Dissertations / Theses on the topic 'Lattice tray'

Досліджено характеристики вловлювання тонкодисперсого пилу та утворення відкладень накипу на зрошуваних ґратчастих та дiрчастих протитечійних (провальних) тарілках з великою перфорацією. Знайдено, що ступень вловлювання полідисперсного пилу з медіанним розміром часток 23 мкм на гратчастих тарілках дещо вищий ніж на дірчастих. Ступень очистки газу найбільш залежить від швидкості газу у повному перерізі апарату і має максимум в діапазоні 1,5 – 2,0 м/с, який становить 99,8 % при частці вільного перетину тарілок 15 % та зменшується до 99,2 при вільному перетині 35 %. Істотного впливу зрошення на досліджуваний параметр не виявлено. Дослідження утворення накипу показали, що найбільший вплив на швидкість утворення відкладень на тарілках мають концентрація гідрокарбонату кальцію та температура. Менший, але помітний вплив мають також швидкість газу та густина зрошення. Для усіх знайдених залежностей отримані апроксимаційні рівняння.
The characteristics of capture fine dust particles and formation of scale deposits on irrigated lattice and hole counter-current trays with a large perforation are investigated. It was found that the capture stage of a polydisperse dust with a median particle size of 23 μm on lattice plates is somewhat higher than that of the hole. The gas purification stage most depends on the gas velocity in the free section of the apparatus and has a maximum in the range of 1.5 - 2.0 m / s, which is 99.8% with a free section of the plates 15% and decreases to 99.2 with a free intersection 35%. Significant influence of irrigation on the investigated parameter was not detected. Investigations on the formation of scale have shown that the greatest influence on the rate of formation of sediment deposits on the plates has the concentration of calcium bicarbonate and temperature. Smaller but also noticeable effects have the speed of gas and irrigation density. Approximation equations are obtained for all the dependences found.

We investigate the diffusion of particles on heterogeneous lattices with two kinds of nonequivalent sites. General analytical expressions for the chemical and jump diffusion coefficients have been derived in the case of strong inhomogeneity. We have calculated coverage dependencies of the diffusion coefficients and other necessary thermodynamic quantities for some representative values of the lateral pairwise interaction between the particles. The analytical data have been compared with the numerical data obtained by the kinetic Monte Carlo simulations. Almost perfect agreement between the respective results has been found.

We investigate the diffusion of particles on heterogeneous lattices with two kinds of nonequivalent sites. General analytical expressions for the chemical and jump diffusion coefficients have been derived in the case of strong inhomogeneity. We have calculated coverage dependencies of the diffusion coefficients and other necessary thermodynamic quantities for some representative values of the lateral pairwise interaction between the particles. The analytical data have been compared with the numerical data obtained by the kinetic Monte Carlo simulations. Almost perfect agreement between the respective results has been found.

Lo studio effettuato ha lo scopo di confrontare un’ala per impiego aerospaziale o automotive con configurazione convenzionale e una con riempimento con struttura di tipo lattice regolare cubica non conforme, al fine di determinare se un’ala ottenuta mediante stampa con tecniche di additive manufacturing è in grado di competere con un’ala ottenuta attraverso metodi convenzionali a livello di massa a parità di sollecitazione massima. Il confronto è stato effettuato sia a pari peso calcolando le massime tensioni, sia ad equivalenti sollecitazioni esterne, andando a verificare i pesi ottenuti. A tale scopo è stata impiegata una analisi 1-way FSI che coinvolge sia simulazioni CFD che FEM. È stato anche messo in pratica un approccio di analisi semplificativo che consiste nello studiare la struttura lattice come se fosse un materiale continuo, cercando di capire se il cosiddetto metodo di omogeneizzazione applicato al caso di studio in questione, permette di ottenere risultati soddisfacenti riducendo di gran lunga i tempi di calcolo.

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 57-58).
We experimentally realize a magneto-optical trap (MOT) for ytterbium that simultaneously scatters light from two atomic transitions, in order to reduce the minimum magnetic field gradient required for trapping atoms. From the experimental data, we propose a model of the MOT where one transition is responsible for trapping the atoms the other transition is responsible for cooling the atoms. In order to test this model and to better understand the dynamics of this two-color MOT, we perform numerical simulations of the contributions of each transition to the steady-state number of trapped atoms. We then compare the results of the simulations with the experimental results and conclude that the model of the separated trapping and cooling functions is a good model for the two-color MOT. Finally, we examine other elements for which the two-color MOT is possible and derive a condition for the linewidths of the two transitions such that the atoms are trapped.
by QinQin Yu.
S.B.

