A simplified energy consumption model for fiber-based Next Generation Access Networks

ICTs account nowadays for 2% of total carbon emissions. However, in a time when strict measures to reduce energyconsumption in all the industrial and services sectors are required, the ICT sector faces an increase in services and bandwidth demand. The deployment of NextGenerationNetworks (NGN) will be the answer to this new demand and specifically, the NextGenerationAccessNetworks (NGANs) will provide higher bandwidth access to users. Several policy and cost analysis are being carried out to understand the risks and opportunities of new deployments, though the question of which is the role of energyconsumption in NGANs seems off the table. Thus, this paper proposes amodel to analyze the energyconsumption of the main fiber-based NGAN architectures, i.e. Fiber To The House (FTTH) in both Passive Optical Network (PON) and Point-to-Point (PtP) variations, and FTTx/VDSL. The aim of this analysis is to provide deeper insight on the impact of new deployments on the energyconsumption of the ICT sector and the effects of energyconsumption on the life-cycle cost of NGANs. The paper presents also an energyconsumption comparison of the presented architectures, particularized in the specific geographic and demographic distribution of users of Spain, but easily extendable to other countries.

A Simplified Energy Consumption Model for Fibre-Based Next Generation Access Networks

Presentación realizada en el PhD Seminar del ITS 2011 en Budapest. ICTs (Information and Communication Technologies) currently account for 2% of total carbon emissions. However, although modern standards require strict measures to reduce energy consumption across all industrial and services sectors, the ICT sector also faces an increase in services and bandwidth demand. The deployment of Next Generation Networks (NGN) will be the answer to this new demand; more specifically, Next Generation Access Networks (NGANs) will provide higher bandwidth access to users. Several policy and cost analyses are being carried out to understand the risks and opportunities of new deployments, but the question of what role energy consumption plays in NGANs seems off the table. Thus, this paper proposes a model to analyse the energy consumption of the main fibre-based NGAN architectures: Fibre To The House (FTTH), in both Passive Optical Network (PON) and Point-to-Point (PtP) variations, and FTTx/VDSL. The aim of this analysis is to provide deeper insight on the impact of new deployments on the energy consumption of the ICT sector and the effects of energy consumption on the life-cycle cost of NGANs. The paper also presents an energy consumption comparison of the presented architectures, particularised to the specific geographic and demographic distribution of users of Spain but easily extendable to other countries.

Control motion approach of a lower limb orthosis to reduce energy consumption

By analysing the dynamic principles of the human gait, an economic gait‐control analysis is performed, and passive elements are included to increase the energy efficiency in the motion control of active orthoses. Traditional orthoses use position patterns from the clinical gait analyses (CGAs) of healthy people, which are then de‐normalized and adjusted to each user. These orthoses maintain a very rigid gait, and their energy cosT is very high, reducing the autonomy of the user. First, to take advantage of the inherent dynamics of the legs, a state machine pattern with different gains in eachstate is applied to reduce the actuator energy consumption. Next, different passive elements, such as springs and brakes in the joints, are analysed to further reduce energy consumption. After an off‐line parameter optimization and a heuristic improvement with genetic algorithms, a reduction in energy consumption of 16.8% is obtained by applying a state machine control pattern, and a reduction of 18.9% is obtained by using passive elements. Finally, by combining both strategies, a more natural gait is obtained, and energy consumption is reduced by 24.6%compared with a pure CGA pattern.

Fuel poverty as a determinant in energy retrofitting actions

Fuel poverty can be defined as “the inability to afford adequate warmth in the home" and it is the result of the combination of three items: low household income, housing lack of energy efficiency and high energy bills. Although it affects a growing number of households within the European Union only some countries have an official definition for it. In 2013, the European Parliament claimed the Commission and Estate Members to develop different policies in order to fight household energy vulnerability. The importance of tackling fuel poverty is based on the critical consequences it has for human health living below certain temperatures. In Spain some advances have been made in this field but main existing studies remain at the statistical level and do not deepen the understanding of the problem from the perspective of dwelling indoor habitability conditions. What is more, this concept is yet to be officially defined. This paper presents the evaluation of fuel poverty in a building block of social housing located in the centre of Zaragoza and how this issue determined the strategies implemented in the energy retrofitting intervention project. At a first step, fuel poverty was appraised through the exploration of indoor thermal conditions. The adaptive thermal comfort (UNE-EN 15251:2008) method was used to establish the appropriate indoor temperatures and consequently to determine what can be called 'comfort gap'. Results were collated and verified with energy bills collection and a survey work that gathered data from neighbours. All this permitted pointing out those households more in need. Results from the social analysis combined with the evaluation of the building thermal performance determined the intervention. The renovation project was aimed at the implementation of passive strategies that improve households thermal comfort in order to alleviate households fuel poverty situation. This research is part of the project NewSolutions4OldHousing (LIFE10 ENV/ES/439) cofounded by the European Commission under the LIFE+ Programme.

