Optimal approximation of fractional derivatives through discrete-time fractions using genetic algorithms

This study addresses the optimization of rational fraction approximations for the discrete-time calculation of fractional derivatives. The article starts by analyzing the standard techniques based on Taylor series and Padé expansions. In a second phase the paper re-evaluates the problem in an optimization perspective by tacking advantage of the flexibility of the genetic algorithms.

Approximating fractional derivatives through the generalized mean

This paper addresses the calculation of fractional order expressions through rational fractions. The article starts by analyzing the techniques adopted in the continuous to discrete time conversion. The problem is re-evaluated in an optimization perspective by tacking advantage of the degree of freedom provided by the generalized mean formula. The results demonstrate the superior performance of the new algorithm.

Silloitushitsauksen robotisointi

Tämän diplomityön tavoitteena oli tutkia ja selvittää kuormakoneen takarunkorakenteen silloitushitsauksen robotisointia. Työ päätettiin rajata koskemaan vain tiettyä moduulia takarungosta. Työssä kartoitettiin tarvittava laitteisto, selvitettiin runkomoduulin silloitusajat sekä arvioitiin investoinnin kannattavuutta. Silloituksen suorittavan järjestelmän vaatimuksena oli, että sen tulee asettaa osat paikoilleen hitsauskiinnittimeen ja tehdä tarvittavat silloitushitsaukset automaattisesti. Sopivaksi laitteistoksi osoittautui taloudellisuuden ja toiminnallisuuden näkökulmasta yhdestä kappaleenkäsittely- sekä hitsausrobotista muodostuva järjestelmä. Kappaleenkäsittelijän ohjauksessa käytetään konenäköä sekä osien paikannuksessa että laadunvarmistuksessa. Robotit liikkuvat yhteisellä lineaariradalla, jonka rinnalla on kappaleenkäsittelylaitteistoja hitsauskiinnittimineen. Robotisoinnin käyttöönotolla yhden takarungon moduulien kokoonpanoon ja silloitukseen käytettävä aika pienenee alle puoleen manuaaliseen työhön verrattuna. Näin saavutetaan merkittäviä kustannussäästöjä. Lisäksi hitsauskiinnittimet voivat olla verrattain yksinkertaisia manuaalityöhön verrattuna, jolloin myös säästetään työkaluinvestoinneissa. Robotisointiprojektin jatkotoimenpiteitä ovat laajamittaiset tuotantosimulaatiot layoutin, laitteiston sekä työkiertojen tarkaksi määrittämiseksi. Lisäksi itse tuotetta on muokattava paremmin robottisilloitukseen sopivaksi.

Stochastic modelling considering ionospheric scintillation effects on GNSS relative and point positioning

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação bacteriológica de águas minerais sem gás e gaseificadas artificialmente comercializadas em garrafs individuais

Pós-graduação em Alimentos e Nutrição - FCFAR

Design methodologies of microwawe integrated circuits for satellite telecommunications

The running innovation processes of the microwave transistor technologies, used in the implementation of microwave circuits, have to be supported by the study and development of proper design methodologies which, depending on the applications, will fully exploit the technology potentialities. After the choice of the technology to be used in the particular application, the circuit designer has few degrees of freedom when carrying out his design; in the most cases, due to the technological constrains, all the foundries develop and provide customized processes optimized for a specific performance such as power, low-noise, linearity, broadband etc. For these reasons circuit design is always a “compromise”, an investigation for the best solution to reach a trade off between the desired performances. This approach becomes crucial in the design of microwave systems to be used in satellite applications; the tight space constraints impose to reach the best performances under proper electrical and thermal de-rated conditions, respect to the maximum ratings provided by the used technology, in order to ensure adequate levels of reliability. In particular this work is about one of the most critical components in the front-end of a satellite antenna, the High Power Amplifier (HPA). The HPA is the main power dissipation source and so the element which mostly engrave on space, weight and cost of telecommunication apparatus; it is clear from the above reasons that design strategies addressing optimization of power density, efficiency and reliability are of major concern. Many transactions and publications demonstrate different methods for the design of power amplifiers, highlighting the availability to obtain very good levels of output power, efficiency and gain. Starting from existing knowledge, the target of the research activities summarized in this dissertation was to develop a design methodology capable optimize power amplifier performances complying all the constraints imposed by the space applications, tacking into account the thermal behaviour in the same manner of the power and the efficiency. After a reminder of the existing theories about the power amplifier design, in the first section of this work, the effectiveness of the methodology based on the accurate control of the dynamic Load Line and her shaping will be described, explaining all steps in the design of two different kinds of high power amplifiers. Considering the trade-off between the main performances and reliability issues as the target of the design activity, we will demonstrate that the expected results could be obtained working on the characteristics of the Load Line at the intrinsic terminals of the selected active device. The methodology proposed in this first part is based on the assumption that designer has the availability of an accurate electrical model of the device; the variety of publications about this argument demonstrates that it is so difficult to carry out a CAD model capable to taking into account all the non-ideal phenomena which occur when the amplifier operates at such high frequency and power levels. For that, especially for the emerging technology of Gallium Nitride (GaN), in the second section a new approach for power amplifier design will be described, basing on the experimental characterization of the intrinsic Load Line by means of a low frequency high power measurements bench. Thanks to the possibility to develop my Ph.D. in an academic spin-off, MEC – Microwave Electronics for Communications, the results of this activity has been applied to important research programs requested by space agencies, with the aim support the technological transfer from universities to industrial world and to promote a science-based entrepreneurship. For these reasons the proposed design methodology will be explained basing on many experimental results.

