Made available in DSpace on 2014-10-09T12:28:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:04Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

Made available in DSpace on 2014-10-09T12:33:43Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:39Z (GMT). No. of bitstreams: 0 / Neste trabalho foi desenvolvido um novo método voltado para a caracterização de lentes térmicas em materiais fotônicos, utilizados como meios ativos no desenvolvimento de lasers. Este método baseia-se em interferometria por padrão de speckle eletrônico (ESPI), utilizando dois lasers de diodo multímodo sintonizados a diferentes freqüências. Com o ajuste desta diferença, foi possível escolher uma resolução apropriada para medirmos as variações geradas no raio de curvatura da frente de onda, relacionados ao efeito térmico. Para os nossos experimentos escolhemos uma amostra vítrea de aluminato de cálcio dopado com 4% de érbio; e potências de bombeio incidentes de até 1,76 mW do laser de bombeio. Os lasers de diodo foram sintonizados para ter um intervalo de contorno por volta de 120 m. Com o aumento da potência absorvida pela amostra, observamos a diminuição da curvatura da frente de onda incidente na CCD, devido ao aumento da potência da lente térmica gerada. Através de uma análise paraxial dos feixes, foi feita uma aproximação para obtermos os valores das lentes para cada configuração, apresentando comprimentos focais de 131,39 mm a 42,76 mm. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Type I noise storms constitute a sizeable fraction of the active-Sun component of solar radiation at meter wavelengths. The storms occur over a prolonged duration as intense, narrow-band spikes, superposed on a low-intensity broadband continuum, in the 30-400 MHz frequency range. Either component of the noise storm radiation has a very high degree of ordinary-mode circular polarization (~ 100 %), and is widely believed to be generated by the plasma emission mechanism. Existence of large sunspot groups or active region complexes, with a high degree of complexity and strength in the associated magnetic topology, have a remarkable spatio-temporal correlation to the occurance of noise storms. Hence type I noise storm events were employed as tracers in estimating the solar cycle activity, with specific relevance to resolving the mimimum-phase occuring between solar cycles 22 and 23, to a precise yet unique epoch of 1998 October,in consonance with the monthly average sunspot count and the 10.7 cm solar radio flux data. The latter have a proven close link with associated sunspot activity. Spatio-temporal correlation of energetic eruptive event termed Coronal Mass Ejection ( CME ), with the type I noise storm events has been convincingly established, from the point of view of ``Space Weather'' prediction. A particular aspect of this study has been the choice of limb-event CMEs as against the halo ones; this criterion has aided in an unambiguous position-angle determination for the eruption- site of the CMEs. Noise storms are found to be the precursors, temporally succeeded by the CME events over a time-scale of 1 to 14 hours. Large scale reconfiguration of the photospheric magnetic field topology, by way of reconnection, merging, cancellation or submergence, in the ambience of pre-existing lines of magnetic flux, triggered by the shearing and twisting motion of the footpoints, and leading to the sigmoid-to-arcade evolution of coronal magnetic loops, traces the event-specific linkage involving the type I noise storms and CMEs. Phenomena that occur at metric wavelengths in the solar corona, and vary on short time scales, are investigated, with the aid of a prototype, custom-built antenna-receiver system to the Gauribidanur RadioHeliograph ( GRH ). The GRH is a transit-mode instrument, while the time-delay control implemented on the prototype enables a radio source to be followed, as it traverses the sky at the sidereal rate. The delay-tracking scheme has been implemented on the front-end electronics, as this would eliminate the otherwise cumbersome task of mechanical-steering of the log-periodic dipole array, while also permitting radio observations over a significantly wider frequency band. The performance of the Gauribidanur Prototype Tracking System ( GPTS ) has been validated on the basis of exhaustive tests, in order to characterise its attenuation, phase, and pointing-accuracy, and optimised for solar observations at 77.5 MHz. Continuous Sun observation was performed with the GPTS, over a period from 24th of June, 2002 to 20th of August, 2002. The daily schedule involved solar observations at seven beam-positions on either side of the local meridian,spaced apart by ~ 9 deg., for about four hours each day. Absolute radio flux calibration was performed by following an identical observing schedule for the intense, unresolvable radio source Cygnus A. Periods of enhanced radio emission, corresponding to global rise in the solar