual-mode regime. Novel dual-mode, 2n-pole filters are realizable using this half-cut cylinder, by making the two resonances equal in frequency. The dual-mode half-cut filter is shown to be a strong contender for replacing existing dual-mode filters used in satellite and wireless applications, as it offers superior size and mass characteristics. By making the resonances unequal in frequency, novel dual-band filters and multiplexers are further realizable, by carrying separate frequency bands on different resonant modes of the structure. The first true orthogonal mode dual-band dielectric resonator is presented in this work, using the half-cut structure. Multiplexers are also derived from these dual-band resonators, which greatly reduce size and mass of many-channel multiplexers at the system level, as each two channels are overloaded in one physical branch. Full control of center frequencies of resonances, input and inter-resonator couplings are achievable, allowing realization of microwave filters with different bandwidth, frequency, and return loss specifications, as well as advanced filtering functions with prescribed transmission zeros. Spurious performance of the half-cut cylinder can also be improved by cutting one or more through-way slots between opposite surfaces of the resonator. Size and mass reduction achieved by using the full and half-cut resonators described in this thesis, provide various levels of size reduction in microwave systems, both device and system level.