Temporary scaffolding of coronary arteries with bioabsorbable magnesium stents: a prospective, non-randomised multicentre trial

BACKGROUND: Coronary stents improve immediate and late results of balloon angioplasty by tacking up dissections and preventing wall recoil. These goals are achieved within weeks after angioplasty, but with current technology stents permanently remain in the artery, with many limitations including the need for long-term antiplatelet treatment to avoid thrombosis. We report a prospective multicentre clinical trial of coronary implantations of absorbable magnesium stents. METHODS: We enrolled 63 patients (44 men; mean age 61.3 [SD 9.5 years]) in eight centres with single de novo lesions in a native coronary artery in a multicentre, non-randomised prospective study. Follow-up included coronary angiography and intravascular ultrasound at 4 months and clinical assessment at 6 months and 12 months. The primary endpoint was cardiac death, non-fatal myocardial infarction, or clinically driven target lesion revascularisation at 4 months FINDINGS: 71 stents, 10-15 mm in length and 3.0-3.5 mm in diameter, were successfully implanted after pre-dilatation in 63 patients. Diameter stenosis was reduced from 61.5 (SD 13.1%) to 12.6 (5.6%) with an acute gain of 1.41 mm (0.46 mm) and in-stent late loss of 1.08 mm (0.49 mm). The ischaemia-driven target lesion revascularisation rate was 23.8% after 4 months, and the overall target lesion revascularisation rate was 45% after 1 year. No myocardial infarction, subacute or late thrombosis, or death occurred. Angiography at 4 months showed an increased diameter stenosis of 48.4 (17.0%). After serial intravascular ultrasound examinations, only small remnants of the original struts were visible, well embedded into the intima. Neointimal growth and negative remodelling were the main operating mechanisms of restenosis. INTERPRETATION: This study shows that biodegradable magnesium stents can achieve an immediate angiographic result similar to the result of other metal stents and can be safely degraded after 4 months. Modifications of stent characteristics with prolonged degradation and drug elution are currently in development.

Valutazione del rischio ecologico e sviluppo di strategie innovative per il monitoraggio della qualita’ dei corpi idrici: applicazione di un nuovo approccio integrato in un bacino pilota.