radio radiation, were detected on several days. On each of those days of enhanced activity, the absolute deviation from the mean-flux, corresponding to the various beam-positions for that day, was determined. From this, the intra-day quasi-periodicity in solar radio flux was found to be 110 minutes, with the fluctuation in flux being 3 (+/- 1.5) sfu. Positional information from the Nancay (sic) Radioheliograph data, and features of the causative Active Regions of the underlying photospheric disk from the full-disk H-alpha images of the Big Bear Solar Observatory, along with the radio-spectral data published in the Solar Geophysical Data Reports led to conclusion that, heightened flux emission had been the result of the type I noise storms, known for their sharply defined directivity characteristics. The continuum component of type I noise storms is studied for variation in the frequency-dependent flux characteristics. Swept-frequency data from the Gauribidanur Radio Spectrograph, on 26th and 27th September 2000, in the 30-80 MHz band, were analyzed. The quiet-sun and burst components in the acquired data were excised-out. Absolute flux calibration was performed from spectral observations of Cygnus A in the same band. The spectral-index of the continuum was found to be ~ +3.7 . From a knowledge of the continuum source-size at various other spot frequency imaging observations, the source-size of the particular event was estimated, from interpolation and curve-fitting, to be 13.2 +/- 1.2 arcmin. From a knowledge of the continuum radio flux and its source-size, the brightness-temperature was found to vary from 1.07 x 1e7 to 1.96 x 1e7 K, in the 50 - 80 MHz band. Plasma emission is widely believed to bethe radiation mechanism for the continuum. The excitation of plasma waves by trapped, energetic electron beams moving along the coronal magnetic loops, and their coalescence with the low-frequency ion-acoustic waves or upper-hybrid waves excited due to shock-waves generated by magnetic reconnections above the active region complexes, at sites of coronal density inhomogeneities, are the cause for the noise storm radiation. From knowing the brightness-temperature in the source-region, the supra-thermal density in the electron-beam is estimated. Corroborative evidence, in the form of complementary observations for source-size, extent of the active region complexes, and the associated variations in strength and polarity of magnetic flux on the photosphere, the density enhancement over that of the tenuous coronal density, as per the Newkirk's model, above such active regions, the emission-measure, density, and brightness-temperature in the large-scale coronal loops interconnecting the trans-equatorial active regions in this case, in extreme uv and soft X Ray wavelengths, is applied to validate the assumptions, and estimations on various parameters involved in this plasma emission phenomenon. The burst component of type I noise storms is studied with the newly commissioned high temporal and spectral resolution spectrograph at the Gauribidanur Radio Observatory. The bursts reveal themselves as narrow-band, spiked events on the dynamic spectral records, and their occurance is of a stochastic nature. Isolated Type I bursts were chosen based on their bandwidth (2-2.5 MHz ), fractional-bandwidth ( 1.5 ), lifetime ( 1.5 seconds ), and their radio flux (~ 20-40 sfu ) distribution. The dynamic~- spectrum was calibrated from galactic background observations towards the direction of the North and the South Galactic poles. The flux calibration scheme is ideally suited for those radio telescopes capable of a low spatial resolution, wherein the predominant contribution to the system temperature arrives from the galactic background radiation. The frequency and time profiles of the bursts were analyzed on a case-by-case basis. The results of the study reveal that, a majority of the frequency profiles show a remarkable gaussian symmetrical distribution as compared to the less significant assymmetry in either the ascending or the descending limb ( which appear as enhanced tail-like features ) of the corresponding gaussians. This, in consonance with their narrow emission bandwidth, endorses the view that, the source region for Type I bursts are in a state of extreme homogeneity, as regards their plasma density and temperature. The time profiles on the other hand show a greater level of asymmetry on either their ascending or descending segments; deviations from the gaussian fit, to each of the bursts' time profiles, reveal a higher incidence in abrupt rise or fall on either of the limbs, to cases where the profiles conform to a symmetric gaussian. Since the rise and decay in the time profiles correspond to growth of plasma instabilities and damping of the plasma waves, respectively, they portray a region of the turbulent corona that is replete with magnetic reconnections contributing to the energetics of plasma waves.