Time domain passivity control for delayed teleoperation

La telepesencia combina diferentes modalidades sensoriales, incluyendo, entre otras, la visual y la del tacto, para producir una sensación de presencia remota en el operador. Un elemento clave en la implementación de sistemas de telepresencia para permitir una telemanipulación del entorno remoto es el retorno de fuerza. Durante una telemanipulación, la energía mecánica es transferida entre el operador humano y el entorno remoto. En general, la energía es una propiedad de los objetos físicos, fundamental en su mutual interacción. En esta interacción, la energía se puede transmitir entre los objetos, puede cambiar de forma pero no puede crearse ni destruirse. En esta tesis, se aplica este principio fundamental para derivar un nuevo método de control bilateral que permite el diseño de sistemas de teleoperación estables para cualquier arquitectura concebible. El razonamiento parte del hecho de que la energía mecánica insertada por el operador humano en el sistema debe transferirse hacia el entorno remoto y viceversa. Tal como se verá, el uso de la energía como variable de control permite un tratamiento más general del sistema que el control convencional basado en variables específicas del sistema. Mediante el concepto de Red de Potencia de Retardo Temporal (RPRT), el problema de definir los flujos de energía en un sistema de teleoperación es solucionado con independencia de la arquitectura de comunicación. Como se verá, los retardos temporales son la principal causa de generación de energía virtual. Este hecho se observa con retardos a partir de 1 milisegundo. Esta energía virtual es añadida al sistema de forma intrínseca y representa la causa principal de inestabilidad. Se demuestra que las RPRTs son transportadoras de la energía deseada intercambiada entre maestro y esclavo pero a la vez generadoras de energía virtual debido al retardo temporal. Una vez estas redes son identificadas, el método de Control de Pasividad en el Dominio Temporal para RPRTs se propone como mecanismo de control para asegurar la pasividad del sistema, y as__ la estabilidad. El método se basa en el simple hecho de que esta energía virtual debido al retardo debe transformarse en disipación. As__ el sistema se aproxima al sistema deseado, donde solo la energía insertada desde un extremo es transferida hacia el otro. El sistema resultante presenta dos cualidades: por un lado la estabilidad del sistema queda garantizada con independencia de la arquitectura del sistema y del canal de comunicación; por el otro, el rendimiento es maximizado en términos de fidelidad de transmisión energética. Los métodos propuestos se sustentan con sistemas experimentales con diferentes arquitecturas de control y retardos entre 2 y 900 ms. La tesis concluye con un experimento que incluye una comunicación espacial basada en el satélite geoestacionario ASTRA. ABSTRACT Telepresence combines different sensorial modalities, including vision and touch, to produce a feeling of being present in a remote location. The key element to successfully implement a telepresence system and thus to allow telemanipulation of a remote environment is force feedback. In a telemanipulation, mechanical energy must convey from the human operator to the manipulated object found in the remote environment. In general, energy is a property of all physical objects, fundamental to their mutual interactions in which the energy can be transferred among the objects and can change form but cannot be created or destroyed. In this thesis, we exploit this fundamental principle to derive a novel bilateral control mechanism that allows designing stable teleoperation systems with any conceivable communication architecture. The rationale starts from the fact that the mechanical energy injected by a human operator into the system must be conveyed to the remote environment and Vice Versa. As will be seen, setting energy as the control variable allows a more general treatment of the controlled system in contrast to the more conventional control of specific systems variables. Through the Time Delay Power Network (TDPN) concept, the issue of defining the energy flows involved in a teleoperation system is solved with independence of the communication architecture. In particular, communication time delays are found to be a source of virtual energy. This fact is observed with delays starting from 1 millisecond. Since this energy is added, the resulting teleoperation system can be non-passive and thus become unstable. The Time Delay Power Networks are found to be carriers of the desired exchanged energy but also generators of virtual energy due to the time delay. Once these networks are identified, the Time Domain Passivity Control approach for TDPNs is proposed as a control mechanism to ensure system passivity and therefore, system stability. The proposed method is based on the simple fact that this intrinsically added energy due to the communication must be transformed into dissipation. Then the system becomes closer to the ambitioned one, where only the energy injected from one end of the system is conveyed to the other one. The resulting system presents two benefits: On one hand, system stability is guaranteed through passivity independently from the chosen control architecture and communication channel; on the other, performance is maximized in terms of energy transfer faithfulness. The proposed methods are sustained with a set of experimental implementations using different control architectures and communication delays ranging from 2 to 900 milliseconds. An experiment that includes a communication Space link based on the geostationary satellite ASTRA concludes this thesis.

