Vic va patir quatre bombardejos aeris entre el 21 de desembre de 1938 i l’1 de febrer de 1939. Aquest article analitza com s’havia preparat la ciutat davant un eventual atac aeri, com van ser els ...bombardejos i quines víctimes van provocar. L’article aprofundeix en el tema amb l’ús de moltes fonts, entre les quals destaca l’arxiu particular de l’arquitecte Manuel Gausa, vocal de la Junta Local de Defensa Passiva de Vic, que aporta nova informació sobre els refugis antiaeris i els llocs de Vic on van caure les bombes.
Coherent wavelength division multiplexing (WDM) technologies have leveraged the optical communication systems in core networks, increasing the fiber capacity by transmission with advanced modulation ...formats and mitigation of impairments with digital signal processing. However, these solutions are too expensive for access networks, where cost, power budget, and footprint are limited. Hence, the key technology will be developing low-cost coherent transceivers providing an excellent selectivity and giving high sensitivity, which allows high splitting ratios. This paper reports an experimental design of a low-cost coherent ultra-dense WDM passive optical network (UDWDM-PON) with 6.25 GHz channel spacing. The users’ optical network unit (ONU) is built employing coherent transceivers with two paired low-cost distributed feedback (DFB) lasers, one as the local oscillator and another as the transmitter, offering simplicity and low-cost hardware; likewise, the optical line terminal (OLT) at the central office can profit from the same design. The ONU DFB lasers have wavelengths with limited thermal tunability, controlled by a thermo-electric cooler, which is used to allocate the wavelengths. A medium access control (MAC) at the OLT manages the spectrum channel allocation for ONUs, demanding connection when activation is requested: the OLT furnishes an optical carrier wavelength for the ONU to obtain connection by a control algorithm, assigning a down-channel and another paired up-channel assigned to the ONU DFB transmitter. The MAC can reassign the channels because of interference or collision in a dynamic wavelength allocation. Measures in an activation process and in channel reassignment have been performed in environmental conditions, including control signals and the physical parameters of DFB lasers, demonstrating the practical viability of the PON scaling from 32 up to 256 wavelength channels.
El turismo LGBT se está consolidando como una importante actividad dentro del sector turístico. La ciudad de Barcelona no es ajena a esta tendencia. Sin embargo, la satisfacción obtenida con esta ...experiencia depende de diferentes variables según la motivación principal para realizar este viaje. En este artículo se analizan estos aspectos comparando los resultados de dos encuestas. La primera, a una muestra de los asistentes al Festival Circuit, y la segunda, a un grupo de turistas LGBT ajenos a este evento. De esta manera se ha confirmado que hay significativas diferencias entre la valoración dada por estos dos grupos de turistas a las diferentes variables que influyen en su viaje. El aspecto afectivo es el más valorado por los que realizan el viaje sin el reclamo de un gran evento pensado para este colectivo, aunque el componente lúdico tiene una gran influencia entre los asistentes a un macroevento pensado para el colectivo LGBT.
•We compare two low cost transmitters behaviour while they transmit 100km error-free.•We combine low driving voltage, lack of electrical amplification, 10G&colourless ONUs.•We examine the use of ...dispersion compensation and electronic equalization techniques.
An extensive experimental research of an optical access network behaviour has been realized, in the framework of studying distance enhancement of long reach passive optical networks (PONs), while maintaining low cost and high performance. The network system has been implemented with low cost transmitters – operated at low driving voltage, without the use of electrical amplification, at 10Gb/s – and with colourless optical network units (ONUs) as receivers. Although studied for variable lengths, error-free transmission (target bit-error rate at 10−9) over 100km reach has been achieved in several ways. The performance of extended PONs, when low cost transmitters operated at low driving voltage are utilized, is improved by the application of optical dispersion compensation and electronic equalization techniques. The chirp of the transmitter has been shown to have an important effect on the behaviour of the system because of the dispersion phenomenon. It is observed however, that the combined use of optical dispersion compensation and electronic equalization gives a reduction of 5–10dB of the required optical signal to noise ratio (OSNR) for an error-free transmission. Moreover, it significantly reduces the heterogeneity of the system performance for several distances, yielding a predictable behaviour, while at the same time permits the use of handy, inexpensive and integrated transmitters.
Reduced dispersion-induced harmonics levels are reported for analogue radio-over-fiber systems by using a linearized receiver incorporating a memoryless electronic circuit with square root ...(SQRT)-like transfer function, and performing amplitude modulation (AM) at the transmitter. A practical implementation demonstrates the effectiveness of the AM-SQRT approach in linearizing the optical transmission system with respect to the conventional intensity modulation and direct detection system
Este artículo trata sobre la política de construcciones escolares del franquismo a partir de los noticiarios del NO-DO como fuente de información. El análisis se centra en los noticiarios del NO-DO ...en los que el Ministro de Educación va a las escuelas de primaria. El artículo utiliza el NO-DO como fuente de información y los contrasta con la prensa escrita. El protagonismo del Ministro de Educación en el NO-DO es un reflejo de su política educativa, que respecto a las construcciones escolares estuvo marcada por numerosas deficiencias.
Salazar, Noel B. i Graburn, Nelson H. H. (eds.) (2014)Tourism imaginaries. Anthropological approachesOxford: Berghahn Books, 304 p.ISBN 978-1-78238-367-3
El turisme LGBT s’està consolidant com una important activitat dins del sector turístic. La ciutat de Barcelona no és aliena a aquesta tendència. No obstant això, la satisfacció obtinguda amb aquesta ...experiència depèn de diferents variables segons la motivació principal per realitzar aquest viatge. En aquest article s’analitzen aquests aspectes comparant els resultats de dues enquestes. La primera, a una mostra dels assistents al Festival Circuit, i la segona, a un grup de turistes LGBT aliens a aquest esdeveniment. D’aquesta manera s’ha confirmat que hi ha diferències significatives entre la valoració donada per aquests dos grups de turistes a les diferents variables que influeixen en el seu viatge. L’aspecte afectiu és el més valorat pels que realitzen el viatge sense el reclam d’un gran esdeveniment pensat per a aquest col·lectiu, encara que el component recreatiu té una gran influència entre els que assisteixen a un gran esdeveniment preparat per al col·lectiu LGBT.
A multi-layer next generation PON prototype has been built and tested, to show the feasibility of extended hybrid DWDM/TDM-XGPON FTTH networks with resilient optically-integrated ring-trees ...architecture, supporting broadband multimedia services. It constitutes a transparent common platform for the coexistence of multiple operators sharing the optical infrastructure of the central metro ring, passively combining the access and the metropolitan network sections. It features 32 wavelength connections at 10Gbps, up to 1000 users distributed in 16 independent resilient sub-PONs over 100km. This paper summarizes the network operation, demonstration and field trial results.
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