Telecommunications Network Planning and Maintenance

Telecommunications network operators are on a constant challenge to provide new services which require ubiquitous broadband access. In an attempt to do so, they are faced with many problems such as the network coverage or providing the guaranteed Quality of Service (QoS). Network planning is a multi-objective optimization problem which involves clustering the area of interest by minimizing a cost function which includes relevant parameters, such as installation cost, distance between user and base station, supported traffic, quality of received signal, etc. On the other hand, service assurance deals with the disorders that occur in hardware or software of the managed network. This paper presents a large number of multicriteria techniques that have been developed to deal with different kinds of problems regarding network planning and service assurance. The state of the art presented will help the reader to develop a broader understanding of the problems in the domain

Liquid water at crater Gale, Mars

Suspicion that Mars could have transient liquid water on its surface through deliquescence of salts to form aqueous solutions or brines is an old proposal whose inquiry was boosted by Phoenix Lander observations. It provided some images of what were claimed to be brines, the presence of which at its landing site was compatible with the atmospheric parameters and the composition of the soil observed. On the other hand, the so called Recurrent Slope Lineae (RSL) often imaged by orbiters, were considered as another clue pointing to the occurrence of the phenomenon, since it was thought that they might be caused by it. Now, Curiosity rover has performed the first in-situ multi-instrumental study on Mars’ surface, having collected the most comprehensive environmental data set ever taken by means of their instruments Rover Environmental Monitoring Station (REMS), Dynamic Albedo of Neutrons (DAN), and Sample Analysis at Mars (SAM). REMS is providing continuous and accurate measurements of the relative humidity and surface and air temperatures among other parameters, and DAN and SAM provide the water content of the regolith and the atmosphere respectively. Analysis of these data has allowed to establish the existence of a present day active water cycle between the atmosphere and the regolith, that changes according to daily and seasonal cycles, and that is mediated by the presence of brines during certain periods of each and every day. Importantly, the study shows that the conditions for the occurrence of deliquescence are favourable even at equatorial latitudes where, at first, it was thought they were not due to the temperature and relative humidity conditions. This study provides new keys for the understanding of martian environment, and opens interesting lines of research and studies for future missions which may even have a bearing on extant microbial life.Godkänd; 2015; 20150702 (javmar

Planetary exploration; Mars on the scope

This article summarizes a practical case of introduction to research and planetary exploration through the analysis of data from the Rover Environmental Monitoring Station (REMS), one of the ten scientific instruments on board the Curiosity rover of the Mars Science Laboratory (MSL), currently operating at the impact crater Gale, on Mars. It is the main aim of this work to show how the data that are publicly available at the Planetary Data System (PDS) can be used to introduce undergraduate students and the general public into the subject of surface exploration and the environment of Mars. In particular, the goal of this practice was to investigate and quantify the heat flux between the rover spacecraft and the Martian surface, the role of the atmosphere in this interaction, and its dependence with seasons, as well as to estimate the thermal contamination of the Martian ground produced by the rover. The ground temperature sensor (GTS) of the REMS instrument has measured in-situ, for the first time ever, the diurnal and seasonal variation of the temperature of the surface on Mars along the rover traverse. This novel study shows that the rover radiative heat flux varies between 10 and 22 W/m2 during the Martian year, which is more than 10% of the solar daily averaged insolation at the top of the atmosphere. In addition, it is shown that the radiative heat flux from the rover to the ground varies with the atmospheric dust load, being the mean annual amplitude of the diurnal variation of the surface temperature of 76 K, as a result of solar heating during the day and infrared cooling during the night. As a remarkable and unexpected outcome, it has been established that the thermal contamination produced by the rover alone induces, on average, a systematic shift of 7.5 K, which is indeed about 10% of the one produced by solar heating. This result may have implications for the design and operation of future surface exploration probes such as InSight.Godkänd; 2015; 20150702 (javmar