4,122 research outputs found
Sustainability Assessment of indicators for integrated water resources management
The scientific community strongly recommends the adoption of indicators for the evaluation and monitoring of progress towards sustainable development. Furthermore, international organizations consider that indicators are powerful decision-making tools. Nevertheless, the quality and reliability of the indicators depends on the application of adequate and appropriate criteria to assess them. The general objective of this study was to evaluate how indicators related to water use and management perform against a set of sustainability criteria. Our research identified 170 indicators related to water use and management. These indicators were assessed by an international panel of experts that evaluated whether they fulfil the four sustainability criteria: social, economic, environmental, and institutional. We employed an evaluation matrix that classified all indicators according to the DPSIR (Driving Forces, Pressures, States, Impacts and Responses) framework. A pilot study served to test and approve the research methodology before carrying out the full implementation. The findings of the study show that 24 indicators comply with the majority of the sustainability criteria; 59 indicators are bi-dimensional (meaning that they comply with two sustainability criteria); 86 are one-dimensional indicators (fulfilling just one of the four sustainability criteria) and one indicator do not fulfil any of the sustainability criteria.Postprint (author's final draft
Model transcriptional networks with continuously varying expression levels
<p>Abstract</p> <p>Background</p> <p>At a time when genomes are being sequenced by the hundreds, much attention has shifted from identifying genes and phenotypes to understanding the networks of interactions among genes. We developed a gene network developmental model expanding on previous models of transcription regulatory networks. In our model, each network is described by a matrix representing the interactions between transcription factors, and a vector of continuous values representing the transcription factor expression in an individual.</p> <p>Results</p> <p>In this work we used the gene network model to look at the impact of mating as well as insertions and deletions of genes in the evolution of complexity of these networks. We found that the natural process of diploid mating increases the likelihood of maintaining complexity, especially in higher order networks (more than 10 genes). We also show that gene insertion is a very efficient way to add more genes to a network as it provides a much higher chance of developmental stability.</p> <p>Conclusions</p> <p>The continuous model affords a more complete view of the evolution of interacting genes. The notion of a continuous output vector also incorporates the reality of gene networks and graded concentrations of gene products.</p
Evaluation of two fundamental positive-sequence detectors for highly distorted and unbalanced systems
This paper presents an evaluation of the performance of two different Positive-Sequence Detectors. This evaluation is made by comparing a PLL (Phase-Locked- Loop), combined with Lagrange Multipliers Method, with an Adaptive
Filter. Both algorithms aim to detect the positive sequence at the fundamental frequency on a given three-phase system voltages or currents. The purpose of this evaluation is to assess the better Positive-Sequence Detector for custom power devices, such as Active Power Filters. The comparative analysis was based on the evaluation of a series of steady state performance arameters
(phase and amplitude errors, THD and unbalance) and on the response time. The tests were made to study the behavior of both approaches when working with highly distorted and unbalanced
signals. This work was carried out using the computer simulation tool PSCAD/EMTDC.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EEA-EEL/104569/2008.FEDER Funds - Operational Programme for Competitiveness Factors –
COMPET
Single-phase series active conditioner for the compensation of voltage harmonics, sags, swell and flicker
Simulation and experimental results shown on this
paper describes the performance of a developed Single-Phase Series Active Conditioner that regulates the voltage being
delivered to a load. This Custom Power device is a solution for power quality issues related with voltage amplitude variations, which are responsible for innumerous flaws in industrial processes which brings with it high financial losses. The Single-Phase Series Active Conditioner is a back-to-back converter,
composed by two power converters sharing a common DC link.
One of the converters is series connected to the electrical grid,
whereas the other one is shunt connected. The first is used to
compensate load voltage, and the second to regulate the DC link
voltage. This paper shows the results obtained with the Series
Active Conditioner in Sag, Swell and Flicker events, and also
Voltage Harmonics compensation, in order to deliver to the load
a sinusoidal voltage, at nominal amplitude.Fundação para a Ciência e Tecnologia (FCT
Comparisons between synchronizing circuits to control algorithms for single-phase active converters
This paper presents a comparative analysis between synchronizing circuits applied to control algorithms for single-phase active converters. One of these synchronizing circuits corresponds to the single-phase PLL (Phase Locked Loop), implemented in α-β coordinates, whereas the other one corresponds to the E-PLL (Enhanced PLL). These synchronizing circuits are compared in several aspects as processing and settling time and memory space requirements. Moreover, the performance of a single-phase back-to-back converter is also presented, with its control algorithm based on these Synchronizing Circuits. Each one of the control algorithms were implemented in a DSP microprocessor TMS320F2812F from Texas Instruments. Simulation and experimental results, through a back-to-back converter prototype, are presented.Fundação para a Ciência e a Tecnologia (FCT
Is this blended-learning, or another thing?
