Experimental investigation of quantum key distribution with position and momentum of photon pairs

We investigate the utility of Einstein-Podolsky-Rosen correlations of the position and momentum of photon pairs from parametric down-conversion in the implementation of a secure quantum key distribution protocol. We show that security is guaranteed by the entanglement between downconverted pairs, and can be checked by either direct comparison of Alice and Bob's measurement results or evaluation of an inequality of the sort proposed by Mancini et al. (Phys. Rev. Lett. 88, 120401 (2002)).Comment: 6 pages, 6 figures, subimitted for publicatio

A power management strategy for a stand-alone photovoltaic/fuel cell energy system for a 1kW application

In this paper a power management strategy is presented for a stand-alone photovoltaic (PV)/fuel cell (FC) energy system. PV is the primary power source of the system and an FC-electrolyzer combination is used as a backup and a long-term storage system. The energy in the hybrid system is balanced by the common dc bus voltage regulation. A simple hysteresis voltage control is used for dc bus voltage regulation. In this way, the fuel cell and the electrolyzer can be protected from unnecessary utilization or irregular operation (reduction of frequent start-ups and shutdowns). Simulation results obtained using Matlab and Simulink are presented to verify the effectiveness of the proposed control algorithm

Performance of a solar-hydrogen stand-alone system for residential applications

Hydrogen, as an energy storage medium, is considered a promising solution to overcome the limitation of intermittent renewable energy sources. In this paper, a residential scale solar-hydrogen based stand-alone energy system is designed, modelled and the simulated system performance under real end-use load, representative of standard European domestic electrical energy consumption, and meteorological conditions is analyzed. The sun is the primary energy source of the system and a fuel cell-electrolyzer combination is used as a backup and a long-term storage system. A battery bank is also used as energy buffer and for short time storage. Matlab/Simulink® is used for the overall system modelling and simulation. The results show that the designed solar-hydrogen system is in principle capable of operating autonomously and in a sustainable manner. The designed system is able to convert 7.6% of the total energy irradiated in one year

Analysis of the temperature influence on Langmuir probe measurements on the basis of gyrofluid simulations

The influence of the temperature and its fluctuations on the ion saturation current and the floating potential, which are typical quantities measured by Langmuir probes in the turbulent edge region of fusion plasmas, is analysed by global nonlinear gyrofluid simulations for two exemplary parameter regimes. The numerical simulation facilitates a direct access to densities, temperatures and the plasma potential at different radial positions around the separatrix. This allows a comparison between raw data and the calculated ion saturation current and floating potential within the simulation. Calculations of the fluctuation-induced radial particle flux and its statistical properties reveal significant differences to the actual values at all radial positions of the simulation domain, if the floating potential and the temperature averaged density inferred from the ion saturation current is used.Comment: Submitted to Plasma Physics and Controlled Fusio

Irrigação do cajueiro-anão-precoce na região de Teresina.

bitstream/CPAMN-2009-09/20953/1/CT186.pd

Avaliação de um plano de formação : o trabalho de campo no ensino da Geologia

Apresentam-se os resultados de uma avaliação de um plano de formação relativo ao trabalho de campo no ensino da geologia aplicado a seis professores de duas escolas secundárias de Vila do Conde, distrito do Porto, no Noroeste de Portugal. O estudo apresentado permite verificar o impacto positivo do plano de formação através da análise de snapshots (pequenos questionários) preenchidos pelos formandos e pelo formador no final de cada uma das cinco sessões que integraram a formação

On the dynamics of bubbles in boiling water

We investigate the dynamics of many interacting bubbles in boiling water by using a laser scattering experiment. Specifically, we analyze the temporal variations of a laser intensity signal which passed through a sample of boiling water. Our empirical results indicate that the return interval distribution of the laser signal does not follow an exponential distribution; contrariwise, a heavy-tailed distribution has been found. Additionally, we compare the experimental results with those obtained from a minimalist phenomenological model, finding a good agreement.Comment: Accepted for publication in Chaos, Solitons & Fractal

Aprendizaje – servicio en la Universidad Católica Portuguesa Viseu – experiencia piloto

Some of the concepts of Service Learning (SL) are common to the teaching of health-related areas. However, there are many other requisites for a project to be SL such as the developing of student’s commitment to contribute to society and the importance of reflection on the learning experience. In this presentation the application of the SL methodology to Health in the Centro Regional de Viseu of the Universidade Católica Portuguesa, where students from the Integrated Master of Dental Medicine as well as the Bachelors in Management get together to help a senior nursing home to improve the oral health of the residents and the financial management of the home. The project is only half completed so far and there are still goals to accomplish. However, students’ portfolios already show that the 51 students involved in treating about 200 elderly residents are happy to participate in the project. These students are working closely with the Home managers and employees to improve oral health and prevent oral diseases. This pilot intervention is part of a larger project which aims at implementing SL in the Universidade Católica Portuguesa as well as to identify good practices in SL in Portugal.Algunos de los conceptos de la Aprendizaje-Servicio (ApS) son comunes con la enseñanza de muchas de las áreas de la salud. Sin embargo, hay muchos otros requisitos que están presentes en ApS como la toma de conciencia de ser un actor en la resolución de problemas sociales y la reflexión sobre las experiencias de ApS. En esa contribución se presenta la aplicación de la metodología ApS en el Centro Regional de Viseu de la Universidade Católica Portuguesa, onde alumnos del Máster en Odontología e del Master en Gestión se juntarán para ayudar un Residência de Mayores a mejorar la Salud Oral de sus mayores e la gestión financiera la residencia de mayores. El proyecto está en la mitad, pero la satisfacción de los alumnos ya es evidente por el análisis reflexivo que hicieran en sus porfolios. Están involucrados 51 alumnos en ese proyecto, trabajando con la dirección y los auxiliares de esa institución que tiene casi 200 mayores en régimen de internamiento. Esa experiencia piloto es parte de un proyecto más largo que tiene como objetivo implementar la ApS en toda la Universidade Católica Portuguesa y crear un ejemplo de buenas prácticas en ApS en Portugal.info:eu-repo/semantics/publishedVersio