Half-Duplex Multiuser Multiple-Input Multiple-Output (HD MU-MIMO) systemscurrently employed in communication systems are not experiencing the selfinterference(SI) problem but they are not optimal in terms of efficiency and interms of resources used (time and frequency resources). Ignoring the effect of largescalefading, we start by explaining the uplink (UL) and downlink (DL) parts ofthe MU-MIMO system and how the sum-rate is calculated. We also introduce thethree linear receivers/precoders, Maximum-Ratio Combining (MRC)/Maximum-Ratio Transmission (MRT), Zero-Forcing (ZF), and Minimum Mean-Square Error(MMSE) and which of the three types is going to be used in the study of Full-Duplex Multiuser Multiple-input Multiple-output (FD MU-MIMO) system. Thenwe introduce FD MU-MIMO system, and how the equation used to calculate thesum-rate of the UL part changes when the SI occurs, and why SI problem is notpresent in the DL part. Next, we introduce the spectral efficiency (SE), and howto calculate it and why it is taken as a parameter to compare HD and FD systems.Also the effect of SI on FD MU-MIMO system is presented through simulationgraphs, then we move to show how to reduce SI effect by increasing the number ofantennas in the base-station (BS). Lastly, we take the effect of large scale fading inorder to reach a simple statistical model in the form cumulative distribution function(CDF) graph for different values of SI and compare those of FD MU-MIMOsystem to HD MU-MIMO. The results show that FD MU-MIMO together withmassive MIMO technology is very promising and would save time and frequencyresources which means an increase in the SE but SI must be below a certain level.

Extraction of metals from the seafloor has been considered for decades, beginning with manganese nodules in the 1970s. Today, the targets are massive sulphide deposits rich in copper, zinc, gold, and silver that are associated with hydrothermal vents or black smoker chimneys that occur at divergent and convergent plate margins such as mid-ocean ridges and volcanic island arcs respectively. A recent objective of the mining industry is to develop industry practices that coincide with concepts of sustainability or sustainable development. This objective, known by some as sustainable mining, has indeed become an essential part of the commissioning of any new project, regardless of geographical location. While there has been much work on sustainable mining practice for terrestrial mining, these frameworks are not directly applicable to seafloor projects. There are two problems facing the development of a seabed mining industry. First, there is a regulatory vacuum when considering the mining of seabed deposits, leading to important policy issues. Second, the economic, environmental, and social impacts of a seabed mining project are theoretical, and the real impacts are unknown. Thus, the identification, characterization, and analysis of the sustainability issues facing a seabed mining project are essential steps. To assist with performing these three steps, this thesis provides a process model based on the IDEF0 (Integration DEFinition) standard to assess seafloor massive sulphide mining projects from sustainable mining perspectives. This adaptation of IDEF0 provides a clear, visual representation of a hierarchical framework that can be used to identify “go no-go” sustainability criteria to assist decision makers interested in the potential development of an ore body. / Thesis (Master, Mining Engineering) -- Queen's University, 2011-12-12 12:54:28.436

Hydrothermal discharge on the seafloor results in significant accumulation of base- and precious-metal-rich sulfide material. Technological advances as well as elevated metal prices have led to a growing interest in the direct mining of these deposits from the modern ocean floor. The research presented in this thesis details an investigation of the size, grades, distribution, and accumulation rates of these deposits on the seafloor. A three-part resource assessment, originally designed for land-based ore deposits, was used to generate a predictive framework for the global seafloor sulfide resource. Using detailed descriptions of sizes, grades and locations for 92 known deposits, a resource estimate was generated that predicts a total of ~1,000 deposits and a total global abundance of 600 Mt of sulfide within the neovolcanic zones of the modern ocean floor. A detailed study of the hydrothermal sulfide deposits along the Endeavour Segment of the Juan de Fuca Ridge was carried out to investigate the processes of sulfide accumulation at the ridge-segment scale. Results of 226Ra/Ba dating of barite within the deposits indicate that hydrothermal activity has been ongoing for ~6,000 years and venting has been continuous at the Main Endeavour and High Rise vent fields for ~2,300 and 850 years, respectively. Abundant older sulfide samples from inactive sites outside of the main vent fields indicate a complex history of venting along the ridge segment. Analysis of high-resolution bathymetry of the Endeavour Segment, generated from eight autonomous underwater vehicle surveys, revealed the location of 581 individual hydrothermal sulfide edifices along 15 km of ridge length. Using GIS-based software, the volume of each edifice was calculated, and the total amount of sulfide at Endeavour is estimated to be 1.2 Mt. This estimate is the first comprehensive resource evaluation on the seafloor at this scale. Sulfide has been accumulating within the Endeavour axial valley at a rate of ~400 tonnes per year, which is similar to estimates for the TAG deposit on the Mid-Atlantic Ridge. Using endmember hydrothermal fluid chemistry data and estimates of fluid discharge rates, the mass accumulation rate calculated for Endeavour corresponds to a sulfide depositional efficiency of 6%.