Assessment of expected damage on buildings subjected to Lorca earthquake through an energy-based seismic index method and nonlinear dynamic response analyses

The city of Lorca (Spain) was hit on May 11th, 2011, by two consecutive earth-quakes of magnitudes 4.6 and 5.2 Mw, causing casualties and important damage in buildings. Many of the damaged structures were reinforced concrete frames with wide beams. This study quantifies the expected level of damage on this structural type in the case of the Lorca earth-quake by means of a seismic index Iv that compares the energy input by the earthquake with the energy absorption/dissipation capacity of the structure. The prototype frames investigated represent structures designed in two time periods (1994–2002 and 2003–2008), in which the applicable codes were different. The influence of the masonry infill walls and the proneness of the frames to concentrate damage in a given story were further investigated through nonlinear dynamic response analyses. It is found that (1) the seismic index method predicts levels of damage that range from moderate/severe to complete collapse; this prediction is consistent with the observed damage; (2) the presence of masonry infill walls makes the structure very prone to damage concentration and reduces the overall seismic capacity of the building; and (3) a proper hierarchy of strength between beams and columns that guarantees the formation of a strong column-weak beam mechanism (as prescribed by seismic codes), as well as the adoption of counter-measures to avoid the negative interaction between non-structural infill walls and the main frame, would have reduced the level of damage from Iv=1 (collapse) to about Iv=0.5 (moderate/severe damage)

Reflectance properties analysis of mineral based mortars for renders: research of their energy performance

Passive performance of buildings is nowadays one of the key points, not only for reducing energy consumption of buildings, but also for decreasing “fuel poverty”. Among the constructive systems in buildings, façades are the ones having higher influence on thermal performance in urban spaces. Lime renders are specialized systems which can improve not only the durability of the support but also the thermal properties. According to previous researches, a modification of their radiative properties can reduce thermal fluxes between 24% and 89%. In this paper, the influences of the aggregate content in lime pastes, as well as the nature of the aggregates, colour and roughness, on the visible near and medium infrared reflectance are analyzed. Ten types of aerial lime mortars were prepared and two methods of reflectance determination were performed. Finally, the effect of the resulted reflectance on the constructive systems of façades was analyzed using pseudotime-dependent software, for which an annulation of the thermal fluxes or significant reduction of them can be observed, when modifying the aggregate nature.

Design and Simulation of Deep Nanometer SRAM Cells under Energy, Mismatch, and Radiation Constraints

