This masters'sthesis deals with graph theory and utilization of this theory for design and optimization of data network structures. Introduction chapter describes graph theory in general view, i.e. fundamental terms used for graph description, graph distinguishing, etc. Next part describes graph algorithms, for example a shortest path finding. After this I write about actual routing protocols where the graph algorithms are used. Last but one part deals with queuing theory and final part describes practical presentation of using graph theory for design and optimization of data network structure in Matlab programme environment.

P4 is a high-level language for programming the data plane of a network switch. These P4-programmable switches come with no pre-defined behavior or protocols, so it is entirely up to the loaded P4 program to define these. This allows the user to exclude any unwanted functionality and to create custom protocols. It also removes the dependence on the switch vendor in terms of both trust and addition of new features. This thesis looks at migration from traditional switches to P4-programmable ones. Since no behavior is included out-of-the-box in the P4 switches, a search is made for open-source P4 projects and the functionality they provide is evaluated. It is found that most link layer functionality can be achieved with them, with the exception being loop prevention by spanning tree protocols. Therefore, one of the projects is extended with an implementation of the Rapid Spanning Tree Protocol based on the IEEE 802.1D-2004 standard. Finally, partial migration of networks to P4 switches and to the Software Defined Networking (SDN) paradigm is studied based on a literature review. Four general approaches and specific architectures for these are found, and it is concluded that such a hybrid network can still benefit from P4 and having a centralized SDN controller.

Les réseaux de capteurs sont des réseaux particuliers composés d'objets contraints en ressources. Ils possèdent une faible puissance de calcul, une faible puissance de transmission, une faible bande passante, une mémoire de stockage limitée ainsi qu'une batterie à durée de vie limitée. Afin d'intégrer de tels réseaux dans l'internet des objects, de nouveaux protocoles ont été standardisés. Parmi ces protocoles, le protocole RPL (pour Routing Protocol for Low Power and Lossy Networks). Ce protocole est destiné a construire une topologie logique de routage appelée DODAG. Dans cette thèse, nous abordons l'aspect acheminement de données qui considère une topologie de routage arborescente. L'acheminement des données se fait donc de saut en saut d'un enfant à son parent (ou d'un parent à son enfant). Optimiser la construction du DODAG revient donc à construire un arbre couvrant selon une contrainte donnée. Un arbre couvrant est une structure communicante qui permet de maintenir un unique chemin entre toutes paires de noeuds tout en minimisant le nombre de liens de communication utilisés. De plus, nous considérons les contraintes des réseaux de capteurs telles qu'une batterie déchargée et la variabilité du lien radio comme des fautes transitoires. Ceci nous conduit par conséquent à construire une structure couvrante tolérante aux fautes transitoires. L'auto-stabilisation est une branche de l'algorithmique distribuée qui assure qu'à la suite d'une ou de plusieurs fautes transitoires, le système va retrouver de lui-même un comportement correcte au bout d'un temps fini. L'objectif de cette thèse est de proposer des algorithmes auto-stabilisants dédiés aux réseaux de capteurs. / Spanning Trees from theory to practiceSelf-Stabilizing algorithms and sensor networksAbstract : Sensor networks are composed of ressources constrained equipments. They have low computing power, low transmission power, low bandwidth, limited storage memory and limited battery life.In order to integrate such networks in the Internet of things, new protocols were standardized such as RPL protocol (for Routing Protocol for Low Power and Lossy Networks). This protocol is intended to build a logical routing topology called DODAG (for Destination Oriented Directed Acyclic Graph). In this thesis, we discuss the data routing aspect by considering a tree routing topology. Thus, the routing of data is hop by hop from a child to its parent (or from a parent to its child). Optimize the construction of the DODAG is therefore to build a spanning tree in a given constraint. A spanning tree is a connecting structure that maintains a unique path between all pairs of nodes while minimizing the number of used communication links. Furthermore, we consider the constraints of sensor networks, such as a dead battery and the variability of the radio link as transient faults. This leads us to build a covering structure tolerant to transient faults. The self-stabilization is a branch of distributed algorithms that ensures that following one or more transient faults, the system will find itself a correct behavior after a finite time.The objective of this thesis is to propose self-stabilizing algorithms dedicated to sensor networks. The contributions of this thesis are:In the first part of the thesis, we proposed a self-stabilizing algorithm for the construction of a minimum diameter spanning tree.This construction is natural when we want to minimize the communication delay between a root and all other network nodes. Our algorithm has several advantages. First, our algorithm is limited to memory occupation of O(log n) bits per node, reducing the previous result of an n factor while maintaining a polynomial convergence time. Then, our algorithm is the first algorithm for minimum diameter spanning tree that works as an unfair distribution demon. In other words, we make no restriction on the asynchronous network behavior. In the second part of the thesis, we are interested in the unstable topology built by RPL protocol (DODAG). Our solution is to place an additional constraint on the number of children a node can accept during the construction of the DODAG. This constraint has the effect of reducing the rate of parent change and consequently to improve the protocol performance in terms of packet delivery rate, delay of communication and power consumption. In addition, we implemented a mechanism to update the information of the downward routes in RPL. Furthermore, our solution has the advantage of not generating overhead because we use existing control messages provided by RPL to implement it. Finally, this contribution is twofold since we validated our solution both by simulations and experiments.