Freshwater is extremely precious; but even more precious than freshwater is clean freshwater. From the time that 2/3 of our planet is covered in water, we have contaminated our globe with chemicals that have been used by industrial activities over the last century in a unprecedented way causing harm to humans and wildlife. We have to adopt a new scientific mindset in order to face this problem so to protect this important resource. The Water Framework Directive (European Parliament and the Council, 2000) is a milestone legislative document that transformed the way that water quality monitoring is undertaken across all Member States by introducing the Ecological and Chemical Status. A “good or higher” Ecological Status is expected to be achieved for all waterbodies in Europe by 2015. Yet, most of the European waterbodies, which are determined to be at risk, or of moderate to bad quality, further information will be required so that adequate remediation strategies can be implemented. To date, water quality evaluation is based on five biological components (phytoplankton, macrophytes and benthic algae, macroinvertebrates and fishes) and various hydromorphological and physicochemical elements. The evaluation of the chemical status is principally based on 33 priority substances and on 12 xenobiotics, considered as dangerous for the environment. This approach takes into account only a part of the numerous xenobiotics that can be present in surface waters and could not evidence all the possible causes of ecotoxicological stress that can act in a water section. The mixtures of toxic chemicals may constitute an ecological risk not predictable on the basis of the single component concentration. To improve water quality, sources of contamination and causes of ecological alterations need to be identified. On the other hand, the analysis of the community structure, which is the result of multiple processes, including hydrological constrains and physico-chemical stress, give back only a “photograph” of the actual status of a site without revealing causes and sources of the perturbation. A multidisciplinary approach, able to integrate the information obtained by different methods, such as community structure analysis and eco-genotoxicological studies, could help overcome some of the difficulties in properly identifying the different causes of stress in risk assessment. In synthesis, the river ecological status is the result of a combination of multiple pressures that, for management purposes and quality improvement, have to be disentangled from each other. To reduce actual uncertainty in risk assessment, methods that establish quantitative links between levels of contamination and community alterations are needed. The analysis of macrobenthic invertebrate community structure has been widely used to identify sites subjected to perturbation. Trait-based descriptors of community structure constitute a useful method in ecological risk assessment. The diagnostic capacity of freshwater biomonitoring could be improved by chronic sublethal toxicity testing of water and sediment samples. Requiring an exposure time that covers most of the species’ life cycle, chronic toxicity tests are able to reveal negative effects on life-history traits at contaminant concentrations well below the acute toxicity level. Furthermore, the responses of high-level endpoints (growth, fecundity, mortality) can be integrated in order to evaluate the impact on population’s dynamics, a highly relevant endpoint from the ecological point of view. To gain more accurate information about potential causes and consequences of environmental contamination, the evaluation of adverse effects at physiological, biochemical and genetic level is also needed. The use of different biomarkers and toxicity tests can give information about the sub-lethal and toxic load of environmental compartments. Biomarkers give essential information about the exposure to toxicants, such as endocrine disruptor compounds and genotoxic substances whose negative effects cannot be evidenced by using only high-level toxicological endpoints. The increasing presence of genotoxic pollutants in the environment has caused concern regarding the potential harmful effects of xenobiotics on human health, and interest on the development of new and more sensitive methods for the assessment of mutagenic and cancerogenic risk. Within the WFD, biomarkers and bioassays are regarded as important tools to gain lines of evidence for cause-effect relationship in ecological quality assessment. Despite the scientific community clearly addresses the advantages and necessity of an ecotoxicological approach within the ecological quality assessment, a recent review reports that, more than one decade after the publication of the WFD, only few studies have attempted to integrate ecological water status assessment and biological methods (namely biomarkers or bioassays). None of the fifteen reviewed studies included both biomarkers and bioassays. The integrated approach developed in this PhD Thesis comprises a set of laboratory bioassays (Daphnia magna acute and chronic toxicity tests, Comet Assay and FPG-Comet) newly-developed, modified tacking a cue from standardized existing protocols or applied for freshwater quality testing (ecotoxicological, genotoxicological and toxicogenomic assays), coupled with field investigations on macrobenthic community structures (SPEAR and EBI indexes). Together with the development of new bioassays with Daphnia magna, the feasibility of eco-genotoxicological testing of freshwater and sediment quality with Heterocypris incongruens was evaluated (Comet Assay and a protocol for chronic toxicity). However, the Comet Assay, although standardized, was not applied to freshwater samples due to the lack of sensitivity of this species observed after 24h of exposure to relatively high (and not environmentally relevant) concentrations of reference genotoxicants. Furthermore, this species demonstrated to be unsuitable also for chronic toxicity testing due to the difficult evaluation of fecundity as sub-lethal endpoint of exposure and complications due to its biology and behaviour. The study was applied to a pilot hydrographic sub-Basin, by selecting section subjected to different levels of anthropogenic pressure: this allowed us to establish the reference conditions, to select the most significant endpoints and to evaluate the coherence of the responses of the different lines of evidence (alteration of community structure, eco-genotoxicological responses, alteration of gene expression profiles) and, finally, the diagnostic capacity of the monitoring strategy. Significant correlations were found between the genotoxicological parameter Tail Intensity % (TI%) and macrobenthic community descriptors SPEAR (p<0.001) and EBI (p<0.05), between the genotoxicological parameter describing DNA oxidative stress (ΔTI%) and mean levels of nitrates (p<0.01) and between reproductive impairment (Failed Development % from D. magna chronic bioassays) and TI% (p<0.001) as well as EBI (p<0.001). While correlation among parameters demonstrates a general coherence in the response to increasing impacts, the concomitant ability of each single endpoint to be responsive to specific sources of stress is at the basis of the diagnostic capacity of the integrated approach as demonstrated by stations presenting a mismatch among the different lines of evidence. The chosen set of bioassays, as well as the selected endpoints, are not providing redundant indications on the water quality status but, on the contrary, are contributing with complementary pieces of information about the several stressors that insist simultaneously on a waterbody section providing this monitoring strategy with a solid diagnostic capacity. Our approach should provide opportunities for the integration of biological effects into monitoring programmes for surface water, especially in investigative monitoring. Moreover, it should provide a more realistic assessment of impact and exposure of aquatic organisms to contaminants. Finally this approach should provide an evaluation of drivers of change in biodiversity and its causalities on ecosystem function/services provision, that is the direct and indirect contributions to human well-being.

