Dimming cellular networks

We propose a novel technique called dimming to improve the energy efficiency of cellular networks by reducing the capacity, services, and energy consumption of cells without turning off the cells. We define three basic methods to dim the network: coverage, frequency, and service dimming. We construct a multi-time period optimization problem to implement frequency dimming and extend it to implement both frequency and service dimming together. We illustrate the ability of dimming techniques to adapt the capacity and network services in proportion to the dynamic spatial and temporal load resulting in significant energy savings through numerical results for a sample network. ©2010 IEEE

Temporal Trends Of Energy Consumption And CO2 Emissions In Riyadh, Saudi Arabia

The consumption of material, energy, and water resources is inextricably linked to population growth with a unique impact on urban areas, especially in light of significant investments in infrastructure to support urban development. Urban metabolism is becoming popular as it provides a framework accounting the mass and energy flows through a city. An urban metabolism study was conducted to estimate the inputs and outputs of energy and pollutants from Riyadh, Saudi Arabia. The objective of this study was to determine the energy consumption of Riyadh using locally generated data from 1986, 1996, 2006, and 2012 and analysing the temporal trends of energy consumption and associated environmental impact. The socioeconomic and biophysical characteristics of Riyadh are well represented in its metabolism indicators. The high growth rate in population along with urban expansion has resulted in an increase in energy consumption. Riyadh has seen an increase in energy consumption at a rate of about 6% per annum. On a per capita basis, preliminary results show that the energy consumption increased by 31% from 1996 to 2012. Also, per capita CO2 emissions have increased by the same percentage. Results also show increasing mobile energy consumption from 20k TJ in 1986 to 157k TJ in 2012, which points to Riyadh’s inefficient urban form. The study findings highlight the importance for developing effective policies for improving the use of resources

Establishing domestic low energy consumption reference levels for Saudi Arabia and the wider Middle Eastern region

Saudi Arabia is renowned for its full reliance on fossil fuel energy and lack of an energy regulatory framework for its built environment. The paper focuses on the domestic sector and aims to: (a) establish levels of energy reduction, informed by leading standards (such as Passivhaus in Germany), that can be achieved taking into account the complex local socio-cultural context and environmental factors, and (b) propose a low energy reference definition with a view of encouraging energy retrofitting programs and enforcing domestic low carbon interventions. An energy simulation environment is employed to simulate and analyze energy consumption patterns of three proposed low carbon prototype houses that reflect current house typology and space layout in the country. The three proposed homes offer a reduction in energy consumption of up to 71.6%, compared with similar houses. Based on these findings, a domestic energy performance reference is proposed with energy consumption ranging between 77 kWh/m2 and 98 kWh/m2. Economic and environmental benefits are discussed as well as recommendations for enforcing low carbon design in the country and across the regio

Using scientific machine learning for experimental bifurcation analysis of dynamic systems

Augmenting mechanistic ordinary differential equation (ODE) models with machine-learnable structures is an novel approach to create highly accurate, low-dimensional models of engineering systems incorporating both expert knowledge and reality through measurement data. Our exploratory study focuses on training universal differential equation (UDE) models for physical nonlinear dynamical systems with limit cycles: an aerofoil undergoing flutter oscillations and an electrodynamic nonlinear oscillator. We consider examples where training data is generated by numerical simulations, whereas we also employ the proposed modelling concept to physical experiments allowing us to investigate problems with a wide range of complexity. To collect the training data, the method of control-based continuation is used as it captures not just the stable but also the unstable limit cycles of the observed system. This feature makes it possible to extract more information about the observed system than the standard, open-loop approach would allow. We use both neural networks and Gaussian processes as universal approximators alongside the mechanistic models to give a critical assessment of the accuracy and robustness of the UDE modelling approach. We also highlight the potential issues one may run into during the training procedure indicating the limits of the current modelling framework.Comment: 16 pages, 15 figure

Pathotypic diversity of Rhynchosporium secalis (Oudem) in Tunisia

Scald, caused by Rhynchosporium secalis (Oudem), is an important disease of barley in Tunisia particularly in northern, northwestern and central parts of the country where the climate is usually cold and wet during most of the barley growing season. Pathogenic variability of the barley scald pathogen in Tunisia was determined by testing the pathogenicity of 100 isolates from 5 different regions on 19 host differentials. Pathotypic diversity was high, with 93 R. secalis pathotypes identified on two differential sets (one comprising 9 and the other 10 barley lines) containing known resistance genes. A few pathotypes comprised 2% of the isolates; however, the majorities were represented by a single isolate. None of the differential lines was resistant to all isolates. The differential cultivar “Astrix” was the least compatible with the scald pathotypes followed by the differential cultivars “Atlas” and “Abyssinia”. Compatibility of the pathotypes on “Rihane” (69%) was close to that on “Osiris” (73%) and “La Mesita” (61%). None of the pathotypes was found in all the five regions of Tunisia surveyed. Some pathotypes were specific to a single region while others were found in several regions. The incidence of pathotypes varied considerably among regions, with region 3 (northwestern Tunisia) comprising the largest number of pathotypes. Virulent pathotypes were recovered in all regions but more pathotypic variability (44%) was observed in the semi-arid region 3. Differential cultivars allowed classification of R. secalis in four virulence groups. Canonical discriminant analysis showed no apparent association between virulence and geographical origin of the populations. Pathogenic variability in R. secalis in Tunisia was found not to be associated with geographical region, hence, the necessity for deployment of different resistance sources in major barley growing areas.Key words: Rhynchosporium secalis, barley, virulence groups, pathotypic variation

Experimental Study of Concrete Class Influence on Cracks Openings

The aim of this experimental work is to study reinforced concrete continuous beams cracking by considering different classes of concretes. As it is well known, the design of reinforced concrete structures considers three limit states (limit state of collapse, limit state of strain and limit state of cracking). The cracks in reinforced concrete structures are admitted in the phase II (cracked sections). Thus, the phenomenon of cracks can be treated as a normal state only when the cracks opening is limited to avoid a permanent risk of collapse and ensure durability for the civil engineering constructions. Tests on real scale reinforced concrete continuous beams were carried out under concentrated loads increasing from zero up to collapse. The influence of the concrete classes on crack opening has been investigated

Propuesta guía para una planeación y ejecución en proyectos de vivienda unifamiliar con enfoque Lean Construction

Trabajo de investigaciónEste trabajo contempla el desarrollo de una matriz enfocada en la metodología Lean Construction para la planeación y ejecución en proyectos de vivienda unifamiliar. Así mismo se evidencia un análisis de manera cuantitativa y cualitativamente en la adopción de la filosofía Lean Construction en procesos de la gestión de la planeación y ejecución de proyectos, que permite establecer un orden de actividades y sub actividades que componen las fases de un proyecto de vivienda unifamiliar en la relación del alcance exitoso en productividad y rendimiento.INTRODUCCIÓN 1. GENERALIDADES 2. METODOLOGÍAS EN EL MARCO DE LA PLANEACIÓN Y EJECUCIÓN DE PROYECTOS 3. LEAN CONSTRUCTION EN ACTIVIDADES DE CONSTRUCCIÓN 4. IMPLEMENTACIÓN DE LA MATRIZ EN CASO DE ESTUDIO 5. CONCLUSIONES 6. RECOMENDACIONES BIBLIOGRAFÍA ANEXOSPregradoIngeniero Civi