Predictive and distributed routing balancing (PR-DRB): high speed interconnection networks

Current parallel applications running on clusters require the use of an interconnection network to perform communications among all computing nodes available. Imbalance of communications can produce network congestion, reducing throughput and increasing latency, degrading the overall system performance. On the other hand, parallel applications running on these networks posses representative stages which allow their characterization, as well as repetitive behavior that can be identified on the basis of this characterization. This work presents the Predictive and Distributed Routing Balancing (PR-DRB), a new method developed to gradually control network congestion, based on paths expansion, traffic distribution and effective traffic load, in order to maintain low latency values. PR-DRB monitors messages latencies on intermediate routers, makes decisions about alternative paths and record communication pattern information encountered during congestion situation. Based on the concept of applications repetitiveness, best solution recorded are reapplied when saved communication pattern re-appears. Traffic congestion experiments were conducted in order to evaluate the performance of the method, and improvements were observed.

High-Speed Rail: lessons for policy makers from experiences abroad

In April 2009, the US government unveiled its blueprint for a national network of high-speed passenger rail (HSR) lines aimed at reducing traffic congestion, cutting national dependence on foreign oil and improving rural and urban environments. In implementing such a program, it is essential to identify the factors that might influence decision making and the eventual success of the HSR project, as well as foreseeing the obstacles that will have to be overcome.

Speed limit laws in America: economics, politics and geography

The regulation of speed limits in the US had been centralized at the federal level since 1974, until decisions were devolved to the states in 1995. However, the centralization debate has reemerged in recent years. Here, we conduct the first econometric analysis of the determinants of speed limit laws. By using economic, geographic and political variables, our results suggest that geography -which affects private mobility needs and preferences- is the main factor influencing speed limit laws. We also highlight the role played by political ideology, with Republican constituencies being associated with higher speed limits. Furthermore, we identify the presence of regional and time dependence effects. By contrast, poor road safety outcomes do not impede the enactment of high speed limits. Overall, we present the first evidence of the role played by geographical, ideological and regional characteristics, which provide us with a better understanding of the formulation of speed limit policies.

Comportamiento tribomecánico de sistemas de sustrato: recubrimiento duros

En aplicaciones como la conformación en frío, donde los metales duros recubiertos con películas de naturaleza cerámica son ampliamente empleados, la existencia de un contacto mecánico repetitivo induce tensiones Hertzianas y origina el fallo por fatiga. En este trabajo, se investigan diversos recubrimientos cerámicos depositados por deposición física desde fase vapor sobre calidades diferentes de metal duro y un acero rápido pulvimetalúrgico para evaluar sus respectivas respuesta al contacto y comportamiento a fatiga. El trabajo experimental incluye la caracterización de los sistemas mediante ensayos de rayado y nanoindentación y la evaluación de las curvas tensión-deformación de indentación esférica de los sustratos, tanto desnudos como recubiertos, poniendo especial atención en determinar las tensiones de contacto críticas asociadas a la deformación plástica y a la aparición de grietas circulares en la superficie recubierta. A este estudio, le siguen numerosos ensayos a fatiga a cargas inferiores a aquéllas identificadas como críticas bajo carga monotónica y para un número de ciclos comprendido entre 1.000 y 1.000.000 de ciclos. Los resultados experimentales indican que las películas cerámicas no parecen desempeñar un papel relevante en la aparición de la cedencia plástica, siendo la deformación plástica global controlada por la deformación del sustrato. No obstante, para tensiones elevadas de indentación durante el régimen plástico, existe la aparición de grietas circulares en los recubrimientos cerámicos. Además, la aparición de las mismas es sensible a la fatiga por contacto. Este análisis mecánico se complementa con una inspección detallada del daño generado en profundidad y superficie.

Políticas de encaminamiento tolerantes a fallos

El uso intensivo y prolongado de computadores de altas prestaciones para ejecutar aplicaciones computacionalmente intensivas, sumado al elevado número de elementos que los componen, incrementan drásticamente la probabilidad de ocurrencia de fallos durante su funcionamiento. El objetivo del trabajo es resolver el problema de tolerancia a fallos para redes de interconexión de altas prestaciones, partiendo del diseño de polí­ticas de encaminamiento tolerantes a fallos. Buscamos resolver una determinada cantidad de fallos de enlaces y nodos, considerando sus factores de impacto y probabilidad de aparición. Para ello aprovechamos la redundancia de caminos de comunicación existentes, partiendo desde enfoques de encaminamiento adaptativos capaces de cumplir con las cuatro fases de la tolerancia a fallos: detección del error, contención del daño, recuperación del error, y tratamiento del fallo y continuidad del servicio. La experimentación muestra una degradación de prestaciones menor al 5%. En el futuro, se tratará la pérdida de información en tránsito.