Is question answering fit for the semantic web? A survey

With the recent rapid growth of the Semantic Web (SW), the processes of searching and querying content that is both massive in scale and heterogeneous have become increasingly challenging. User-friendly interfaces, which can support end users in querying and exploring this novel and diverse, structured information space, are needed to make the vision of the SW a reality. We present a survey on ontology-based Question Answering (QA), which has emerged in recent years to exploit the opportunities offered by structured semantic information on the Web. First, we provide a comprehensive perspective by analyzing the general background and history of the QA research field, from influential works from the artificial intelligence and database communities developed in the 70s and later decades, through open domain QA stimulated by the QA track in TREC since 1999, to the latest commercial semantic QA solutions, before tacking the current state of the art in open user-friendly interfaces for the SW. Second, we examine the potential of this technology to go beyond the current state of the art to support end-users in reusing and querying the SW content. We conclude our review with an outlook for this novel research area, focusing in particular on the R&D directions that need to be pursued to realize the goal of efficient and competent retrieval and integration of answers from large scale, heterogeneous, and continuously evolving semantic sources.

Analyse du rôle de l'IFREMER dans l'instruction du dossier Salmor

This report describes the contribution made by IFREMER in the various stages of installation of a new salmon culture in barge's tanks moored in Morlaix Bay. Tacking into account the opposition to this project, including direct criticism of the role of IFREMER, a considerable effort is made to provide detailed environmental impact data to the appropriate Government office

The difference of Being in the early modern world: a relational-material approach to life in Scotland in the period of the witch trials

This thesis investigates how ways of being in different ontologies emerge from material and embodied practice. This general concern is explored through the particular case study of Scotland in the period of the witch trials (the 16th and 17th centuries C.E.). The field of early modern Scottish witchcraft studies has been active and dynamic over the past 15 years but its prioritisation of what people said over what they did leaves a clear gap for a situated and relational approach focusing upon materiality. Such an approach requires a move away from the Cartesian dichotomies of modern ontology to recognise past beliefs as real to those who experienced them, coconstitutive of embodiment and of the material worlds people inhabited. In theory, method and practice, this demands a different way of exploring past worlds to avoid flattening strange data. To this end, the study incorporates narratives and ‘disruptions’ – unique engagements with Contemporary Art which facilitate understanding by enabling the temporary suspension of disbelief. The methodology is iterative, tacking between material and written sources in order to better understand the heterogeneous assemblages of early modern (counter-) witchcraft. Previously separate areas of discourse are (re-)constituted into alternative ontic categories of newly-parallel materials. New interpretations of things, places, bodies and personhoods emerge, raising questions about early modern experiences of the world. Three thematic chapters explore different sets of collaborative agencies as they entwine into new things, co-fabricating a very different world. Moving between witch trial accounts, healing wells, infant burial grounds, animals, discipline artefacts and charms, the boundaries of all prove highly permeable. People, cloth and place bleed into one another through contact; trees and water emerge as powerful agents of magical-place-making; and people and animals meet to become single, hybrid-persons spread over two bodies. Life and death consistently emerge as protracted processes with the capacity to overlap and occur simultaneously in problematic ways. The research presented in this thesis establishes a new way of looking at the nature of Being as experienced by early modern Scots. This provides a foundation for further studies, which can draw in other materials not explored here such as communion wares and metal charms. Comparison with other early modern Western societies may also prove fruitful. Furthermore, the methodology may be suitable for application to other interdisciplinary projects incorporating historical and material evidence.