Simulation technique has been used for a feasibility study of a deep exploration project for massive sulphides in an old mining district, the Skellefte field. The outcome under very different conditions has been studied. Under the specific conditions of the well known Skellefte field it is found to be possible to even calibrate the mathematical model.It is found that when the geology is not known in detail, an outcome of the order of 50 tons per meter drillhole is to be expected under a simple drilling strategy.When a certain knowledge about the general structures down to around 1 000 m is established, it is possible to improve the outcome by a factor of 2 through an optimization of the depth of investigation. The optimal depth of investigation is in the order of 500 m.On the other hand, when a minimum ore value is introduced as a function of depth, the expected outcome will again decrease with a factor of about 3.It must be underlined, that these results are average values in a mathematical model and do not say anything about the outcome in the single exploration case. However, in exploration campaigns of the order of 40 drillholes to a depth of 1000 m an analysis shows that at least one deep seated large body was found in 25% ot the exploration campaigns.Faced with the problem whether to go or not to go into a deep exploration phase, this technique can headlight the problem and it can give an estimate about the order of costs and benefits. / digitalisering@umu

General relativity describes gravity in terms of an interacting massless spin-2 field - the graviton. This 100-year-old theory has been spectacularly successful in explaining observations. However, theoretical exploration and the cosmological constant problem motivate the study of alternative theories of gravity. Recently, there has been great progress in understanding theories that give the graviton a mass. This thesis considers several aspects of these massive spin-2 effective field theories and related theories. These theories are first studied from the perspective of scattering amplitudes. The most general 2 → 2 scattering amplitude is constructed for theories containing a single massive graviton or vector. These amplitudes are then used to find the highest strong coupling scales in such theories, assuming a particular scaling of fields and momenta. Generalisations to include additional fields and self-interactions for massive higher-spin fields are also discussed. Constraints that arise from the existence of an ultraviolet completion are then studied. It is shown using dispersion relation arguments that the pseudo-linear massive spin-2 theory cannot admit an analytic, Lorentz-invariant, and unitary ultraviolet completion, but that such completions are not ruled out for massive vector theories. The behaviour of massive spin-2 theories under dimensional reduction is also explored. Stability conditions and the lower-dimensional spectrum are derived for the Kaluza-Klein dimensional reduction of a partially massless graviton and a massive graviton on an Einstein product manifold. Additionally, the nonlinear dimensional reduction of the zero modes in dRGT massive gravity is shown to produce a mass-varying massive gravity theory. Lastly, attempts to construct a version of unimodular gravity containing a massive graviton are discussed. A candidate theory is proposed and is shown to have pathologies. Dimensional reduction is then used to generate massive spin-2 theories with noncanonical kinetic terms and auxiliary fields. These theories are shown to be equivalent to the Fierz-Pauli theory, which provides further evidence for the uniqueness of the kinetic term used in dRGT massive gravity.

No description available.

Hydrothermal discharge on the seafloor results in significant accumulation of base- and precious-metal-rich sulfide material. Technological advances as well as elevated metal prices have led to a growing interest in the direct mining of these deposits from the modern ocean floor. The research presented in this thesis details an investigation of the size, grades, distribution, and accumulation rates of these deposits on the seafloor. A three-part resource assessment, originally designed for land-based ore deposits, was used to generate a predictive framework for the global seafloor sulfide resource. Using detailed descriptions of sizes, grades and locations for 92 known deposits, a resource estimate was generated that predicts a total of ~1,000 deposits and a total global abundance of 600 Mt of sulfide within the neovolcanic zones of the modern ocean floor. A detailed study of the hydrothermal sulfide deposits along the Endeavour Segment of the Juan de Fuca Ridge was carried out to investigate the processes of sulfide accumulation at the ridge-segment scale. Results of 226Ra/Ba dating of barite within the deposits indicate that hydrothermal activity has been ongoing for ~6,000 years and venting has been continuous at the Main Endeavour and High Rise vent fields for ~2,300 and 850 years, respectively. Abundant older sulfide samples from inactive sites outside of the main vent fields indicate a complex history of venting along the ridge segment. Analysis of high-resolution bathymetry of the Endeavour Segment, generated from eight autonomous underwater vehicle surveys, revealed the location of 581 individual hydrothermal sulfide edifices along 15 km of ridge length. Using GIS-based software, the volume of each edifice was calculated, and the total amount of sulfide at Endeavour is estimated to be 1.2 Mt. This estimate is the first comprehensive resource evaluation on the seafloor at this scale. Sulfide has been accumulating within the Endeavour axial valley at a rate of ~400 tonnes per year, which is similar to estimates for the TAG deposit on the Mid-Atlantic Ridge. Using endmember hydrothermal fluid chemistry data and estimates of fluid discharge rates, the mass accumulation rate calculated for Endeavour corresponds to a sulfide depositional efficiency of 6%.

