Ce mémoire présente la modélisation théorique de l'expérience FORCA-G (FORce de CAsimir et Gravitation à courte distance) actuellement en cours de développement à l'Observatoire de Paris. L'objet de cette expérience est la mesure des interactions à courte portée entre un atome et une surface massive. Les interactions recherchées sont du type électrodynamique quantique (effet Casimir-Polder) et gravitationnelle. Le travail présenté ici a consisté à calculer les états des atomes dans le contexte de l'expérience afin de prévoir les signaux et les performances de l'expérience. Ceci a permis l'optimisation du schéma expérimental pour la mesure à la fois de l'effet Casimir-Polder à une précision non encore atteinte ainsi que pour la recherche de déviations à la loi de Newton prédites par les théories d'unification.

An accurate and generalized global retrieval algorithm from satellite observations is a prerequisite to understand the radiative effect of atmospheric aerosols on the climate system. Current operational aerosol retrieval algorithms are limited by the inversion schemes and suffering from the non-uniqueness problem. In order to solve these issues, a new algorithm is developed for the retrieval of non-spherical dust aerosol over land using multi-angular radiance and polarized measurements of the POLDER (POLarization and Directionality of the Earth’s Reflectances) and wide spectral high-resolution measurements of the MODIS (MODerate resolution Imaging Spectro-radiometer). As the first step to account for the non-sphericity of irregularly shaped dust aerosols in the light scattering problem, the spheroidal model is introduced. To solve the basic electromagnetic wave scattering problem by a single spheroid, we developed an algorithm, by transforming the transcendental infinite-continued-fraction-formeigen equation into a symmetric tri-diagonal linear system, for the calculation of the spheroidal angle function, radial functions of the first and second kind, as well as the corresponding first order derivatives. A database is developed subsequently to calculate the bulk scattering properties of dust aerosols for each channel of the satellite instruments. For the purpose of simulation of satellite observations, a code is developed to solve the VRTE (Vector Radiative Transfer Equation) for the coupled atmosphere-surface system using the adding-doubling technique. An alternative fast algorithm, where all the solid angle integrals are converted to summations on an icosahedral grid, is also proposed to speed-up the code. To make the model applicable to various land and ocean surfaces, a surface BRDF (Bidirectional Reflectance Distribution Function) library is embedded into the code. Considering the complimentary features of the MODIS and the POLDER, the collocated measurements of these two satellites are used in the retrieval process. To reduce the time spent on the simulation of dust aerosol scattering properties, a single-scattering property database of tri-axial ellipsoid is incorporated. In addition, atmospheric molecule correction is considered using the LBLRTM (Line-By-Line Ra- diative Transfer Model). The Levenberg-Marquardt method was employed to retrieve all the interested dust aerosol parameters and surface parameters simultaneously. As an example, dust aerosol properties retrieved over the Sahara Desert are presented.

