Results for Channel Error Profiles for DECT

This letter presents the main statistical characterization of the underlying error process obtained in the case of the Digital European Cordless Telecommunications (DECT) radio system. By simulation of the transmission link, error sequences are generated for different channel parameters. Relevant statistics are then computed for the purpose of efficient channel coding design and evaluation

Bone mechanical stimulation with piezoelectric materials

This chapter summarized explores in vivo use of a piezoelectric polymer for bone mechanical stimulatio

Piezoelectric actuators for bone mechanical stimulation: exploring the concept.

Arthroplasty is liable to cause intense changes on strain levels and distribution in the boné surrounding the implant, namely stress shielding. Several solutions have been proposed for this, namely design variations and development of controlled-stiffness implants. A new approach to this problem, with potential application to other orthopaedic problems and other medical fields, would be the development of smart implants integrating systems for bone mechanical stimulation. Ideally, the implant should presente sensing capability and the ability to maintain physiological levels of strain at the implant interface. Piezoelectric materials’ huge potential as a mean to produce direct mechanical stimulation lies on the possibility of producing stimuli at a high range of frequencies and in multiple combinations. The present in vitro and preliminary in vivo studies were a first step towards the validation of the concept

From mobile phone data to the spatial structure of cities

Pervasive infrastructures, such as cell phone networks, enable to capture large amounts of human behavioral data but also provide information about the structure of cities and their dynamical properties. In this article, we focus on these last aspects by studying phone data recorded during 55 days in 31 Spanish metropolitan areas. We first define an urban dilatation index which measures how the average distance between individuals evolves during the day, allowing us to highlight different types of city structure. We then focus on hotspots, the most crowded places in the city. We propose a parameter free method to detect them and to test the robustness of our results. The number of these hotspots scales sublinearly with the population size, a result in agreement with previous theoretical arguments and measures on employment datasets. We study the lifetime of these hotspots and show in particular that the hierarchy of permanent ones, which constitute the "heart" of the city, is very stable whatever the size of the city. The spatial structure of these hotspots is also of interest and allows us to distinguish different categories of cities, from monocentric and "segregated" where the spatial distribution is very dependent on land use, to polycentric where the spatial mixing between land uses is much more important. These results point towards the possibility of a new, quantitative classification of cities using high resolution spatio-temporal data.Comment: 14 pages, 15 figure

Uncovering the spatial structure of mobility networks

The extraction of a clear and simple footprint of the structure of large, weighted and directed networks is a general problem that has many applications. An important example is given by origin-destination matrices which contain the complete information on commuting flows, but are difficult to analyze and compare. We propose here a versatile method which extracts a coarse-grained signature of mobility networks, under the form of a $2\times 2$ matrix that separates the flows into four categories. We apply this method to origin-destination matrices extracted from mobile phone data recorded in thirty-one Spanish cities. We show that these cities essentially differ by their proportion of two types of flows: integrated (between residential and employment hotspots) and random flows, whose importance increases with city size. Finally the method allows to determine categories of networks, and in the mobility case to classify cities according to their commuting structure.Comment: 10 pages, 5 figures +Supplementary informatio

Development of New-Concept Clean Technologies to Extract Metals from Primary and Secondary Sources

Development of new-concept hydrometallurical technologies promoted by Tecnicas Reunidas is providing efficient and clean means for metals extraction from diverse primary & secondary sources, such as conventional or low-grade concentrates and ores, lead-acid batteries, domestic batteries, effluents from electronic industry, etc. Rele-vant characteristics of the recently developed processes regarding extraction of zinc, lead, silver, nickel and copper metals are the following: environmentally friendly, value added products and by-products, flexibility to a great variety of feed materials, adapted to local market requirements, easy to be combined with existing plants available for small and large capacities and on-site installation close to the metal sources

Servitization strategies from customers’ perspective: the moderating role of co-creation

© 2018, Emerald Publishing Limited. Purpose: This paper aims to investigate the moderating role of co-creation in the implementation of servitization strategies in the pharmaceutical industry in a business-to-business (B-to-B) context. More specifically, this investigation explores the impact of different levels of services (base, intermediate and advanced) on servitization and on performance by using co-creation as a moderating factor. Design/methodology/approach: A research framework was developed and empirically tested in the pharmaceutical sector. Data collection was conducted through the online distribution of questionnaires. The final sample included 219 pharmacy stores, and the data were analysed using structural equation modelling. Findings: Main findings suggest that when the level of co-creation of the design of services is high, there are significant effects of servitization on firm performance. The moderating effect of co-creation is illustrated in regard to intermediate and advanced services, but results referring to the impact of intermediate services on servitization appear non-significant with a low degree of co-creation. No significant effects could be found for the impact of base services on performance and servitization for both high and low degrees of co-creation. Findings show an impact of advanced services on performance through the mediating effect of servitization when the degree of co-creation is high. Originality/value: Most research concerning servitization has been done from the perspective of manufacturers and service providers. This study adds value to the literature because it was designed from a customer’s perspective. Moreover, it contributes towards the conceptualization of the servitization research strategy and business models in a B2B context. This is accomplished through the investigation of the moderating effect of co-creation on the impact of the different levels of services on servitization and on performance