Dans le domaine des télécommunications sans fil, les domaines applicatifs sont de plus en plus larges, s’étendant par exemple du grand public, à la voiture connectée, à l’internet des objets (IoT Internet of Things) et à l’industrie 4.0. Dans ce dernier cas, l’objectif est d’aboutir à une flexibilité et à une versatilité accrues des chaînes de production et à une maintenance prédictive des machines, pour ne citer que quelques exemples. Cependant, les réseaux sans fil actuels ne sont pas encore en mesure de répondre aux nombreuses lacunes de la quatrième génération des réseaux mobiles (4G) et aux exigences de la 5G quant à une connectivité massive, une ultra fiabilité et des temps de latence extrêmement faibles. L’optimisation des ressources spectrales est également un point très important. La 5G était initialement considérée comme une évolution, rendue possible grâce aux améliorations apportées à la LTE (Long Term Evolution), mais elle ne tardera pas à devenir une révolution et une avancée majeure par rapport aux générations précédentes.Dans ce cadre, la technologie des réseaux massifs ou Massive MIMO (Multiple-Input Multiple-Output) s’est imposée comme l’une des technologies de couche physique les plus prometteuses. L'idée principale est d'équiper les stations de base de grands réseaux d’antennes (100 ou plus) pour communiquer simultanément avec de nombreux terminaux ou équipements d’utilisateurs. Grâce à un prétraitement intelligent au niveau des signaux d’émission, les systèmes Massive MIMO promettent d’apporter une grande amélioration des performances, tout en assurant une excellente efficacité spectrale et énergétique. Cependant certains défis doivent encore être relevés avant le déploiement complet des communications basées sur le massive MIMO. Par exemple, l’élaboration de modèles de canaux représentatifs de l’environnement réel, l'impact de la diversité de polarisation, les stratégies de sélection optimale d’antennes et l'acquisition d'informations d'état du canal, sont des sujets importants à explorer. En outre, une bonne compréhension des canaux de propagation en milieu industriel est nécessaire pour optimiser les liens de communication de l'industrie intelligente du futur.Dans cette thèse, nous essayons de répondre à certaines de ces questions en nous concentrant sur trois axes principaux :1) La caractérisation polarimétrique des canaux massive MIMO en environnement industriel. Pour cela, on étudie des scénarios correspondant à des canaux ayant ou non une visibilité directe entre émetteur et récepteur (Line of Sight – LOS) ou Non LOS, et en présence de divers types d’obstacles. Les métriques associées sont soit celles utilisées en propagation telles que le facteur de Rice et la corrélation spatiale, soit orientées système comme la capacité totale du canal incluant des stratégies de précodage linéaire. De plus, les schémas de diversité de polarisation proposés montrent des résultats très prometteurs.2) En massive MIMO, un objectif important est de réduire le nombre de chaînes de fréquences radio et donc la complexité du système, en sélectionnant un ensemble d'antennes distribuées. Cette stratégie de sélection utilisant la corrélation spatiale du récepteur et une métrique de propagation comme facteur de mérite, permet d'obtenir une capacité totale quasi-optimale.3) Une technique efficace de réduction des ressources lors de l’acquisition d’informations du canal de propagation dans les systèmes FDD (frequency-division-duplex) est enfin proposée. Elle repose sur la corrélation spatiale au niveau de l'émetteur et consiste à résoudre un ensemble d'équations auto-régressives simples. Les résultats montrent que cette technique permet d’atteindre des performances qui ne sont pas trop éloignées de celles des systèmes TDD (time-division-duplex) initialement proposés pour le massive MIMO. / Continuous efforts have been made to boost wireless systems performance, however, current wireless networks are not yet able to fulfill the many gaps from 4G and requirements for 5G. Thus, significant technological breakthroughs are still required to strengthen wireless networks. For instance, in order to provide higher data rates and accommodate many types of equipment, more spectrum resources are needed and the currently used spectrum requires to be efficiently utilized. 5G, or the fifth generation of mobile networks, is initially being labeled as an evolution, made available through improvements in LTE, but it will not be long before it becomes a revolution and a major step-up from previous generations. Massive MIMO has emerged as one of the most promising physical-layer technologies for future 5G wireless systems. The main idea is to equip base stations with large arrays (100 antennas or more) to simultaneously communicate with many terminals or user equipments. Using smart pre-processing at the array, massive MIMO promises to deliver superior system improvement with improved spectral efficiency, achieved by spatial multiplexing and better energy efficiency, exploiting array gain and reducing the radiated power. Massive MIMO can fill the gap for many requirements in 5G use-cases notably industrial IOT (internet of things) in terms of data rates, spectral and energy efficiency, reliable communication, optimal beamforming, linear processing schemes and so on. However, the hardware and software complexity arising from the sheer number of radio frequency chains is a bottleneck and some challenges are still to be tackled before the full operational deployment of massive MIMO. For instance, reliable channel models, impact of polarization diversity, optimal antenna selection strategies, mutual coupling and channel state information acquisition amongst other aspects, are all important questions worth exploring. Also, a good understanding of industrial channels is needed to bring the smart industry of the future ever closer.In this thesis, we try to address some of these questions based on radio channel data from a measurement campaign in an industrial scenario using a massive MIMO setup. The thesis' main objectives are threefold: 1) Characterization of massive MIMO channels in Industry 4.0 (industrial IoT) with a focus on spatial correlation, classification and impact of cross-polarization at transmission side. The setup consists in multiple distributed user-equipments in many propagation conditions. This study is based on propagation-based metrics such as Ricean factor, correlation, etc. and system-oriented metrics such as sum-rate capacity with linear precoding and power allocation strategies. Moreover, polarization diversity schemes are proposed and were shown to achieve very promising results with simple allocation strategies. This work provides comprehensive insights on radio channels in Industry 4.0 capable of filling the gap in channel models and efficient strategies to optimize massive MIMO setups. 2) Proposition of antenna selection strategies using the receiver spatial correlation, a propagation metric, as a figure of merit. The goal is to reduce the number of radio frequency chain and thus the system complexity by selecting a set of distributed antennas. The proposed strategy achieves near-optimal sum-rate capacity with less radio frequency chains. This is critical for massive MIMO systems if complexity and cost are to be reduced. 3) Proposition of an efficient strategy for overhead reduction in channel state information acquisition of FDD (frequency-division-duplex) systems. The strategy relies on spatial correlation at the transmitter and consists in solving a set of simple autoregressive equations (Yule-Walker equations). The results show that the proposed strategy achieves a large fraction of the performance of TDD (time-division-duplex) systems initially proposed for massive MIMO.