Scheduled service versus personal transportation: the role of distance

This paper analyzes both theoretically and empirically the relationship between distance and frequency of scheduled transportation services. We study the interaction between a monopoly firm providing high-speed scheduled service and personal trans- portation (i.e., car). Most interestingly, the carrier chooses to increase frequency of service on longer routes when competing with personal transportation because provid- ing a higher frequency (at extra cost) it can also charge higher fares that can boost its profits. However, when driving is not a relevant option, frequency of service de- creases for longer flights consistently with prior studies. An empirical application of our analysis to the European airline industry con?rms the predictions of our theoretical model.

Estudio de los efectos del movimiento en señales OFDM

El entorno aéreo es, a día de hoy, uno de los escenarios más complicados a la hora de establecer enlaces de comunicación fiables. Esto es debido, principalmente, a las altas velocidades a las que circulan los aviones, que propician una gran degradación del rendimiento des sistema si no se estima de forma continua el canal. Además el entorno aéreo es susceptible a sufrir muchos otros efectos que provocan la degradación de la señal, como la difracción, la reflexión, etc. Por este motivo en este proyecto se hace un estudio de dos escenarios típicos de vuelo: arrival (aterrizaje) y on route (vuelo en ruta). En el escenario on route los aviones circulan a más de el doble de velocidad que en el escenario arrival, de esta manera se podrá ver el efecto de sufrir un doppler mayor. Para realizar el estudio se utiliza un sistema multiportadora con solapamiento de subcanales, OFDM, y se toman inicialmente parámetros típicos de la tecnología WiMAX, que se variarán con el objetivo de mejorar el rendimiento del sistema.

Simulations of parasitic and intrinsic capacitances related to Multiple-Gate-Field-Effect Transistor architectures

Report for the scientific sojourn carried out at the Université Catholique de Louvain, Belgium, from March until June 2007. In the first part, the impact of important geometrical parameters such as source and drain thickness, fin spacing, spacer width, etc. on the parasitic fringing capacitance component of multiple-gate field-effect transistors (MuGFET) is deeply analyzed using finite element simulations. Several architectures such as single gate, FinFETs (double gate), triple-gate represented by Pi-gate MOSFETs are simulated and compared in terms of channel and fringing capacitances for the same occupied die area. Simulations highlight the great impact of diminishing the spacing between fins for MuGFETs and the trade-off between the reduction of parasitic source and drain resistances and the increase of fringing capacitances when Selective Epitaxial Growth (SEG) technology is introduced. The impact of these technological solutions on the transistor cut-off frequencies is also discussed. The second part deals with the study of the effect of the volume inversion (VI) on the capacitances of undoped Double-Gate (DG) MOSFETs. For that purpose, we present simulation results for the capacitances of undoped DG MOSFETs using an explicit and analytical compact model. It monstrates that the transition from volume inversion regime to dual gate behaviour is well simulated. The model shows an accurate dependence on the silicon layer thickness,consistent withtwo dimensional numerical simulations, for both thin and thick silicon films. Whereas the current drive and transconductance are enhanced in volume inversion regime, our results show thatintrinsic capacitances present higher values as well, which may limit the high speed (delay time) behaviour of DG MOSFETs under volume inversion regime.

Scheduled Service Versus Personal Transportation: The Role of Distance

This paper presents a theoretical and empirical analysis of the relationship be- tween frequency of scheduled transportation services and their substitutability with personal transportation (using distance as a proxy). We study the interaction between a monopoly firm providing a high-speed scheduled service and private transportation (i.e., car). Interestingly, the carrier chooses to increase the frequency of service on longer routes when competing with personal transportation because by providing higher frequency (at extra cost) it can also charge higher fares which can boost its profits. However, in line with the results of earlier studies, frequency decreases for longer flights when driving is not a viable option. An empirical application of our analysis to the European airline industry confirms the predictions of our theoretical model. Keywords: short-haul routes; long-haul routes; flight frequency; distance JEL Classification Numbers: L13; L2; L93

Deadlock avoidance with virtual channels

High Performance Computing is a rapidly evolving area of computer science which attends to solve complicated computational problems with the combination of computational nodes connected through high speed networks. This work concentrates on the networks problems that appear in such networks and specially focuses on the Deadlock problem that can decrease the efficiency of the communication or even destroy the balance and paralyze the network. Goal of this work is the Deadlock avoidance with the use of virtual channels, in the switches of the network where the problem appears. The deadlock avoidance assures that will not be loss of data inside network, having as result the increased latency of the served packets, due to the extra calculation that the switches have to make to apply the policy.