La fiabilidad está pasando a ser el principal problema de los circuitos integrados según la tecnología desciende por debajo de los 22nm. Pequeñas imperfecciones en la fabricación de los dispositivos dan lugar ahora a importantes diferencias aleatorias en sus características eléctricas, que han de ser tenidas en cuenta durante la fase de diseño. Los nuevos procesos y materiales requeridos para la fabricación de dispositivos de dimensiones tan reducidas están dando lugar a diferentes efectos que resultan finalmente en un incremento del consumo estático, o una mayor vulnerabilidad frente a radiación. Las memorias SRAM son ya la parte más vulnerable de un sistema electrónico, no solo por representar más de la mitad del área de los SoCs y microprocesadores actuales, sino también porque las variaciones de proceso les afectan de forma crítica, donde el fallo de una única célula afecta a la memoria entera. Esta tesis aborda los diferentes retos que presenta el diseño de memorias SRAM en las tecnologías más pequeñas. En un escenario de aumento de la variabilidad, se consideran problemas como el consumo de energía, el diseño teniendo en cuenta efectos de la tecnología a bajo nivel o el endurecimiento frente a radiación. En primer lugar, dado el aumento de la variabilidad de los dispositivos pertenecientes a los nodos tecnológicos más pequeños, así como a la aparición de nuevas fuentes de variabilidad por la inclusión de nuevos dispositivos y la reducción de sus dimensiones, la precisión del modelado de dicha variabilidad es crucial. Se propone en la tesis extender el método de inyectores, que modela la variabilidad a nivel de circuito, abstrayendo sus causas físicas, añadiendo dos nuevas fuentes para modelar la pendiente sub-umbral y el DIBL, de creciente importancia en la tecnología FinFET. Los dos nuevos inyectores propuestos incrementan la exactitud de figuras de mérito a diferentes niveles de abstracción del diseño electrónico: a nivel de transistor, de puerta y de circuito. El error cuadrático medio al simular métricas de estabilidad y prestaciones de células SRAM se reduce un mínimo de 1,5 veces y hasta un máximo de 7,5 a la vez que la estimación de la probabilidad de fallo se mejora en varios ordenes de magnitud. El diseño para bajo consumo es una de las principales aplicaciones actuales dada la creciente importancia de los dispositivos móviles dependientes de baterías. Es igualmente necesario debido a las importantes densidades de potencia en los sistemas actuales, con el fin de reducir su disipación térmica y sus consecuencias en cuanto al envejecimiento. El método tradicional de reducir la tensión de alimentación para reducir el consumo es problemático en el caso de las memorias SRAM dado el creciente impacto de la variabilidad a bajas tensiones. Se propone el diseño de una célula que usa valores negativos en la bit-line para reducir los fallos de escritura según se reduce la tensión de alimentación principal. A pesar de usar una segunda fuente de alimentación para la tensión negativa en la bit-line, el diseño propuesto consigue reducir el consumo hasta en un 20 % comparado con una célula convencional. Una nueva métrica, el hold trip point se ha propuesto para prevenir nuevos tipos de fallo debidos al uso de tensiones negativas, así como un método alternativo para estimar la velocidad de lectura, reduciendo el número de simulaciones necesarias. Según continúa la reducción del tamaño de los dispositivos electrónicos, se incluyen nuevos mecanismos que permiten facilitar el proceso de fabricación, o alcanzar las prestaciones requeridas para cada nueva generación tecnológica. Se puede citar como ejemplo el estrés compresivo o extensivo aplicado a los fins en tecnologías FinFET, que altera la movilidad de los transistores fabricados a partir de dichos fins. Los efectos de estos mecanismos dependen mucho del layout, la posición de unos transistores afecta a los transistores colindantes y pudiendo ser el efecto diferente en diferentes tipos de transistores. Se propone el uso de una célula SRAM complementaria que utiliza dispositivos pMOS en los transistores de paso, así reduciendo la longitud de los fins de los transistores nMOS y alargando los de los pMOS, extendiéndolos a las células vecinas y hasta los límites de la matriz de células. Considerando los efectos del STI y estresores de SiGe, el diseño propuesto mejora los dos tipos de transistores, mejorando las prestaciones de la célula SRAM complementaria en más de un 10% para una misma probabilidad de fallo y un mismo consumo estático, sin que se requiera aumentar el área. Finalmente, la radiación ha sido un problema recurrente en la electrónica para aplicaciones espaciales, pero la reducción de las corrientes y tensiones de los dispositivos actuales los está volviendo vulnerables al ruido generado por radiación, incluso a nivel de suelo. Pese a que tecnologías como SOI o FinFET reducen la cantidad de energía colectada por el circuito durante el impacto de una partícula, las importantes variaciones de proceso en los nodos más pequeños va a