Massively multiplayer online environments continue to grow in popularity, with cur- rent technical designs based upon a well-proven client-server model. This approach has some inherent limitations, high costs to provision server resources for peak demands and restriction of the maximum number of concurrent participants within a virtual environ- ment. Incorporating peer-to-peer (P2P) techniques provides developers the opportunity to significantly reduce costs, while also breaking through the barrier of the number of concur- rent participants within a single virtual environment. This dissertation presents a hybrid P2P design incorporating a managed server along with a Voronoi-based P2P overlay for the development of massive virtual environments. In this design, the managed server en- sures a secure computing environment and long-term persistent storage, with the virtual environment simulation distributed among the peers, ensuring computational scalability.

The recent developments in Internet-of-Things (IoT) and the next-generation wireless communication systems (5G and beyond) are posing unprecedented demands for massive connectivity, enhanced spectrum efficiency, and strengthened reliability. Moreover, the conventional orthogonal multiple access (OMA) techniques have approached their fundamental limits or the improvements in performance are marginal. To this end, a paradigm-shift from OMA to massive multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) technology is proposed. The proposed techniques are capable of serving multiple spatially-distributed user nodes/IoTs in the same frequency-time resource block by reaping out the benefits of power-domain NOMA, and favorable propagation and channel hardening brought by very large antenna arrays.First, a comprehensively literature survey has been conducted. Next, system, channel and signal models were developed by considering practical transmission impairments of the proposed massive MIMO NOMA. Then, novel NOMA relaying strategies via massive MIMO with pilot designs, per-hop and cascaded channel estimation, statistical-parameter based power allocation policy, and reliable precoding scheme are designed. Then, a complete analytical framework to derive the fundamental performance metrics is developed. A MATLAB-based simulation framework is developed to verify the proposed system designs.Then, the detrimental effects of residual interference caused by intra-cluster pilot sharing and error propagation caused by imperfect successive interference cancellation are quantified. The results acquired can provide insights for refining the proposed techniques in terms of signal model and pilot design.Trade-offs among massive connectivity and spectral efficiency will be established and refined for the proposed relay aided/cell-free massive MIMO NOMA via carefully designing per-hop and cascaded channel estimation, low-complexity statistical-parameter-based power allocation, and conjugate precoding schemes. The proposed technique is expected to significantly outperform the conventional OMA scheme in all overloaded system scenarios by virtue of the proposed aggressive spatial multiplexing and power-domain NOMA techniques. Hence, the proposed technique can simultaneously serve many users with fast data rates than that of the existing OMA techniques. The proposed NOMA techniques are expected to provide higher spectral and energy efficiencies with ultra-low end-to-end latency than those of existing OMA. Thus, the proposed relay-aided/cell-free massive MIMO NOMA can significantly contribute as a novel candidate technology for the next-generation wireless standards.