Light, as a medium for communication, has the unique ability to transmit volumes of data with minimal energy loss. This capability not only sparked the revolution of internet-based communication over fiber optic networks, but also holds the potential to expand computing beyond our current capabilities. At present, data is stored densely in computer chips, but is sent out of the chip through centimeter-long electrical wires in a slow and energy-intensive process, before finally interfacing with optical transmitters. To bypass this bottleneck, electrical channels can be condensed and converted into light over a compact area using integrated photonic chips. In particular, the silicon photonics technology platform offers the potential for extremely dense data communications due to its high confinement waveguides and compact micro-resonators. However, three major obstacles stand in the way of realizing a low-energy and bandwidth-dense implementation of this technology: the integration of photonics with electronics, optical coupling from the photonic chip to fiber, and scaling up link architectures to multiplex data streams onto many wavelengths. The work in this thesis aims to confront these three challenges and advance integrated photonics technology to unprecedented bandwidth densities and energy efficiencies, with a focus on the first challenge of photonic-electronic integration. It begins with an overview of the escalating demand for inter-chip bandwidths and the potential solution offered by integrated photonics. Next, this thesis builds a theoretical framework for the performance parameters and sources of energy consumption that are addressed in the subsequent sections. After this introductory context, the thesis describes the achievement of the highest density and largest scale photonic-electronic integration to date, using a dense, 25 um pitch 3D bonding process. An 80-channel array fabricated in this integration records the lowest data link energies to date, at 120 fJ/bit, and transfers data at 10 Gbit/s/channel for a record 5.3 Tbit/s/mm2 bandwidth density. The discussion then shifts to the issue of chip-to-fiber coupling efficiency, traditionally the greatest source of loss in photonic links. A substrate-removed edge coupler design reduces this loss to a mere 1.1 dB, and an inverse-designed edge coupler taper shows a fourfold length reduction compared to linear tapers. Lastly, the thesis presents designs for wavelength scaling that increase the number of energy efficient channels on a single fiber. Specifically, it demonstrates a multi-channel, polarization diverse micro-comb receiver and a 3D-integrated transceiver with wavelength interleaving to waveguide buses of cascaded resonators. This thesis builds on photonic device developments to introduce photonic systems with the lowest energy and densest data communications to date. Together, these results unlock the tremendous potential of light as a fast and energy-efficient communication medium between chips, paving a sustainable path towards scaling artificial intelligence and disaggregating computation and memory resources.

No description available.

Accurate knowledge of the centimeter- and millimeter-wavelength absorptivity of ammonia is necessary for the interpretation of the emission spectra of the jovian planets. The objective of this research has been to advance the understanding of the centimeter- and millimeter-wavelength opacity spectra of ammonia under jovian conditions using a combination of laboratory measurements and theoretical formulations. As part of this research, over 1000 laboratory measurements of the 2-4 mm-wavelength properties of ammonia under simulated upper and middle tropospheric conditions of the jovian planets, and approximately 1200 laboratory measurements of the 5-20 cm-wavelength properties of ammonia under simulated deep tropospheric conditions of the jovian planets have been performed. Using these and pre-existing measurements, a consistent mathematical formalism has been developed to reconcile the centimeter- and millimeter-wavelength opacity spectra of ammonia. This formalism can be used to estimate the opacity of ammonia in a hydrogen/helium atmosphere in the centimeter-wavelength range at pressures up to 100 bar and temperatures in the 200 to 500 K range and in the millimeter-wavelength range at pressures up to 3 bar and temperatures in the 200 to 300 K range. In addition, a preliminary investigation of the influence of water vapor on the centimeter-wavelength ammonia absorptivity spectra has been conducted. This work addresses the areas of high-sensitivity centimeter- and millimeter-wavelength laboratory measurements, and planetary science, and contributes to the body of knowledge that provides clues into the origin of our solar system. The laboratory measurements and the model developed as part of this doctoral research work can be used for interpreting the emission spectra of jovian atmospheres obtained from ground-based and spacecraft-based observations. The results of the high-pressure ammonia opacity measurements will also be used to support the interpretation of the microwave radiometer (MWR) measurements on board the NASA Juno spacecraft at Jupiter.

