Telecommunications Networks

This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals. Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing

Transferências de dados em massa sensíveis ao consumo energético em Redes Ópticas Elásticas

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2019.O tráfego entre Data Centers (Centro de dados – CD) na Internet tem crescido de maneira relevante nas duas últimas décadas e a tendência é que essa demanda aumente ainda mais principalmente nas redes de núcleo em função de serviços que geram grande volume de tráfego tais como aplicações de vídeo, computação em nuvem, dentre outros. Para tal, estudos têm sido feitos para que haja um maior aproveitamento da largura de banda nas redes ópticas. Muitos destes estudos estão pautados no advento das Redes Ópticas Elásticas (Elastic Optical Networks – EONs); as quais possibilitam um maior aproveitamento espectral do meio de transmissão óptico. Diversas características das EONs precisam ser aperfeiçoadas, dentre elas a eficiência energética, haja vista que o consumo sustentável é necessário. Em meio a estas temáticas há, também, as Transferências de Dados em Massa (Bulk Data Transfers – BDT), operação frequente entre CDs com grandes volumes de dados, tolerantes a atraso e com alto consumo de energia. Há, então, uma necessidade de estudar e propor soluções para transações de grande fluxo de dados entre CDs cientes de eficiência energética considerando o paradigma das Redes Ópticas Elásticas. Portanto, este trabalho visa propor soluções para o transporte de BDTs entre CDs com eficiência energética em uma EON.The inter Data Centers (IDC) traffic on the Internet has grown considerably over the last two decades, and the trend is that this demand will increase even more especially in core networks because of services that generate large volumes of traffic such as video applications, cloud computing, among others. To this new class of applications, studies have been done to better explore the available bandwidth in optical networks. Many of these studies are considering the advent of Elastic Optical Networks (EONs); which make possible a better spectral utilization of the optical transmission medium. Several characteristics of EONs need to be improved, including energy efficiency; given that sustainable consumption is necessary. Moreover there are Bulk Data Transfers (BDT), which are frequent IDC operations with large volumes of data, delay tolerance and with high energy consumption. There is, therefore, a need to study and propose feasible solutions for enabling energy-aware large data flow IDC transactions on top of an Elastic Optical Network infrastructure. Therefore, this work aims to propose solutions for the transport of IDC BDTs with energy-efficient in an EON

Soil-Water Conservation, Erosion, and Landslide

The predicted climate change is likely to cause extreme storm events and, subsequently, catastrophic disasters, including soil erosion, debris and landslide formation, loss of life, etc. In the decade from 1976, natural disasters affected less than a billion lives. These numbers have surged in the last decade alone. It is said that natural disasters have affected over 3 billion lives, killed on average 750,000 people, and cost more than 600 billion US dollars. Of these numbers, a greater proportion are due to sediment-related disasters, and these numbers are an indication of the amount of work still to be done in the field of soil erosion, conservation, and landslides. Scientists, engineers, and planners are all under immense pressure to develop and improve existing scientific tools to model erosion and landslides and, in the process, better conserve the soil. Therefore, the purpose of this Special Issue is to improve our knowledge on the processes and mechanics of soil erosion and landslides. In turn, these will be crucial in developing the right tools and models for soil and water conservation, disaster mitigation, and early warning systems

Observational and Theoretical Investigation of Cylindrical Line Source Blast Theory Using Meteors