The quantum properties of matter waves, in particular quantum correlations and entanglement are an important frontier in atom optics with applications in quantum metrology and quantum information. In this thesis, we report the first observation of sub-Poissonian fluctuations in the magnetization of a spinor 87Rb condensate. The fluctuations in the magnetization are reduced up to 10 dB below the classical shot noise limit. This relative number squeezing is indicative of the predicted pair-correlations in a spinor condensate and lay the foundation for future experiments involving spin-squeezing and entanglement measurements. We have investigated the limits of the imaging techniques used in our lab, absorption and fluorescence imaging, and have developed the capability to measure atoms numbers with an uncertainly < 10 atoms. Condensates as small as ≈ 10 atoms were imaged and the measured fluctuations agree well with the theoretical predictions. Furthermore, we implement a reliable calibration method of our imaging system based on quantum projection noise measurements. We have resolved the individual lattice sites of a standing-wave potential created by a CO2 laser, which has a lattice spacing of 5.3 µm. Using microwaves, we site-selectively address and manipulate the condensate and therefore demonstrate the ability to perturb the lattice condensate of a local level. Interference between condensates in adjacent lattice sites and lattice sites separated by a lattice site are observed.

Dopo l’analisi delle modalità di misurazione del potere di mercato e della competizione tra brand nel contesto di un mercato caratterizzato dalla presenza di prodotti differenziati, viene presentata l’applicazione dei modelli a scelta discreta nel mercato del latte alimentare in Italia. Ho utilizzato dati scanner per analizzare i comportamenti nelle scelte di acquisto dei consumatori e le dinamiche competitive tra i due maggiori brand presenti nel mercato e le marche commerciali. Ho considerato il mercato del latte alimentare suddiviso in due sottocategorie, quella del latte a lunga conservazione (UHT) e quella del latte refrigerato. Ho quindi proceduto alla stima della domanda del latte alimentare utilizzando un nested logit model, appartenente alla categoria dei modelli a scelta discreta. Utilizzando i coefficienti stimati è possibile sia calcolare le elasticità di sostituzione tra i diversi brand e le elasticità dirette, nonché i margini di profitto dei brand presi in analisi considerando differenze nelle strategie di prezzo e nella struttura di mercato.
This work first gives an overview of the measurement of market power and brand competition in a differentiated products market, secondly applies discrete choice models to asses the Italian milk market. I use scanner data to estimate consumer purchasing decisions and competitive relationships between two major industry-level brands and (as a third category) supermarket private labels. I divide all milk sold in Italian market into two distinct classes of products: “UHT” and “Refrigerated” milk. I employ a well-known “discrete choice” nested-logit model to estimate consumer demand. Then, using the estimated coefficients, it is possible to calculate both consumer substitution patterns between products, and the profit-margins of the three major retail-level brands across the different sub-categories of milk under different pricing strategies and market structure.

Condizioni meteorologiche e clima influenzano fortemente il settore delle produzioni animali. Lo stress da caldo determina una significativa riduzione dell'attività metabolica, della produzione, della capacità riproduttiva e una maggiore predisposizione alle malattie. Nel contesto biologico, la temperatura dell’aria è sicuramente considerata il principale fattore di stress, tuttavia, un’elevata umidità peggiora l'effetto della temperatura riducendo le perdite di calore per evaporazione e ostacolando quindi l’eliminazione del calore in eccesso. Scopi principali della ricerca sono stati la caratterizzazione dell’area del Mediterraneo in termini di Temperature Humidity Index (THI) e stabilire le relazioni tra stagione/THI e mortalità nella bovina da latte allevata in un’area geografica Italiana altamente vocata per questo tipo di allevamento. I risultati suggeriscono che, allevatori e politici che operano nell’area Mediterranea, dovrebbero tenere nella dovuta considerazione variabilità e scenari del THI nella pianificazione degli investimenti nel settore delle produzioni animali. Conoscere in anticipo il verificarsi di condizioni climatiche avverse permetterebbe agli allevatori di metter in atto misure di contrasto sugli effetti negativi delle condizioni climatiche. Inoltre, dovrebbero venire sviluppate misure di adattamento appropriate per contesti specifici in termini di cultura, società, o sistemi politici, che possano contribuire alla sostenibilità ambientale, nonché allo sviluppo economico e alla lotta alla povertà.
Weather and climate strongly influence the field of animal production. Heat stress causes a significant reduction in metabolic activity, production, reproductive capacity, and increases susceptibility to diseases. In the biological context, the air temperature is definitely considered the main factor of stress, however, high humidity worsens the effect of temperature by reducing the evaporation heat loss and thus preventing the removal of excess heat. The main purposes of the research were the characterization of the Mediterranean basin in terms of Temperature Humidity Index (THI) and to establish relationships between season/THI and mortality in dairy cattle bred in an Italian geographic area with a high concentration of dairy farms. THI variability and scenarios should be taken into careful consideration by farmers and policy makers operating in Mediterranean countries when planning investments. Investments should at least partially be directed to implementation of adaptation measures, which may support farmers in the transition to climate-smart agriculture and help them to alleviate the impact of hot extremes on animal welfare, performance and health. In addition, measures should be developed appropriate adaptation to the specific contexts in terms of culture, society, or political systems, which can contribute to environmental sustainability and economic development and fighting poverty.