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Forskning om Boundary Spanning belyser vikten av gränsöverskridande individer i samverkan, inom och mellan organisationer, på alla ledningsnivåer. Inom det svenska Totalförsvaret sker det exempelvis genom civil-militär samverkan. Emellertid sker samverkan först vid uppkomna situationer och händelser, vilket är alldeles för sent. Det saknas förmåga att förnimma påverkande faktorer som gemensamt måste hanteras. Syftet med studien är att, med stöd av teorierna gällande Boundary spanning och gemensam lägesuppfattning, analysera förmågan inom det svenska Totalförsvaret, i skapandet av gemensam lägesuppfattning. För att kunna identifiera förmågeskapande faktorer valdes att fokusera på händelser som aktiverat det svenska Totalförsvaret. För studien valdes två fall, där det ena fallet innefattades av civil-militär samverkan som skedde innan återtagandet av Totalförsvarsplaneringen (Regeringen 2015a), det andra fallet ägde rum efter återtagandet. Sammanfattningsvis har denna studie visat att det svenska Totalförsvaret som metaorganisation måste öka ingående aktörers förståelse för totalförsvarskonceptet. Även mer insikt i vikten av planerade och spontana länkar, med fokus på mer förberedelser i fredstid. Studien visar också att det inte nyttjades gemensamma system för att skapa en gemensam lägesuppfattning. Det förekom olika syn på ansvarsförhållanden, gemensamma målsättningar och interna friktioner. Teorikombinationen har givit bra möjlighet att förstå förutsättningar, hinder och möjligheter att uppnå gemensam lägesuppfattning i det svenska Totalförsvaret. Den jämförande ansatsen gav bra möjlighet att värdera det svenska Totalförsvarets förmåga att uppnå gemensam lägesuppfattning, där resultatet visar på att förmågan till del måste stärkas.

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I have investigated the properties of the large scale structure of the nearby Universe using data from the Galaxy and Mass Assembly survey (GAMA). I generated complementary halo mass estimates for all groups in the GAMA Galaxy Group Catalogue (G³C) using a modified caustic mass estimation algorithm. On average, the caustic mass estimates agree with dynamical mass estimates within a factor of 2 in 90% of groups. A volume limited sample of these groups and galaxies are used to generate the large scale structure catalogue. An adapted minimal spanning tree algorithm is used to identify and classify structures, detecting 643 filaments that measure up to 200 Mpc/h, each containing 8 groups on average. A secondary population of smaller coherent structures, dubbed `tendrils,' that link filaments together or penetrate into voids are also detected. On average, tendrils measure around 10 Mpc/h and contain 6 galaxies. The so-called line correlation function is used to prove that tendrils are real structures rather than accidental alignments. A population of isolated void galaxies are also identified. The properties of filaments and tendrils in observed and mock GAMA galaxy catalogues agree well. I go on to show that voids from other surveys that overlap with GAMA regions contain a large number of galaxies, primarily belonging to tendrils. This implies that void sizes are strongly dependent on the number density and sensitivity limits of the galaxies observed by a survey. Finally, I examine the properties of galaxies in different environments, finding that galaxies in filaments tend to be early-type, bright, spheroidal, and red whilst those in voids are typically the opposite: blue, late-type, and more faint. I show that group mass does not correlate with the brightness and morphologies of galaxies and that the primary driver of galaxy evolution is stellar mass.