Desenvolupament d'eines d'alta ressolució per al cribatge (screening) de l'activitat de fàrmacs

Projecte de recerca elaborat a partir d’una estada a la Satandford University, EEUU, entre 2007 i 2009. Els darrers anys, hi ha hagut un avanç espectacular en la tecnologia aplicada a l’anàlisi del genoma i del proteoma (microarrays, PCR quantitativa real time, electroforesis dos dimensions, espectroscòpia de masses, etc.) permetent la resolució de mostres complexes i la detecció quantitativa de diferents gens i proteïnes en un sol experiment. A més a més, la seva importància radica en la capacitat d’identificar potencials dianes terapèutiques i possibles fàrmacs, així com la seva aplicació en el disseny i desenvolupament de noves eines de diagnòstic. L’aplicabilitat de les tècniques actuals, però, està limitada al nivell al que el teixit pot ser disseccionat. Si bé donen valuosa informació sobre expressió de gens i proteïnes implicades en una malaltia o en resposta a un fàrmac per exemple, en cap cas, s’obté una informació in situ ni es pot obtenir informació espacial o una resolució temporal, així com tampoc s’obté informació de sistemes in vivo. L’objectiu d’aquest projecte és desenvolupar i validar un nou microscopi, d’alta resolució, ultrasensible i de fàcil ús, que permeti tant la detecció de metabòlits, gens o proteïnes a la cèl•lula viva en temps real com l’estudi de la seva funció. Obtenint així una descripció detallada de les interaccions entre proteïnes/gens que es donen dins la cèl•lula. Aquest microscopi serà un instrument sensible, selectiu, ràpid, robust, automatitzat i de cost moderat que realitzarà processos de cribatge d’alt rendiment (High throughput screening) genètics, mèdics, químics i farmacèutics (per aplicacions diagnòstiques i de identificació i selecció de compostos actius) de manera més eficient. Per poder realitzar aquest objectius el microscopi farà ús de les més noves tecnologies: 1)la microscopia òptica i d’imatge, per millorar la visualització espaial i la sensibilitat de l’imatge; 2) la utilització de nous mètodes de detecció incloent els més moderns avanços en nanopartícules; 3) la creació de mètodes informàtics per adquirir, emmagatzemar i processar les imatges obtingudes.

Tren d’alta velocitat i desenvolupament local urbà. Aportacions a una nova base teòrica

Una de les finalitats principals del tren d’alta velocitat és la d’aportar desenvolupament local en aquelles ciutats i territoris on se’n construeixi una estació. Per aquesta raó, calen reflexions teòriques que ajudin els agents i les institucions a planificar correctament l’arribada de la nova gran infraestructura de transport, especialment en els aspectes relacionats amb la capacitat d’organització dels actors territorials. La teoria reticular pot ser una base teòrica útil per evitar concepcions deterministes de la relació entre infraestructura i territori, per explicar com es produeix el procés de desenvolupament local i per demostrar la importància dels agents territorials en aquest procés

Resource management research in Passive Optical Networks (PON)

Next Generation Access Networks (NGAN) are the new step forward to deliver broadband services and to facilitate the integration of different technologies. It is plausible to assume that, from a technological standpoint, the Future Internet will be composed of long-range high-speed optical networks; a number of wireless networks at the edge; and, in between, several access technologies, among which, the Passive Optical Networks (xPON) are very likely to succeed, due to their simplicity, low-cost, and increased bandwidth. Among the different PON technologies, the Ethernet-PON (EPON) is the most promising alternative to satisfy operator and user needs, due to its cost, flexibility and interoperability with other technologies. One of the most interesting challenges in such technologies relates to the scheduling and allocation of resources in the upstream (shared) channel. The aim of this research project is to study and evaluate current contributions and propose new efficient solutions to address the resource allocation issues in Next Generation EPON (NG-EPON). Key issues in this context are future end-user needs, integrated quality of service (QoS) support and optimized service provisioning for real time and elastic flows. This project will unveil research opportunities, issue recommendations and propose novel mechanisms associated with the convergence within heterogeneous access networks and will thus serve as a basis for long-term research projects in this direction. The project has served as a platform for the generation of new concepts and solutions that were published in national and international conferences, scientific journals and also in book chapter. We expect some more research publications in addition to the ones mentioned to be generated in a few months.