During their passage through the atmosphere meteoroids produce a hypersonic shock which may be recorded at the ground in the form of infrasound. The first objective of this project was to use global infrasound measurements to estimate the influx of large (meter/decameter) objects to Earth and investigate which parameters of their ablation and disruption can be determined using infrasound records. A second objective was to evaluate and extend existing cylindrical line source blast theory for meteoroids by combining new observations with earlier analytical models, and validate these against centimetre-sized optical meteor observations. The annual terrestrial influx of large meteoroids (kinetic energies above a threshold E) was found to be N=4.5E–0.6 where E is expressed in kilotons of TNT equivalent. This indicates that estimates of the influx derived from telescopic surveys of small asteroids near Earth are too low. Infrasound records from an event over Indonesia in 2009 were used to develop a technique to estimate the altitude of meteoroid terminal bursts and their energies. The burst altitude in this case was determined to be near 20 kilometers and the energy between 8 – 67 kilotons of TNT equivalent. Using a network of optical cameras and an Infrasound Array in southern Ontario, Canada, 71 centimetre-sized meteoroids were optically detected and associated with infrasonic signals recorded at the ground. The shock source height and its uncertainty along the meteor trail from raytracing was determined including wind effects due to gravity waves perturbations, which were found to be significant for such short range (km) infrasound propagation. Approximately 75% of signals were attributed to cylindrical line source geometry, while ray deviation angles greater than 117° were associated with spherical shocks. The ReVelle (1974) meteor infrasound model was found to be accurate when using infrasound period measurements, but systematically under-predicted blast radii when amplitude is used. The latter can be better modelled assuming the wave distortion distance is “\u3c6%, as opposed to the 10% adopted by ReVelle. Infrasonic masses found from ReVelle’s theory deviate from photometric estimates largely due to meteoroid fragmentation

Annual Meeting of the Lunar Exploration Analysis Group : October 20 - 22, 2015, Columbia, Maryland, USRA Headquarters

The meeting goals are three-fold: 1. Integrate the perspectives and interests of the different stakeholders (science, engineering, government, and private sector) to explore common goals of lunar exploration. This meeting is focused around the identification, evaluation, extraction, and use of lunar resources. 2. Use the results of recent and ongoing missions to examine the dynamic nature of the Moon and how this could influence future science and exploration missions. 3. Provide a forum for community updates and input into the issues that affect lunar science and exploration.NASA Lunar Exploration Analysis Group (LEAG), Universities Space Research Association (USRA), Lunar and Planetary Institute (LPI), NASA Solar System Exploration Research Virtual Institute (SSERVI), National Aeronautics and Space Administration (NASA)Science Organizing Committee, James Carpenter, ESA-ESTE

Feature Papers of Drones - Volume II

[EN] The present book is divided into two volumes (Volume I: articles 1–23, and Volume II: articles 24–54) which compile the articles and communications submitted to the Topical Collection ”Feature Papers of Drones” during the years 2020 to 2022 describing novel or new cutting-edge designs, developments, and/or applications of unmanned vehicles (drones). Articles 24–41 are focused on drone applications, but emphasize two types: firstly, those related to agriculture and forestry (articles 24–35) where the number of applications of drones dominates all other possible applications. These articles review the latest research and future directions for precision agriculture, vegetation monitoring, change monitoring, forestry management, and forest fires. Secondly, articles 36–41 addresses the water and marine application of drones for ecological and conservation-related applications with emphasis on the monitoring of water resources and habitat monitoring. Finally, articles 42–54 looks at just a few of the huge variety of potential applications of civil drones from different points of view, including the following: the social acceptance of drone operations in urban areas or their influential factors; 3D reconstruction applications; sensor technologies to either improve the performance of existing applications or to open up new working areas; and machine and deep learning development

Staring down the lion: Uncertainty avoidance and operational risk culture in a tourism organisation

The academic literature is not clear about how uncertainty influences operational risk decision-making. This study, therefore, investigated operational risk-based decision-making in the face of uncertainty in a large African safari tourism organisation by exploring individual and perceived team member approaches to uncertainty. Convenience sampling was used to identify 15 managers across three African countries in three domains of work: safari camp; regional office; and head office. Semi-structured interviews were conducted in which vignettes were incorporated, to which participants responded with their own reactions and decisions to the situations described, as well as with ways they thought other managers would react to these specific operational contexts. The data were transcribed and qualitatively analysed through thematic coding processes. The findings indicated that approaches to uncertainty were influenced by factors including situational context, the availability and communication of information, the level of operational experience, and participants’ roles. Contextual factors alongside diverse individual emotional and cognitive influences were shown to require prudent consideration by safari tourism operators in understanding employee behavioural reactions to uncertain situations. A preliminary model drawn from the findings suggests that, in practice, decision-making in the face of uncertainty is more complex than existing theoretical studies propose. Specifically, the diverse responses anticipated by staff in response to the vignettes could guide safari tourism management towards better handling of risk under uncertainty in remote locations