Main topic of this Masters Thesis is design of railway station for high speed line railway. Building site is situated in East Moravian region in the district of Brno-Tuřany. The building is designed as a detached two-storey object standing on the bridge over the railway. Mass of the building consists of two trimmed blocks which are mutually mirrored. The mass of both parts of the building is pervaded by illuminating stripe. Its shape is also based on the shape of trimmed block and rises over the surrounding surfaces. There are placed vertical paths in the stripes. It helps passengers in orientation because these are visible even from the outside of the building. This arrangement of individual masses symbolizes both direction of the arrival of trains to the station. There is placed arrival and departure hall in the middle of the object. Its height is similar to the height of the object itself. The hall is surrounded by the service facilities of the railway station situated on two floors. The supporting structure is made of steel. Both peripheral housing and roof are supported by the frame construction consisting of planar lattice beams. Construction of the façade is composed of frame system Wicona. The peripheral housing is tiled with panels of expanded metal.

碩士
國立交通大學
應用數學系所
97
In this thesis, we would like to find out the stability of the solution which linearized around the special solution of the nonlinear Schrodinger equation. Here, we consider nonlinear Schrodinger equations with the potential part, optical lattices form and elliptic form. In the first part of the thesis, we introduce roughly the nonlinear Schrodinger equation and two kinds of trap potentials. Then, we show the mathematical analysis of the numerical method that we used. At the end, we give some numerical results of our numerical experience.

Laser beams with precisely controlled intensity profiles are essential for many areas. We developed a beam shaping system based on the digital micromirror device (DMD) for ultra-cold atom experiments and other potential applications. The binary DMD pattern was first designed by the error diffusion algorithm based on an accurate measurement of the quasi-Gaussian incident beam from a real-world laser. The DMD pattern was projected to the image plane by a bandwidth-limited 4f telescope that converted this pattern to the grayscale image. The system bandwidth determined the theoretical limit of image precision by the digitization error. In addition, it controlled the spatial shape of the point spread function (PSF) that reflected the tradeoff between image precision and spatial resolution. PSF was used as a non-orthogonal basis set for iterative pattern refinement to seek the best possible system performance. This feedback process, along with stable performance of DMD, the blue-noise spectrum of the error diffusion algorithm, and low-pass filtering, guaranteed high-precision beam shaping performance. This system was used to produce various beam profiles for different spatial frequency spectra. First, we demonstrated high-precision slowly-varying intensity beam profiles with an unprecedented high intensity accuracy. For flattop and linearly-tilted flattop beams, we achieved 0.20-0.34% root-mean-square (RMS) error over the entire measurement region. Second, two-dimensional sinusoidal-flattop beams were used to evaluate image precision versus system bandwidth. System evaluation confirmed that this system was capable of producing any spatial pattern with <3% RMS error for the most system bandwidth. This experiment extended the beam shaping to any system bandwidth and provided a reference to estimate the output image quality based on its spatial spectrum. Later experiment using a Lena-flattop beam profile demonstrated the arbitrary beam profile generation. We implemented this system for applications on the homogenous optical lattice and dynamic optical trap generation. The DMD pattern was optimized by the iterative refinement process at the image feedback arm, and projected through a two-stage imaging system to form the desired beam profile at the working plane. Experiments demonstrated a high-precision beam shaping as well as a fast and dynamic control of the generated beam profile.
text