Η αλματώδης ανάπτυξη που παρατηρείται τα τελευταία χρόνια στον τομέα των οπτικών δικτύων τηλεπικοινωνιών, έχει ως συνέπεια την αύξηση της κατανάλωσης ενέργειας. Σήμερα υπολογίζεται ότι η ενέργεια που οφείλεται σε IT τεχνολογίες αποτελεί το 1%-2% της παγκόσμιας κατανάλωσης. Ωστόσο, τα ποσοστά αυτά αναμένεται να αυξηθούν δραματικά μιας και όλο και περισσότερες εφαρμογές, που απαιτούν μεγάλο εύρος ζώνης (π.χ. video streaming, HDTV), αναπτύσσονται ταχύτατα. Μέχρι πρόσφατα ο κύριος περιορισμός στην ανάπτυξη των δικτύων ήταν το κόστος εξοπλισμού και μετάδοσης. Σήμερα το μεγαλύτερο πρόβλημα είναι η όλο και αυξανόμενη κατανάλωση ενέργειας. Έτσι λοιπόν πιο energy-aware προσεγγίσεις για το σχεδιασμό, την υλοποίηση και τη λειτουργία των οπτικών δικτύων κρίνονται πλέον απαραίτητες. Για την αντιμετώπιση του προβλήματος της κατανάλωσης ενέργειας σε οπτικά δίκτυα υπάρχουν δυο προσεγγίσεις: η ανάπτυξη ενεργο-αποδοτικών συσκευών δικτύου ή η ανάπτυξη αλγορίθμων δρομολόγησης και ανάθεσης μήκους κύματος (RWA) που να λαμβάνουν υπόψη τους και την ενέργεια που καταναλώνει το δίκτυο. Στην παρούσα διπλωματική εργασία επιλέχθηκε η δεύτερη προσέγγιση όπου και αναπτύχθηκαν Energy Aware RWA αλγόριθμοι για τον σχεδιασμό WDM οπτικών δικτύων με στόχο την ελαχιστοποίηση της ενέργειας που καταναλώνεται. Αυτό επιτυγχάνεται μειώνοντας τον αριθμό των συσκευών του δικτύου, όπως αναγεννητές, ενισχυτές, add/drop τερματικά κ.τ.λ. που είναι γνωστό ότι καταναλώνουν αρκετή ενέργεια κατά τη λειτουργία τους. Αρχικά αναπτύχθηκε ένας αλγόριθμος σε Ακέραιο Γραμμικό Ακέραιο Προγραμματισμό (Integer Linear Programming - ILP) που ελαχιστοποιεί από κοινού όλες εκείνες τις συσκευές του δικτύου που καταναλώνουν ενέργεια. Έπειτα το πρόβλημα χωρίζεται σε δυο υπο-προβλήματα: την κατανομή αναγεννητών σε κόμβους του δικτύου όπου η αναγέννηση είναι απαραίτητη και στο Energy Aware RWA. Σε αυτή τη περίπτωση εκτός από ILP προγραμματισμό εφαρμόζεται επίσης και χαλάρωση των περιορισμών ακεραιότητας (LP προγραμματισμός) ώστε να μπορούν να προκύψουν λύσεις και για μεγαλύτερες τοπολογίες. Για τον υπολογισμό της απόδοσης των προτεινόμενων αλγορίθμων διεξάγονται μια σειρά από πειράματα εξομοιώσεων σε Matlab, με τη βοήθεια του LINDO API για την επίλυση των (I)LP προβλημάτων σε ένα μικρό δίκτυο αλλά και στο ευρωπαϊκό δίκτυο Geant-2. Oι προτεινόμενοι αλγόριθμοι συγκρίνονται με τυπικούς RWA αλγορίθμους που δεν λαμβάνουν υπόψη την ενέργεια ή ελαχιστοποιούν κάποιες από τις συνιστώσες του δικτύου. Οι υπολογισμοί δείχνουν ότι η κατανάλωση της ενέργειας του δικτύου μπορεί να μειωθεί μέχρι και 45% σε δίκτυο με συνδέσμους μονής ίνας και μέχρι και 65% σε συνδέσμους διπλής ίνας. / The continuing deployment and upgrade of optical telecommunication networks drive up power and energy consumption, in a way that makes operators worry that future energy consumption levels may pose constraints on communications growth that are more significant than those posed by bandwidth considerations. As community concerns about global energy consumption grow, the power consumption of the optical networks is becoming an issue of increasing importance. Even though energy consumption of IT-related infrastructure currently represents between 1% and 2% of global energy consumption, such values are destined to rise, as more bandwidth-hungry applications (such as video streaming, and HDTV in particular) continue to be developed. Thus, it seems that an energy-aware approach is increasingly needed during the design, implementation and operation of optical networks. Two different approaches can be explored to reduce energy consumption in optical networks: the improvement of the energy efficiency of the equipment and the energy awareness of the Routing and Wavelengths Assignment (RWA) algorithms. In this work the energy minimization problem in optical networks is considered from an algorithmic perspective. The objective of the proposed algorithms is to plan optical WDM networks so as to minimize the energy consumed, by minimizing the number of the most energy-consuming components. Such components can be amplifiers, regenerators, add/drop terminals, optical fibers, etc. Firstly an Integer Linear Programming (ILP) formulation is given that aims at jointly minimizing the energy consuming modules present in an optical network, such as the regenerators, amplifiers, wavelength