Polderiai labai paplitę hidrotechnikos statiniai Šilutės rajono teritorijoje. Jų paskirtis – užtikrinti teritorijų ir statinių apsaugą nuo patvenkimo bei apsėmimo. Šiame darbe nagrinėjama Alkos, Smalkų vasaros tipo ir Traksėdžių, Kintų, Rugulių žiemos tipo polderių hidrotechnikos statinių būklė. Tyrimų metu buvo nustatyta, kad dėl nešmenų sankaupų sausinamuosiuose grioviuose, jų dugno altitudės pakilusios (nešmenų sluoksnio storis siekia 0,2 – 1,0 m). Pylimų šlaituose (100 m ruože) aptinkami iki 10 graužikų urvų ar jų įgriuvos. Griovių šlaituose ir apsauginėse juostose paplitusios aukštaūgės augmenijos juostos, kurių plotai 100 m ilgio pakrantės ruože siekia 60 m2. Aiškiai matomos griovių šlaitų tvirtinimo gelžbetoninių elementų pažaidos. Tarp deformuotų, paplautų ir pasislinkusių tvirtinimo plokščių susidarę 2 – 11 cm tarpai. Važiuojamųjų pylimų keterose ties pralaidomis dėl įsiurbto grunto susidariusios 0,2 – 0,4 m įdubos. Tenkinant gamtosaugininkų reikalavimus vandens lygis vasaros tipo polderių kanaluose palaikomas nuo 0,5 iki 1,1 m aukštesnis, palyginus su eksploataciniais vandens lygiais, reikalingais sėkmingai ūkinei veiklai vystyti. Atlikta vandens lygių stebėjimo duomenų analizė, aptarti gamtosauginiai ir eksploataciniai vandens lygiai polderiuose. Sugretinus nustatytus duomenis, įvertinti minėtų lygių dydžiai atitinkamo laikotarpio/periodo metu. Remiantis gautais rezultatais, pateiktas realus, konkretus ir teigiamų rezultatų suteiksiantis pasiūlymas, t.y... [toliau žr. visą tekstą] / Polders are very common hydrotechnical structures in Šilutė district. Their purpose is to protect its territories and structures from flooding. This paper examines the condition of the summer-type polder hydrotechnical structures of Alka and Smalkai, as well as the winter-type polder hydrotechnical structures of Traksėdžiai, Kintai and Ruguliai. During the research it was established that the accumulation of sediment in drainage ditches increases their bottom altitudes (the thickness of the sediment layer amounts to 0.2-1,0 m). The slopes of the dykes (in the distance of 100 metres) contains up to 10 inhabited or fallen-in rodent caves. The trench slopes and protective zones are overgrown with tall vegetation, the area of which in 100 m of the bank strip amounts to 60 m2. The damage of the reinforced mounting elements of the ditch slopes is clearly visible. The spaces between deformed, washed and shifted mounting plates are 0.5-11 cm. Slumped ground along the culverts in the carriageway resulted in deeper than 0.2-0.4 m cavities. Meeting the environmental requirements, the water level in the summer-type polder channels maintained is 0.5-1.1 m higher, compared to the operational water levels required for successful agricultural activity. The paper includes a water level monitoring data analysis and a discussion of the environmental and operational water levels in polders. Data comparison allowed to evaluate the values of the above-mentioned levels at relevant... [to full text]

Frequent floods of the Bečva River with increasingly more dramatic progress represent a growing threat to the region. The high cost of the solution is connected with it. This fact makes every reasonable individual think of how to prevent the floods or at least mitigate the effects on inhabitants´ lives, the regional economy and the natural environment. In 1997, there was almost no effective way to warn and protect inhabitants against the sudden arrival of flood waters. The absence of these measures kick-started changes in the field of crisis management. Although the floods of 2006 did not impact the area I am dealing with, they have definitely revealed the effectiveness and the positive trends of safety measures in population protection development. More dramatic flooding of the Becva River in 2010, tested the preparedness of not only the flood authorities, IZS (Emergency and Rescue Services), but practically all the region's inhabitants. The aim of this work is to discover if the 1997 floods started adequate flood control construction in the region, their current state and future plans. I would like to present and compare three of the most interesting studies concerning the Bečva river flood controls.

The diploma thesis focuses on problematics connected to the flood and individual kinds of anti-flooding measures in agriculturally used landscape. Theoretical part of the thesis is devoted to the general description of flood problematic. It contains basic terms connected with floods, mentions causes and flood categories, and also the factors that influence it's progress. Thesis includes precautions and solutions of the anti-flood protection. In the practical part of the thesis is characterised chosen region with flood risk. Analysis of the present state includes field research. As a result of the discovered risks have been selected appropriate anti-flood measures for stated location.

Aerosols contribute the largest uncertainty to estimates of radiative forcing of the Earth’s atmosphere, which are thought to exert a net negative radiative forcing, offsetting a potentially significant but poorly constrained fraction of the positive radiative forcing associated with greenhouse gases. Aerosols perturb the Earth’s radiative balance directly by absorbing and scattering radiation and indirectly by acting as cloud condensation nuclei, altering cloud albedo and potentially cloud lifetime. One of the major factors governing the uncertainty in estimates of aerosol direct radiative forcing is the poorly constrained aerosol single scattering albedo, which is the ratio of the aerosol scattering to extinction. In this thesis, I describe a new instrument for the measurement of aerosol optical properties using photoacoustic and cavity ring-down spectroscopy. Characterisation is performed by assessing the instrument minimum sensitivity and accuracy as well as verifying the accuracy of its calibration procedure. The instrument and calibration accuracies are assessed by comparing modelled to measured optical properties of well-characterised laboratory-generated aerosol. I then examine biases in traditional, filter-based absorption measurements by comparing to photoacoustic spectrometer absorption measurements for a range of aerosol sources at multiple wavelengths. Filter-based measurements consistently overestimate absorption although the bias magnitude is strongly source-dependent. Biases are consistently lowest when an advanced correction scheme is applied, irrespective of wavelength or aerosol source. Lastly, I assess the sensitivity of the direct radiative effect of biomass burning aerosols to aerosol and cloud optical properties over the Southeast Atlantic Ocean using a combination of offline radiative transfer modelling, satellite observations and global climate model simulations. Although the direct radiative effect depends on aerosol and cloud optical properties in a non-linear way, it appears to be only weakly dependent on sub-grid variability.