Cold bosonic atoms trapped in optical lattices formed by standing wave interference patterns of multiple laser beams constitute excellent emulators of models of strongly correlated quantum systems of bosons. In this thesis, we develop and deploy strong-coupling expansion (i.e., an expansion in terms of the ratio of the inter-site hopping amplitude of the bosons to the strength of their interactions) techniques for studying the properties of three different instances of such systems. In the first instance, we have used strong coupling expansion techniques to calculate the density pro le for bosonic atoms trapped in an optical lattice with an overall harmonic trap at finite temperatures and large on site interaction in the presence of super fluid regions. Our results match well with quantum Monte Carlo simulations at finite temperature. We present calculations for the entropy per particle as a function of temperature which can be used to calibrate the temperature in experiments. Our calculations for the scaled density in the vacuum-to-super fluid transition agree well with the experimental data for appropriate temperatures. We also discuss issues connected with the demonstration of universal quantum critical scaling in the experiments. Experimental realizations of “atomtronic" Josephson junctions have recently been created in annular traps in relative rotation with respect to potential barriers that generate the weak links. If these devices are additionally subjected to optical lattice potentials, then they can incorporate strong-coupling Mott physics within the design, which can modify the behaviour and can allow for interesting new configurations of system generated barriers and of super fluid ow patterns. we have examined theoretically the behavior of a Bose super fluid in an optical lattice in the presence of an annular trap and a barrier across the annular region which acts as a Josephson junction. As the fluid is rotated relative to the barrier, it generates circulating super-currents until, at larger speeds of rotation, it develops phase slips which are typically accompanied by vortices. We use a finite temperature strong-coupling expansion about the mean- held solution of the Bose Hubbard model to calculate various properties of the device. In addition, we discuss some of the rich behavior that can result when there are Mott regions within the system. Rubidium-Cesium dipolar molecule formation through Feshbach resonance is an area of great current interest, for, the dipolar molecules, once formed, interact via v long range dipolar forces, leading to possibilities of novel phases. Experimentalists currently make such systems mostly using trial and error, and the resulting efficiencies for molecule formation tend to be low. With a goal to assist cold-atom experimentalists to achieve higher e ciencies of molecule formation, we have estimated the trap parameters for Rb and Cs atoms in a 3D optical lattice required to create single occupancy per site Mott phase for both the species in the same regions of the trap. We thus identify the ne tuning of the external magnetic held near Rb-Cs Feshbach resonance required to achieve highest probability for creating single Rb-Cs Feshbach molecules in the system. We have used the Falicov-Kimball model to describe the relevant system and strong-coupling expansions about the mean- held solution to calculate the density pro les for both species and efficiency for molecule formation, determined by overlapping regions of single occupancy for both Rb and Cs, up to second order in the expansion. We also calculate the entropy per particle which serves as an estimation of the temperature in the experimental system

Rozprawa omawia wybrane zastosowania metrologiczne zimnych atomów pułapkowanych optycznie na przykładzie dwóch eksperymentów: pułapki dipolowej dla zimnych atomów rubidu oraz sieci optycznej dla atomów strontu, będącej częścią większego przedsięwzięcia: pierwszego polskiego atomowego zegara optycznego. Optyczna pułapka dipolowa dla atomów rubidu powstała w laboratorium Zimnych Atomów Zakładu Fotoniki Uniwersytetu Jagiellońskiego. Celem budowy nowego stanowiska eksperymentalnego jest możliwości badania nieliniowych efektów magnetooptycznych, jak na przykład efekt Fardaya do celów precyzyjnej magnetometrii. W pierwszym etapie atomy rubidu są chłodzone w dwuwymiarowej pułapce magneto-optycznej (2D-MOT), formując strumień wstępnie schłodzonych atomów dla trójwymiarowej pułapki magnetooptycznej (3D-MOT). Proces przeładowania i formowania wiązki i jest szczegółowo opisany i scharakteryzowany.Następnie zimne atomy są do pułapki optycznej dipolowej (ODT), która przestrzennie przekrywa się z 3D-MOT. Rozprawa opisuje wyniki badania efektu Faradaya w optycznej pułapce dipolowej. Sieć optyczna dla atomów strontu jest częścią budowy Polskiego Optycznego Zegara Atomowego (POZA) w Krajowym Laboratorium Fizyki Atomowej, Molekularnej i Optycznej. Szczegółowo opisana jest aparatura tworząca strontowy standard częstotliwości dla zegara atomowego. Omówione są wyniki badania spektroskopii ultra-wąskiego przejścia zegarowego w próbkach atomów Strontu oraz stabilności stworzonego na jego bazie zegara optycznego.
Two experiments with laser-cooled atoms held in an optical dipole traps are described in the dissertation. First is dedicated to non-linear magneto-optical effects in rubidium atoms, while second is devoted to optical lattice trap for strontium atoms. Selected metrological applications of optically trapped cold atoms in both experiments are discussed and presented. A dipole trap setup has been built at the Department of Photonics in Jagiellonian University. It is aimed at investigations of nonlinear magneto-optical effects like precise magnetometry by Faraday effect. A compact two-dimensional magneto optical (2D-MOT) trap with permanent magnets serves as a source of cold rubidium atoms for further cooling in three-dimensional magneto-optical trap (3D-MOT). The 2D-MOT is described and characterised. The results of the loading an optical dipole trap (ODT) from a the 3D-MOT are then presented. It is followed by the results of a Faraday rotation of a resonant laser beam with atoms confined in the final stage of confinement in ODT. The strontium lattice experiment is a part of a larger project: the construction of the first polish optical atomic clock (project Polish Optical Atomic Clock) at the National Laboratory for Atomic, Molecular and Optical Physics. An introduction to time and frequency metrology with optical clocks is given. We describe strontium atoms confined in the optical lattice as a frequency reference for the optical clock in detail. The results of precision spectroscopy of ultra- narrow clock transition in bosonic Sr-88 and the measurements of the clock stability based on atomic reference are presented and discussed.