selective switches, etc. Then the problem for a general (translucent network) is decomposed into a regeneration placement problem, and an energy-aware RWA for transparent networks problem, where again ILP formulations are given to minimize energy consumption. The ILP of the decomposed problem is solved as an LP problem, by relaxing the integer constraints, in order to obtain solutions for larger network topologies. In order to evaluate the performance of the proposed Energy Aware (EA)-RWA algorithms a number of simulation experiments is carried out. All the RWA algorithms are implemented in Matlab and LINDO API is used to solve the corresponding (I)LP problems. The proposed algorithms are compared with RWA algorithms that do not consider energy minimization techniques or RWA algorithms that partially take into account energy consuming components. The simulation results showed that the energy consumption in the optical layer can be reduced by up to 45% in single fiber networks and by up to 65% in multi-fiber networks.

Made available in DSpace on 2014-10-09T12:38:21Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:07Z (GMT). No. of bitstreams: 1 05678.pdf: 6012797 bytes, checksum: fe9d7fe0fee771d558f91a7bffb7cfa3 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:38:21Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:07Z (GMT). No. of bitstreams: 1 05678.pdf: 6012797 bytes, checksum: fe9d7fe0fee771d558f91a7bffb7cfa3 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Répondre aux questions fondamentales concernant notre compréhension de l’Univers, comme la cause de son expansion accélérée ou la nature de la matière noire, requiert de confronter les théories aux observations. Dans ce contexte, les amas de galaxies peuvent être utilisés comme de puissantes sondes observationnelles. Cependant, à l’heure actuelle, leur utilisation est limitée par des incertitudes et des effets systématiques, qui affectent notamment la mesure de leur masse, que l’on présume dominée par la matière noire. Les amas de galaxies peuvent être étudiés à différentes longueurs d’onde : le gaz chaud qui compose le milieu intra-amas (ICM en anglais) émet des rayons X et est observable dans le domaine millimétrique via l’effet Sunyaev Zel’dovich (SZ), alors que les galaxies rayonnent principalement en optique et infrarouge. Combiner et comparer ces observables permet de réduire les incertitudes et les effets systématiques des contraintes cosmologiques issues des amas. Dans ce contexte, cette thèse a pour but de préparer les grands relevés observationnels du futur comme Euclid et le Large Synoptic Survey Telescope (LSST). Elle présente les analyses multi-longueurs d’onde d’un échantillon d’amas détectés en X dans le relevé XXL, couvrant une large gamme de masses et de redshifts. La première partie de cette thèse introduit le contexte cosmologique et présente les propriétés observationnelles des galaxies et amas de galaxies, ainsi que les ingrédients pour construire des échantillons cosmologiques d’amas. La deuxième partie traite de la caractérisation optique des amas XXL et des propriétés de leurs galaxies membres. Nous commençons par la présentation de XXL et du Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), un relevé optique associé. Ensuite, nous nous concentrons sur la caractérisation de la qualité des redshifts photométriques du CFHTLS et sur leur utilisation pour construire les fonctions de luminosité (LF en anglais) optiques des galaxies d’amas XXL. Il apparaît que la LF des galaxies satellites dépend légèrement de la richesse des amas, le principal proxy de masse en optique, mais ne montre pas d’évolution significative avec le redshift. Ensuite, nous entreprenons l’étude de la couleur et de la fraction de galaxies à noyaux actifs (AGN en anglais) dans les galaxies d’amas XXL et montrons que la masse joue un rôle clé dans la régulation de l’activité de formation stellaire dans les amas. Pour finir, l’algorithme de détection d’amas WaZP est utilisé pour étudier la contrepartie optique des amas XXL. La troisième partie de cette thèse est consacrée au projet observationnel dédié à la cartographie du signal SZ de trois amas XXL distants, avec la camera à haute résolution angulaire NIKA2. La préparation du projet est discutée, en se servant des