Condensation of Ph2PCH2OH with a range of polyaromatic substituted secondary amines afforded a new set of 'hybrid' phosphine ligands of the type {RCH2N(CH2PPh2)CH2}2 and RCH2N(CH2PPh2)CH2CH3 (R = various planar aromatic groups). The coordination chemistry of these new mono and bidentate ligands towards a range of transition metal centres including Mo(0), Au(I), Rh(I), Ni(II), Pd(II), Pt(II) and Ru(II) was investigated. Ditertiary phosphines of the form {RCH2N(CH2PPh2)CH2}2 were found to be capable of bridging two transition metal centres in addition to forming rare examples of nine-membered cis- and trans- chelate complexes. Single crystal X-ray analysis of these coordination compounds revealed several types of inter- and intramolecular packing interactions (including a C-H···Pt interaction and slipped intermolecular π····π stacking), and also confirmed the rare trans-diphosphine coordination mode. Fluorescent emission measurements have been undertaken on these new tertiary phosphines and their coordination compounds, and these luminescent properties are discussed. A preliminary investigation into the chemosensory behaviour of selected compounds has been undertaken. Using RPCH2OH (RP = Ph2P, Cy2P or AdP = 1,3,5,7,-tetramethyl-2,4,8-trioxa-6- phosphaadamantane) as a versatile precursor, a range of ferrocenyl (Fc) tertiary phosphines have been prepared from a selection of primary and secondary amines. The coordination chemistry of these new mono and bidentate ligands towards several transition metal centres including Cr(0), Mo(0), Au(I), Rh(I), Ru(II), Pd(II) and Pt(II) was investigated. In particular, the previous chemistry was expanded to prepare several new diferrocenyl phosphines of the form {FcCH2N(CH2PR)CH2}2. In a similar manner to their polyaromatic counterparts, these ditertiary phosphines were found to be capable of coordination through both bridging and cis- / trans-chelating modes. Notably, single crystal X-ray analysis was used to confirm the formation of an extremely rare example of a dimeric trans, trans-[Rh(CO)Cl{phosphine}2]2 complex; thought to be the first crystallographically characterised metallacycle containing an Rh2Fe4 arrangement of metal centres. In addition to this {FcCH2N(CH2PR)CH2}2 chemistry, a rare example of a triferrocenyl ditertiary ii phosphine, {FcCH2N(CH2PPh2)CH2}2Fc, was prepared, as well as a macrocyclic ditertiary ferrocenyl phosphine, C10H8Fe(CH2N(CH2PPh2)CH2)2CH2. The coordination chemistry of {FcCH2N(CH2PPh2)CH2}2Fc led to the formation of two unusual examples of pentametallic diphosphine coordination complexes with a Fe3Au2 and Fe3Ru2 arrangement of metal centres. The development of a new phosphinoamine, (Ph2P)2NCH2Fc, and a new ferrocenyl iminophosphine, Ph2PCH(Ph)CH2C(H)NCH2Fc, are also discussed, in addition to a brief investigation of their coordination chemistry. Electrochemical measurements have also been undertaken on these ferrocenyl ligands and their respective coordination compounds (when purity, yield and stability would allow), and their redox chemistry discussed. A series of novel phosphorus(III) containing ligands of the forms (R)N(CH2PPh2)2 and (R)NHCOCH2N(CH2PPh2)2 (R = functionalised planar aromatic or ferrocenyl group) have been prepared. The phosphines were found to readily coordinate several transition metals including Pt(II), Pd(II) and Ru(II) to form a series of new cis- chelate and bridged bimetallic complexes. Analysis by single crystal X-ray diffraction revealed several types of inter- and intramolecular hydrogen bonding within the molecular structures of the phosphines and their coordination compounds, including the formation of several intermolecular 1D chains and the presence of an intramolecular N-H···N bond, which forces a 'scorpion-like' conformation.

This thesis studies the relationship between the first generation biofuels and selected commodities and assets in the USA, Europe, and Brazil. It is the first attempt to combine the taxonomy and wavelet analyses in a single research application. Our unique dataset comprises 32 weekly price series covering the 2003--2015 time period. First, we employ a method of minimum spanning trees and hierarchical trees to model a biofuel-related price network. We demonstrate a development phase shift between Brazilian and the US/EU biofuel industries. We reveal a strong and stable connection between Brazilian ethanol and its main production factor, local sugarcane. We further find that US ethanol is closely linked to corn. In the contrary, European biodiesel exhibits only moderate ties to its production factors. Subsequent wavelet analysis scrutinizes the identified price connections both in time and frequency domains. Both Brazilian and US ethanols are found to be positively related to their respective feedstock commodities. In particular, feedstock proves to lead the price of the biofuel and not vice versa. Moreover, the dynamics remains qualitatively unchanged when controlled for the influence of crude oil.