Different types of man-made retention systems (polder, small water reservoir, large water reservoir) have been characterized by means of their retention potential and cost of retention per one cubic meter. As part of these man-made retention systems, wetland area has been created. Its acreage and build expense has been counted up inreference to total area, which differed within various types of retention systems. The results of these calculations, Hessenian method, and the metohod of agricultural land use were used to evaluate natural river basin and its retention potential. The calculations reveal, that model locality of natural river basin has the lowest value, when used for agriculture cultivation. Hessenian method showed the highest value. The expense of substituting the natural retention of the model locality with different man-made retention systems is estimated to be 0.5?1.6 billion CZK.

Le travail présenté dans ce manuscrit porte sur l'avancement de l'expérience FORCA-G (FORce de CAsimir et Gravitation à courte distance) dont le but est la mesure par interférométrie atomique de forces à courte distance entre un atome, piégé dans un réseau optique vertical, et une surface. Réalisée à l'aide de transitions Raman stimulées, la séparation spatiale et cohérente des paquets d'onde atomique sur des puits adjacents du réseau permet de mesurer, après recombinaison, la différence d'énergie entre ces puits, liée à l'incrément d'énergie potentielle de pesanteur : la fréquence de Bloch nB. Pour de faibles densités atomiques, il est démontré une sensibilité court terme à 1 s de dn/nB = 1,8.10-6 à l'état de l'art des capteurs de forces à atomes piégés. La mise en place d'un système de refroidissement évaporatif, afin d'augmenter le nombre d'atomes par puits, permet désormais d'explorer des régimes de fortes densités atomiques où les interactions ne peuvent être négligées. Pour des densités de 1011-1012 at/cm3, il est montré qu'un phénomène d'auto-synchronisation des spins entre en compétition avec le mécanisme d'écho de spin. L'impact de ce phénomène sur le contraste et la fréquence mesurée est étudié dans un interféromètre où les deux paquets d'onde occupent le même puits. Des premières mesures sont ensuite effectuées dans le régime où les paquets d'onde sont séparés. Elles montrent un comportement différent qui reste à modéliser. Enfin, il est montré que le protocole de mesure permet de s'affranchir des biais collisionnels : les interactions atomiques limitent la sensibilité du capteur de force sans limiter son exactitude. / This thesis presents the recent progress on the FORCA-G (FORce de CAsimir et Gravitation à courte distance) experiment which aims at measuring short range forces between an atom, trapped in a vertical optical lattice, and a mirror. Stimulated Raman transitions are used to induce coherent transport between adjacent lattice sites to perform atom interferometry in order to measure with very high sensitivity, shifts in the Bloch frequency nu_B, which is the potential increment between two lattice sites. For low atomic densities, we demonstrate a local force sensor with state-of-the art relative sensitivity on the Bloch frequency of deltanu/nu_B= 1.8x10-6 at 1 s. The recent use of evaporative cooling, in order to increase the number of atoms per well, allows to work the experiment with much denser atomic clouds where atom interactions cannot be neglected. At densities of 1011-1012 at/cm3, it is shown that a spin self-rephasing mechanism competes with the spin-echo technique. The impact of the former mechanism onto the contrast and the measured frequency is studied in an interferometer where the two partial wave packets perfectly overlap. First measurements are then performed in a regime where the two partial wave packets are spatially separated. They show a different behaviour that remains to be modelled. Finally, it is shown that the measurement protocol allows to greatly reduce collisional shifts: atom interactions limit the sensitivity of the local force sensor without limiting its accuracy.

This thesis deals with the flood control. In particular, the design of a set of small water reservoirs with retention effect (polders) and their effect on flood flows. The work is divided into two parts, the first part refers to the bachelor thesis. In this thesis is description of the catchment, rainfall-runoff process and the evaluation of the ratio. That was got the necessary information for the design of polders. This is an abbreviated repetition of the contents of the thesis, which is a continuation of this work. The second part deals with the specific design of two reservoirs, including hydro calculations and drawings. For this work were used ArcGIS - ArcMap, Hydrog and to create drawings AutoCAD 2010.

