513 research outputs found
Transport of ultracold atoms between concentric traps via spatial adiabatic passage
Spatial adiabatic passage processes for ultracold atoms trapped in
tunnel-coupled cylindrically symmetric concentric potentials are investigated.
Specifically, we discuss the matter-wave analogue of the rapid adiabatic
passage (RAP) technique for a high fidelity and robust loading of a single atom
into a harmonic ring potential from a harmonic trap, and for its transport
between two concentric rings. We also consider a system of three concentric
rings and investigate the transport of a single atom between the innermost and
the outermost rings making use of the matter-wave analogue of the stimulated
Raman adiabatic passage (STIRAP) technique. We describe the RAP-like and
STIRAP-like dynamics by means of a two- and a three-state models, respectively,
obtaining good agreement with the numerical simulations of the corresponding
two-dimensional Schr\"odinger equation.Comment: 13 pages, 6 figure
Flexible system of multiple RGB-D sensors for measuring and classifying fruits in agri-food Industry
The productivity of the agri-food sector experiences continuous and growing challenges that make the use of innovative technologies to maintain and even improve their competitiveness a priority. In this context, this paper presents the foundations and validation of a flexible and portable system capable of obtaining 3D measurements and classifying objects based on color and depth images taken from multiple Kinect v1 sensors. The developed system is applied to the selection and classification of fruits, a common activity in the agri-food industry. Being able to obtain complete and accurate information of the environment, as it integrates the depth information obtained from multiple sensors, this system is capable of self-location and self-calibration of the sensors to then start detecting, classifying and measuring fruits in real time. Unlike other systems that use specific set-up or need a previous calibration, it does not require a predetermined positioning of the sensors, so that it can be adapted to different scenarios. The characterization process considers: classification of fruits, estimation of its volume and the number of assets per each kind of fruit. A requirement for the system is that each sensor must partially share its field of view with at least another sensor. The sensors localize themselves by estimating the rotation and translation matrices that allow to transform the coordinate system of one sensor to the other. To achieve this, Iterative Closest Point (ICP) algorithm is used and subsequently validated with a 6 degree of freedom KUKA robotic arm. Also, a method is implemented to estimate the movement of objects based on the Kalman Filter. A relevant contribution of this work is the detailed analysis and propagation of the errors that affect both the proposed methods and hardware. To determine the performance of the proposed system the passage of different types of fruits on a conveyor belt is emulated by a mobile robot carrying a surface where the fruits were placed. Both the perimeter and volume are measured and classified according to the type of fruit. The system was able to distinguish and classify the 95% of fruits and to estimate their volume with a 85% of accuracy in worst cases (fruits whose shape is not symmetrical) and 94% of accuracy in best cases (fruits whose shape is more symmetrical), showing that the proposed approach can become a useful tool in the agri-food industry.This project has been supported by the National Commission for Science and Technology Research of Chile (Conicyt) under FONDECYT grant 1140575 and the Advanced Center of Electrical and Electronic Engineering - AC3E (CONICYT/FB0008)
Una altra educació per a un altre desenvolupament a través de la cooperació i de la solidaritat internacional
Abstract not availabl
UDWDM-PON using low-cost coherent transceivers with limited tunability and heuristic DWA
A new Passive Optical Network (PON)
for access, making use of Ultra Dense Wavelength
Division Multiplexing (UDWDM) by densely spacing
channels at few GHz, and introducing the
“wavelength-to-the-user” concept, is proposed. The
key challenge will be developing low-cost coherent
transceivers, providing an excellent selectivity while
avoiding filters, and furnishing high sensitivity,
which will allow high splitting ratios, large number
of users and long distance reach. The Optical
Distribution Network (ODN) at the outside plant is
based on splitters and kept compatible with legacy
systems. Optical Network Unit (ONU) designs
realized with coherent transceivers using one or two
lasers are presented and the corresponding Optical
Line Terminal (OLT) architectures are introduced.
The ONUs at customer premises own lasers with
limited thermal tunability and their wavelengths are
randomly distributed in a band. By using heuristic
Dynamic Wavelength Assignment (DWA) schemes and
extending the original working band, the required
optical band is obtained and optimized. In activation
processes, ONU acceptances up to 99.9% are achieved.
Furthermore, in operation scenario under indoors
and also under outdoors environmental conditions,
ONU blocking probabilities below 0.1% and ONU
availability ratios (OARs) up to 99.9% are
demonstrated. The PON is dimensioned according to
the number of deployed users and system reach;
moreover, power safety and also fiber nonlinearities
constraints are evaluated, illustrating the
characteristics of the projected network. Finally, the
coexistence with legacy networks is discussed.Peer ReviewedPostprint (author's final draft
Sobre l'amor i la mort
Treballs Finals de Grau de Belles Arts. Facultat de Belles Arts. Universitat de Barcelona, Curs: 2019-2020, Tutor: Vila Pou, Eva[cat] Aquest projecte neix amb la intenció de recuperar un imaginari esborrat, pel pas del temps, de les memòries de qui el visqué. Un diàleg entre l'arxiu personal i un de familiar, separats entre ells per tres salts generacionals. Aquest arxiu apropiat s'utilitza com a llavor per a llaurar el que esdevé una reinterpretació dels records de qui capturà aquelles vivències. Tot això, prenent com a principi la idea de reutilitzar l'arxiu fotogràfic que ha evitat l'oblit d'aquells moments.[eng] This project was conceived with the intention of recovering an imaginary which, through the passage of time, had been lost from the memories of those who lived it. A dialogue between the personal archive and a family one, separated by three generations. This appropriated archive is used as a seed to cultivate what becomes a reinterpretation of the memories of those who captured those experiences. All of this, taking for a principle the idea of reusing the photographic archive which has kept those moments from being forgotten
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