afectar su inmunidad frente a la radiación. Se demuestra que los errores inducidos por radiación pueden aumentar hasta en un 40 % en el nodo de 7nm cuando se consideran las variaciones de proceso, comparado con el caso nominal. Este incremento es de una magnitud mayor que la mejora obtenida mediante el diseño de células de memoria específicamente endurecidas frente a radiación, sugiriendo que la reducción de la variabilidad representaría una mayor mejora. ABSTRACT Reliability is becoming the main concern on integrated circuit as the technology goes beyond 22nm. Small imperfections in the device manufacturing result now in important random differences of the devices at electrical level which must be dealt with during the design. New processes and materials, required to allow the fabrication of the extremely short devices, are making new effects appear resulting ultimately on increased static power consumption, or higher vulnerability to radiation SRAMs have become the most vulnerable part of electronic systems, not only they account for more than half of the chip area of nowadays SoCs and microprocessors, but they are critical as soon as different variation sources are regarded, with failures in a single cell making the whole memory fail. This thesis addresses the different challenges that SRAM design has in the smallest technologies. In a common scenario of increasing variability, issues like energy consumption, design aware of the technology and radiation hardening are considered. First, given the increasing magnitude of device variability in the smallest nodes, as well as new sources of variability appearing as a consequence of new devices and shortened lengths, an accurate modeling of the variability is crucial. We propose to extend the injectors method that models variability at circuit level, abstracting its physical sources, to better model sub-threshold slope and drain induced barrier lowering that are gaining importance in FinFET technology. The two new proposed injectors bring an increased accuracy of figures of merit at different abstraction levels of electronic design, at transistor, gate and circuit levels. The mean square error estimating performance and stability metrics of SRAM cells is reduced by at least 1.5 and up to 7.5 while the yield estimation is improved by orders of magnitude. Low power design is a major constraint given the high-growing market of mobile devices that run on battery. It is also relevant because of the increased power densities of nowadays systems, in order to reduce the thermal dissipation and its impact on aging. The traditional approach of reducing the voltage to lower the energy consumption if challenging in the case of SRAMs given the increased impact of process variations at low voltage supplies. We propose a cell design that makes use of negative bit-line write-assist to overcome write failures as the main supply voltage is lowered. Despite using a second power source for the negative bit-line, the design achieves an energy reduction up to 20% compared to a conventional cell. A new metric, the hold trip point has been introduced to deal with new sources of failures to cells using a negative bit-line voltage, as well as an alternative method to estimate cell speed, requiring less simulations. With the continuous reduction of device sizes, new mechanisms need to be included to ease the fabrication process and to meet the performance targets of the successive nodes. As example we can consider the compressive or tensile strains included in FinFET technology, that alter the mobility of the transistors made out of the concerned fins. The effects of these mechanisms are very dependent on the layout, with transistor being affected by their neighbors, and different types of transistors being affected in a different way. We propose to use complementary SRAM cells with pMOS pass-gates in order to reduce the fin length of nMOS devices and achieve long uncut fins for the pMOS devices when the cell is included in its corresponding array. Once Shallow Trench isolation and SiGe stressors are considered the proposed design improves both kinds of transistor, boosting the performance of complementary SRAM cells by more than 10% for a same failure probability and static power consumption, with no area overhead. While radiation has been a traditional concern in space electronics, the small currents and voltages used in the latest nodes are making them more vulnerable to radiation-induced transient noise, even at ground level. Even if SOI or FinFET technologies reduce the amount of energy transferred from the striking particle to the circuit, the important process variation that the smallest nodes will present will affect their radiation hardening capabilities. We demonstrate that process variations can increase the radiation-induced error rate by up to 40% in the 7nm node compared to the nominal case. This increase is higher than the improvement achieved by radiation-hardened cells suggesting that the reduction of process variations would bring a higher improvement.