Depuis plusieurs décennies un intérêt est né pour combiner deux systèmes quantiques pour former unsystème hybride quantique (SHQ) aux qualités qu’il serait impossible d’atteindre avec un seul des deuxsous-constituants. Parmi les systèmes quantiques, les atomes froids se distinguent par leur fort découplagede l’environnement, permettant un contrôle précis de leurs propriétés intrinsèques. En outre, les simulateursquantiques réalisés en piégeant des atomes froids dans des réseaux optiques présentent des propriétéscontrôlables (échelle d’énergie, géométrie,...) qui permettent d’étudier de nouveaux régimes intéressants enphysique de la matière condensée. Dans cette quête de phases quantiques exotiques (e.g., antiferromagnétisme),la réduction de l’entropie thermique est un défi crucial. Le prix à payer pour atteindre de si faiblestempérature et entropie est un long temps de thermalisation qui limite la réalisation expérimentale. La réductionde la période du réseau est une solution prometteuse pour augmenter la dynamique du système.Les SHQs avec des atomes froids offrent de riches perspectives mais requiert d’interfacer des systèmes quantiquesdans des états différents (solide/gaz) à des distances très proches, ce qui reste un défi expérimental.Le projet AUFRONS, dans lequel s’inscrit cette thèse, vise à refroidir un gaz d’atomes froids jusqu’aurégime de dégénérescence quantique puis de transporter et piéger ce nuage en champ proche d’une nanostructure.L’idée est d’obtenir un gaz d’atomes froids piégé dans un réseau bidimensionnel aux dimensionssublongueur d’onde, à quelques dizaines de nm de la structure. Un des objectifs est d’étudier les interactionsau sein du réseau mais également le couplage des atomes avec les modes de surface.Le travail réalisé durant cette thèse se décompose en une partie expérimentale et une partie théorique.Dans la première nous présentons le refroidissement d’atomes de 87Rb jusqu’au régime de dégénérescencequantique. La seconde partie est consacrée aux simulations théoriques d’une nouvelle méthode que nousavons implémentée pour piéger et manipuler des atomes froids à moins de 100 nm d’une nanostructure.Cette méthode, qui tire profit de la résonance plasmonique et des forces du vide (effet Casimir-Polder),permet de créer des potentiels sublongueur d’onde aux paramètres contrôlables. Nous détaillons ainsi lescalculs des forces optiques et des forces du vide que nous appliquons au cas d’un atome de 87Rb en champproche d’une nanostructure 1D. / An interest for hybrid quantum systems (HSQs) has been growing up for the last decades. This object combines two quantum systems in order to take advantage of both systems’ qualities, not available withonly one. Among these quantum systems, ultracold atoms distinguish themselves by their strong decoupling from environment which enables an excellent control of their intrinsic properties. Optical lattice quantum simulators with tunable properties (energy scale, geometry,...) allows one to investigate new regimes incondensed matter physics. In this quest for exotic quantum phases (e.g., antiferromagnetism), the reduction of thermal entropy is a crucial challenge. The price to pay for such low temperature and entropy is a longthermalization time that will ultimately limit the experimental realization. Miniaturization of lattice spacingis a promising solution to speed up the dynamics. Engineering cold atom hybrids offers promising perspectives but requires us to interface quantum systems in different states of matter at very short distances, which still remains an experimental challenge.This thesis is part of the AUFRONS project, which aims at cooling down an atomic gas until the quantum degeneracy regime then transport and trap this cloud in the near field of a nanostructure. The idea is to trapcold atoms in a two-dimensional subwavelength lattice, at a few tenth of nm away from the surface. One goal is to study atom-atom interactions within the lattice but also atom-surface modes coupling.The work realized during this thesis splits into an experimental part and a theoretical part. In the firstone, we present the cooling of 87Rb atoms until the quantum degeneracy regime. The second part is dedicated to theoretical simulations of a new trapping method we have implemented to trap and manipulate cold atoms below 100 nm from structures. This method takes advantage of plasmonic resonance and vacuum forces (Casimir-Polder effect). It allows one to create subwavelength potentials with controllable parameters.We detail the calculations of optical and vacuum forces to apply them to an atom of 87Rb in the vicinity of a 1D nanostructure.