Ultrafast wavelength jumping and wavelength adjustment with low current using monolithically integrated FML for long-reach UDWDM-PON

Ultrafast wavelength jumping at optical network units (ONUs) for an access network with frequency modulated lasers (FMLs) is demonstrated. This FML consists of an intracavity tunable phase section and filtering gain section. It provides a total of 4.2 nm tuning range with fast wavelength jumping (2.2 nm in 1 µs) and fast adjustment (1.3 nm in 1.8 ns), providing a candidate for the fast tuning ONU for coherent ultradense wavelength-division multiplexing passive optical networks (WDM-PONs).Peer ReviewedPostprint (author's final draft

Dispersion-shifted fiber polarization scrambler based on faraday effect

Demonstration of an all-fiber polarization scrambler based on the Faraday effect is carried out. The device has been constructed using dispersion-shifted fiber that has a major tolerance to bends than standard single-mode fiber. Results about the fiber Verdet constant when 1550-nm light is launched are presented. The performance of the constructed device is also shown. Main features are insertion losses as low as 0.4 dB and scrambling frequency up to 20 kHz. Although here we emphasize its application to low-frequency heterodyne detection, the scrambler is applicable to other systems that are polarization dependent. In particular, it would be useful to overcome problems originated by polarization dependent gain in erbium-doped fiber amplified systems.Peer ReviewedPostprint (published version

Videojoc retro

El treball consisteix en l’estudi, el disseny, i la creació d’un prototipat d’una consola de videojocs de 8 bits i la programació dels videojocs integrats en la consola, en concret tres de diferents. Els jocs que incorpora la consola són retro, és a dir, entre els anys setanta i vuitanta ja existien com és el cas de l’Snake, un dels tres jocs programats. En el present document es recull en tots els coneixements necessaris per ajudar a arribar al lector a una millor comprensió del treball realitzat. S’explica el funcionament del microcontrolador i la seva connexió amb els elements externs necessaris per a una consola;com la pantalla, l’altaveu i els diversos polsadors. De la mateixa manera que s’explica el hardware de la consola, també es comenta la seva programació, en aquest cas, mitjançant el llenguatge C amb l’entorn de desenvolupament adequat pel microcontrolador. D’aquesta manera es donen tots els conceptes bàsics per poder comprendre tot el funcionament de la consola, des de l’apartat de hardware fins al software

Put three and three together: Triangle-driven community detection

Community detection has arisen as one of the most relevant topics in the field of graph data mining due to its applications in many fields such as biology, social networks, or network traffic analysis. Although the existing metrics used to quantify the quality of a community work well in general, under some circumstances, they fail at correctly capturing such notion. The main reason is that these metrics consider the internal community edges as a set, but ignore how these actually connect the vertices of the community. We propose the Weighted Community Clustering (WCC), which is a new community metric that takes the triangle instead of the edge as the minimal structural motif indicating the presence of a strong relation in a graph. We theoretically analyse WCC in depth and formally prove, by means of a set of properties, that the maximization of WCC guarantees communities with cohesion and structure. In addition, we propose Scalable Community Detection (SCD), a community detection algorithm based on WCC, which is designed to be fast and scalable on SMP machines, showing experimentally that WCC correctly captures the concept of community in social networks using real datasets. Finally, using ground-truth data, we show that SCD provides better quality than the best disjoint community detection algorithms of the state of the art while performing faster.Peer ReviewedPostprint (author's final draft

Ressenyes

Obra ressenyada: Enric JULIANA, Modesta España: Paisaje después de la austeridad. Barcelona: RBA Libros. Serie Política y Sociedad, 2012