Energy rehabilitation of social housing for rent, as demonstrator in the LIFE 'New4Old' Project

The main goal of the cofounded by the European Commission LIFE Project, New4Old (LIFE10 ENV/ES/439), is to define the most appropriate method and the best available practice in social housing rehabilitation with energy and environmental sustainability criteria, as well as to apply innovative technologies in the fight against climate change through an efficient use of resources and energy. The institutions involved in the Project are the Technological Centre AITEMIN, Madrid Polytechnic University (UPM), Portugal Technological Centre for Ceramics and Glass (CTCV) and the Zaragoza City Housing Society (SMZV). The demonstrator project consists in the energy rehabilitation of a rental social housing building located in Zaragoza?s historic quarter, according to the conclusions and strategies developed for the LIFE project. In actions taken in households of this nature passive design strategies are essential due to the limited income of owners, who often cannot afford energy bills. Therefore, the proposed actions will help improve the building?s passive performance and reach a higher thermal comfort, without increasing the economic cost linked to energy consumption.

Experimental study of the thermal-energy performance of an insulated vegetal facade under summer conditions in a continental mediterranean climate

The use of vegetal systems in facades affects the reduction of the buildings' energy demand, the attenuation of the urban heat island (UHI) and the filtration of pollutants present in the air. Even so, up to now the knowledge about the effect of this type of systems on the thermal performance of insulated facades is limited. This article presents the results of an experimental study carried out in a vegetal facade located in a continental Mediterranean climate zone. The objective is to study the effect of a vegetal finishing, formed by plants and substrate, on the thermal-energy performance of an insulated facade under summer conditions. To this effect, the thermal data obtained from two full-scale experimental mock-ups of the same dimensions and composition of the enclosure and only different in the south facade's enclosure where one incorporates a vegetation layer are compared and analysed. The results show that, in spite of the high thermal resistance of the enclosure, the effect of the vegetation is very positive, particularly in the warmer hours of the day. Therefore, vegetal facades can be used as a passive cooling strategy, reducing the consumption of energy for refrigeration and improving the comfort conditions of the users. (C) 2014 Elsevier Ltd. All rights reserved.

Sustainability assessment of energy saving measures: A multi-criteria approach for residential buildings retrofitting—A case study of the Spanish housing stock

The building sector is well known to be one of the key energy consumers worldwide. The renovation of existing buildings provides excellent opportunities for an effective reduction of energy consumption and greenhouse gas emissions but it is essential to identify the optimal strategies. In this paper a multi-criteria methodology is proposed for the comparative analysis of retrofitting solutions. Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) are combined by expressing environmental impacts in monetary values. A Pareto optimization is used to select the preferred strategies. The methodology is exemplified by a case study: the renovation of a representative housing block from the 1960s located in Madrid. Eight scenarios have been proposed, from the Business as Usual scenario (BAU), through Spanish Building Regulation requirements (for new buildings) up to the Passive House standard. Results show how current renovation strategies that are being applied in Madrid are far from being optimal solutions. The required additional investment, which is needed to obtain an overall performance improvement of the envelope compared with the common practice to date, is relatively low (8%) considering the obtained life cycle environmental and financial savings (43% and 45%, respectively).

Energy efficiency evaluation of zero energy houses

Given the global energy and environmental situation, the European Union has been issuing directives with increasingly demanding requirements in term of the energy efficiency in buildings. The international competition of sustainable houses, Solar Decathlon Europe (SDE), is aligned with these European objectives. SDE houses are low energy solar buildings that must reach the near to zero energy houses’ goal. In the 2012 edition, in order to emphasize its significance, the Energy Efficiency Contest was added. SDE houses’ interior comfort, functioning and energy performance is monitored. The monitoring data can give an idea about the efficiency of the houses. However, a jury comprised by international experts is responsible for carrying out the houses energy efficiency evaluation. Passive strategies and houses services are analyzed. Additionally, the jury's assessment has been compared with the behavior of the houses during the monitoring period. Comparative studies make emphasis on the energy aspects, houses functioning and their interior comfort. Conclusions include thoughts related with the evaluation process, the results of the comparative studies and suggestions for the next competitions.

A resistance emulation approach to optimize the wave energy harvesting for a direct drive point absorber

In general, a major challenge for the exploitation of renewable energies is to improve their efficiency. In electricity generation from the energy of ocean waves, not unlike other technologies, the converter must be optimized to make the energy harvesting economically feasible. This paper proposes a passive tuning control strategy of a point absorber in which the power captured is maximized by controlling the electromagnetic force of the generator with a resistance emulation approach. The proposed strategy consists of mapping the optimal values for regular waves and applying them to irregular waves. This strategy is tested in a wave energy converter in which the generator is connected to a boost rectifier converter whose controller is designed to emulate a resistance. The power electronics system implemented is validated by comparing its performance with the case in which the generator is directly connected to a resistive load. The simulation results show the effectiveness of the proposed strategy as the maximum captured power is concentrated around the optimal values previously calculated and with the same behavior for both excitations.