Behavior-Profile Clustering for False Alert Reduction in Anomaly Detection Sensors

Anomaly detection (AD) sensors compute behavior profiles to recognize malicious or anomalous activities. The behavior of a host is checked continuously by the AD sensor and an alert is raised when the behavior deviates from its behavior profile. Unfortunately, the majority of AD sensors suffer from high volumes of false alerts either maliciously crafted by the host or originating from insufficient training of the sensor. We present a cluster-based AD sensor that relies on clusters of behavior profiles to identify anomalous behavior. The behavior of a host raises an alert only when a group of host profiles with similar behavior (cluster of behavior profiles) detect the anomaly, rather than just relying on the host's own behavior profile to raise the alert (single-profile AD sensor). A cluster-based AD sensor significantly decreases the volume of false alerts by providing a more robust model of normal behavior based on clusters of behavior profiles. Additionally, we introduce an architecture designed for the deployment of cluster-based AD sensors. The behavior profile of each network host is computed by its closest switch that is also responsible for performing the anomaly detection for each of the hosts in its subnet. By placing the AD sensors at the switch, we eliminate the possibility of hosts crafting malicious alerts. Our experimental results based on wireless behavior profiles from users in the CRAWDAD dataset show that the volume of false alerts generated by cluster-based AD sensors is reduced by at least 50% compared to single-profile AD sensors

Experiência no curso de estudantes de 1º ano – um estudo no âmbito das tutorias de acompanhamento na Universidade de Évora

O presente estudo pretende conhecer a experiência no curso de estudantes de 1º ano que ingressaram na Universidade de Évora no final do 1º semestre. Estudos realizados sobre a percepção dos estudantes relativa ao contexto de aprendizagem no ensino superior indicam forte relação com as abordagens à aprendizagem e apresentam forte relevância para a compreensão da forma como os estudantes acedem ao conhecimento e para a definição de processos de aprendizagem de elevada qualidade (Entwistle, 2009; Chaleta & Entwistle, 2011). Os dados foram obtidos através da aplicação do CEQP (Ramsden, 2005; 2006; Chaleta et al, 2012) com 565 estudantes de diferentes cursos e áreas científicas. Os resultados indicaram que a experiência no curso é positiva para o conjunto dos estudantes havendo necessidade de observar com mais atenção as questões relacionadas com a avaliação. A grande maioria dos estudantes revela também satisfação com o curso que frequenta. Palavras-Chave: Experiência no Curso; Tutorias de Acompanhamento; CEQP; Ensino Superior. Abstract This study examine the experience in the course of the 1st year students who entered at the University of Évora. Studies on the perception of students on the learning environment in higher education indicate a strong relationship with the approaches to learning and have strong relevance to the understanding how students access the knowledge and the definition of high quality learning processes (Entwistle, 2009; Chaleta & Entwistle, 2011). The data were obtained by applying the CEQP (Ramsden, 2005, 2006; Chaleta et al, 2012) with 565 students from different courses and scientific areas. The results indicated that the course experience is positive for all the students but we need to look more closely at the issues related to assessment. The vast majority of students also reveals satisfaction with the course who attends Keywords: Course Experience; Mentor Monitoring; CEQP; Higher Education

Predicting quality attributes of strawberry packed under modified atmosphere throughout the cold chain

Modified Atmosphere Packaging (MAP) is used commercially to extend the shelf life of strawberries. The attainment of desired gas (O2, CO2) concentrations inside MAP relies on the product respiration and the mass transfer through packaging and will affect the quality. The objective of this work is to build a mathematical model for strawberries to assess the effect of the uncertainties on headspace gas concentration and quality: 1) cold chain related temperature and relative humidity variations and 2) variability associated to product respiration and quality based on literature. Weight loss was more influenced by the cold chain storage conditions (temperature and RH) whereas spoilage had similar influence of cold chain conditions and product parameters. Waste generated in the cold chain was estimated from industrial standard weight loss and spoilage thresholds. A sensitivity analysis of the stochastic MAP model showed the influence of input parameters on the quality pointing to interventions associated to a reduction of the respiration rate (e.g. modification of packaging) and reduction of water transfer (e.g. coating) may prove more successful than other interventions to which the waste generation of this product is not so sensitive to. As a conclusion this work presents a toolbox to interpret cold chain data: 1) develop mathematical models to predict fate of quality 2) simulate cold chain conditions allowing for uncertainty 3) estimate the waste generation kinetics based in quality criteria and thresholds 4) perform a sensitivity analysis to identify most sensitive technological parameters 5) identify interventions that will affect those technological parameters. Keywords: Mathematical modelling; Coating; Variability; Sensitivity analysis; Strawberr