Today there are many forms of online use to support training, education and information dissemination. There's been a lot of confusion about the concept of online learning and we may not be able to get a definitive definition of it but hopefully, we can clarify concepts and the objective of this presentation is to be able to have a satisfying definition to understand the way our institution uses online content for our undergraduate students.
Online learning in higher education is often pointed out as a good alternative, in the planning and organization of
teaching/learning activities. Although there is resistance to its adherence by older or traditionalist teachers, because they do not master the tools and pedagogical innovation with digital technologies and also some resistance to the format, as it seconds the role of the teacher, shifting the axis of learning towards the student.
Our University uses currently a platform for online learning, where there are small online courses that are additinally for some of the mandatory or optative curricular courses for the first year of the Undergraduate Programme.
The structure of the online courses is normally of videos in varying number, followed by quizzes to assess the knowledge retained by the viewer of the video. It requires a minimum percentage of result to proceed to the next video. This model for training and education gives both the student and the teacher the opportunity of enrichment if, on the one hand, the student creates some autonomy, on the other hand, does not lose contact with teacher presence.info:eu-repo/semantics/acceptedVersio
21st century skills and digital skills, are one and the same thing?
The preparation of students of new generations for the labour market and for new social contexts currently requires higher education (ES) to reflect and reorganize its learning and training offer. In this sense, higher education institutions (HEIs) need to pursue a set of challenges, which include identifying and understanding the characteristics and needs of new students generations. Over the last decade's reference models on transversal competences (soft skills) have been established, classifying them on several nomenclatures as instrumental, interpersonal and systemic, but not always considering the temporal, and social, economic context of these same references. With the aim of designing an adequate formative offer, we have developed a study based on the systematization of the literature on the extent of reference models, categorization and terminology of
references, regarding competences skills and aptitudes, and reflect, if in some cases, we are talking about equal, different or complementary competences, in one single one. An asymmetry still seems evident between the needs for skills of a digitalized society and the development by HEIs of an educational offer convergent with these same needs, not only at the professional level but also of behavioural, emotional, social, cultural capacities. Moreover, unlike digital skills, 21st-century skills are not necessarily underpinned by digital technologies. If two decades ago the categorization terminology was limited to instrumental, interpersonal and systemic skills, the research in this area develops more detailed frameworks that do not separate 21st-century skills from digital skills, structuring this large set into foundation or fundamental, social and emotional skills to learn, create and innovate, emancipatory and humanistic and artistic skills. In addition, the discussion focuses on the ability of students to acquire and develop these new skills in an academic and professional context, leaving aside the ability of teachers to conduct and integrate those skills in a transversal and transdisciplinary in teaching and learning approaches.info:eu-repo/semantics/acceptedVersio
Failure mechanisms and surface roughness statistics of fractured Fontainebleau sandstone
In an effort to investigate the link between failure mechanisms and the
geometry of fractures of compacted grains materials, a detailed statistical
analysis of the surfaces of fractured Fontainebleau sandstones has been
achieved. The roughness of samples of different widths W is shown to be self
affine with an exponent zeta=0.46 +- 0.05 over a range of length scales ranging
from the grain size d up to an upper cut-off length \xi = 0.15 W. This low zeta
value is in agreement with measurements on other sandstones and on sintered
materials. The probability distributions P(delta z,delta h) of the variations
of height over different distances delta z > d can be collapsed onto a single
Gaussian distribution with a suitable normalisation and do not display
multifractal features. The roughness amplitude, as characterized by the
height-height correlation over fixed distances delta z, does not depend on the
sample width, implying that no anomalous scaling of the type reported for other
materials is present. It is suggested, in agreement with recent theoretical
work, to explain these results by the occurence of brittle fracture (instead of
damage failure in materials displaying a higher value of zeta = 0.8).Comment: 7 page
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