données optiques et X afin de prédire le signal SZ attendu. Ensuite, nous présentons la procédure d’observation au télescope et la réduction des données, dédiée à la production des cartes SZ étalonnées. Le projet est en cours et un amas, XLSSC102, à z = 0.97, a été observé partiellement. Nous développons ensuite une méthode de détection en aveugle des potentielles galaxies qui peuvent contaminer le signal SZ, permettant la découverte fortuite de galaxies poussiéreuses à haut taux de formation stellaire dans le champ de XLSSC102. La morphologie et l’état dynamique de XLSSC102 sont ensuite caractérisés grâce à la combinaison des données optiques, SZ et X et les profils radiaux de masse et de propriétés thermodynamiques de l’ICM sont mesurés en associant les données X et SZ. Cela permet de montrer que XLSSC102 est un amas en coalescence avec une masse de ∼ 3 × 10^14 Msol et est compatible avec le scénario d’évolution standard de la formation des amas. / Addressing fundamental questions regarding our understanding of the Universe, such as the cause of its accelerated expansion or the nature of dark matter, requires to confront theories and observations. In this context, galaxy clusters can be used as powerful observational probes. However, their current utilisation is limited by uncertainties and systematic effects, notably affecting the measurement of their mass, which is presumably dominated by dark matter.Galaxy clusters can be studied at different wavelengths: the hot gas composing the Intra Cluster Medium (ICM) shines in X-ray and is observable at millimetre wavelengths via the Sunyaev-Zel’dovich (SZ) effect, whereas galaxies emit principally in the optical and infrared. Combining and comparing these observables allows us to reduce the uncertainties and systematics in the cosmological constraints obtained from clusters. In this context, this thesis aims at paving the way of future large surveys such as Euclid and the Large Synoptic Survey Telescope. It presents the multi-wavelengths analyses of a sample of clusters detected in X-ray in the XXL survey, spanning a wide range of masses and redshifts. The first part of the thesis introduces the cosmological context and presents the observational properties of galaxies and clusters, and the ingredients to build cosmological cluster samples. The second part concentrates on the optical characterisation of XXL clusters and the properties of their member galaxies. It starts by presenting XXL and the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), an optical counterpart survey. Then, it focuses on the characterisation of the CFHTLS photometric redshifts quality and their use to construct the optical galaxy luminosity functions (LF) of XXL clusters. The LF of satellite galaxies is found to slightly depend on cluster richness, the main optical mass proxy, but no significant redshift evolution is observed. Then, the study of the colour and active galactic nuclei (AGN) fraction in XXL cluster galaxies is performed, finding that the mass plays a key role in shaping AGN and star formation activity in clusters. Finally, the WaZP optical cluster finder algorithm is used to investigate the optical counterparts of XXL clusters. The third part of this thesis is dedicated to the observational project dedicated to the mapping of the SZ signal in three distant XXL clusters, with the high angular resolution NIKA2 camera. The preparation of the project is discussed, making use of the X-ray and optical data to predict the expected SZ signal. Then, the observation procedure at the telescope and the data reduction, dedicated to produce calibrated SZ maps, are presented. The project is still ongoing and one cluster, XLSSC102, at z = 0.97, has been partially observed. The development of the blind detection of galaxies potentially contaminating the SZ signal is developed, allowing for the serendipitous discovery of dusty star forming galaxies in the field of XLSSC102. The morphology and dynamical state of XLSSC102 are then characterised using optical, SZ and X-ray data and the radial ICM thermodynamics and mass profiles are measured combining SZ and X-ray data. This allows us to show that XLSSC102 is a merging cluster with a mass ∼ 3 × 10 14 M, and is compatible with the standard evolution scenario of cluster formation.