Caracterização estrutural e paragenética do Campo Pegmatítico do Licungo (Mocuba, Moçambique): identificação de recursos base associados

Publicado em "A engenharia no combate à pobreza, pelo desenvolvimento e competitividade", ISBN 978-972-8826-19-2Geological thematic mapping in Licungo pegmatite field (Mocuba, Mozambique) has clarified the distribution of mineral resources in NYF hyperaluminous pegmatites and revealed its structural control. Two distinct spatial and deformational areas can be distinguished. In the north structural domain, large pegmatites are associated with early tangential tectonic. Besides feldspar with ceramic qualification, industrial beryl and gems are also non-systematic resources. Small pegmatite dykes predominate in the south domain and their emplacement is conditioned by later distensive phases (Dn+1 and Dn+2). Their economic interest comes from gem beryl enrichment and its crystallisation as true-blue varieties

Optimal location and setting of time modulated PRVs for water loss reduction with leakage modelling by pressure driven analysis

Water losses have economical, technical, social and environmental negative impacts and so water companies are always willing to reduce them. The IWA Water Loss Task Force identified four main control strategies to reduce real losses: 1) infrastructure management; 2) pressure management; 3) active leakage control; and 4) speed and quality of repairs. Unreported leaks and background leakage usually represent a major component of water losses and pressure management is an effective, easy, economic and quick solution to reduce it. Pressure management can be implemented by introducing Pressure Reduction Valves (PRVs): fixed-outlet; time-modulated; flow-modulated and pressure modulated. For a fixed-outlet PRV there is a single working condition (pressure downstream of the PRV is always the same). For a time-modulated PRV there can be several working conditions (for instance, a lower pressure during the night period - from 0 to 6 am, and higher one during the remainder of the day). The flow-modulated and pressure modulated PRVs are more efficient because they constantly try to adjust the working conditions to reach the minimum pressure required at the critical node. However, pressure management projects must be preceded by specialized studies (identify the optimal location and settings of the PRVs to install) and cost benefit analysis (assessment of economic viability). A previous work presented a methodology to help in those tasks, by identifying the optimal location and setting of fixed-outlet PRVs to reduce water losses in WDNs and maximize the NPV of pressure management projects. Now the methodology was extended to include also time modulated PRVs and this paper presents the results obtained for a hypothetical case study.info:eu-repo/semantics/publishedVersio

Optimal District Metered Area Design by Simulated Annealing

Water losses reduction in Water Distribution Systems (WDSs) is nowadays an issue of growing importance for water companies to ensure the economic sustainability of these public services. In this context, the implementation of District Metered Areas (DMAs) and/or pressure management are considered effective tools for leakage control, particularly in large networks and in systems with deteriorated infrastructures and with high pressure. Based in previous studies performed by the authors (Gomes et al., 2012; Gomes et al., 2015; Sousa et al., 2015), the methodology described in this paper follows the ‘water losses management international best practices’ and makes it possible to evaluate the Net Present Value (NPV) of DMAs project, as well as the benefits that can be achieved by pressure management in WDS, particularly in terms of water production reduction. Leakage assessment is performed using the analysis of the minimum night flow and the FAVAD concept, and it uses a pressure driven simulation model to predict the network hydraulic behaviour under different pressure conditions. The optimal location of DMAs entry points, pipes reinforcement/replacement and locations/settings of the Pressure Reduction Valves (PRVs) are identified by a Simulated Annealing algorithm. The potential of this methodology is illustrated through an hypothetical case study.info:eu-repo/semantics/publishedVersio

Water Distribution Network Reliability: are Surrogate Measures Reliable?

Water distribution networks (WDNs) must be reliable infrastructures since they provide an essential service to society. Reliability assessment is a complex task and involves various aspects: mechanical, hydraulic, water quality, water safety, among others. This paper focus is on the hydraulic reliability. Hydraulic reliability is computationally hard to measure directly, therefore researchers came up with surrogate measures, like the resilience index, the modified resilience index, the flow entropy or the diameter-sensitive flow entropy, that are simple and fast to compute. But, are these surrogate measures reliable to be used in the design of WDNs? This paper proposes a new reliability index based on the surplus flow available on each node to mitigate the effects of a pipe failure. To illustrate the applicability of this new index, a WDN example is optimally designed (simulated annealing algorithm embedded in WaterNetGen) in order to maximize some reliability index subject to a given budget. Results show that the solutions based on the flow entropy or the proposed index are more reliable than the others, and, also, the maximization of the other reliability indexes gives only a residual contribution to the global reliability (or even no contribution at all).info:eu-repo/semantics/publishedVersio

Use of CPAP to Reduce Arterial Stiffness in Moderate-to-Severe Obstructive Sleep Apnoea, Without Excessive Daytime Sleepiness (STIFFSLEEP): an Observational Cohort Study Protocol

INTRODUCTION: Sleepiness is a cardinal symptom in obstructive sleep apnoea (OSA) but most patients have unspecific symptoms. Arterial stiffness, evaluated by pulse wave velocity (PWV), is related to atherosclerosis and cardiovascular (CV) risk. Arterial stiffness was reported to be higher in patients with OSA, improving after treatment with continuous positive airway pressure (CPAP). This study aims to assess whether the same effect occurs in patients with OSA and without sleepiness. METHODS AND ANALYSIS: This observational study assesses the CV effect of CPAP therapy on a cohort of patients with moderate-to-severe OSA; the effect on the subcohorts of sleepy and non-sleepy patients will be compared. A systematic and consecutive sample of patients advised CPAP therapy will be recruited from a single outpatient sleep clinic (Centro Hospitalar de Lisboa Central-CHLC, Portugal). Eligible patients are male, younger than 65 years, with confirmed moderate-to-severe OSA and apnoea-hypopnea index (AHI) above 15/hour. Other sleep disorders, diabetes or any CV disease other than hypertension are exclusion criteria. Clinical evaluation at baseline includes Epworth Sleepiness Scale (ESS), and sleepiness is defined as ESS above 10. OSA will be confirmed by polygraphic study (cardiorespiratory, level 3). Participants are advised to undertake an assessment of carotid-femoral PWV (cf-PWV) and 24 hours evaluation of ambulatory blood pressure monitoring (ABPM), at baseline and after 4 months of CPAP therapy. Compliance and effectiveness of CPAP will be assessed. The main outcome is the variation of cf-PWV over time

T.08 - Engrenagens de parafuso sem-fim

Neste documento aborda-se o tema das engrenagens de parafuso sem-fim, o qual é lecionado no âmbito da unidade curricular Órgãos de Máquinas II, do curso de Mestrado Integrado em Engenharia Mecânica da Universidade do Minho. Com efeito, inicia-se este assunto com uma breve introdução, após a qual se apresenta o estudo relativo à geração do dente. Seguidamente faz-se uma breve referência aos perfis dos filetes deste tipo de engrenagens. De seguida apresenta-se a principal nomenclatura utilizada em engrenagens de parafuso sem-fim, apresentando-se o estudo da relação de transmissão. Seguidamente, estudam-se as principais relações geométricas a ter em consideração neste tipo de engrenagens. Depois dá-se particular relevo aos parâmetros de desempenho de engrenagens de parafuso sem-fim, nomeadamente a relação de condução e o rendimento. Finalmente, termina-se este documento com uma breve lista de questões de revisão de conhecimentos, assim como uma lista de referências bibliográficas

Emplacement and affiliation of Licungo pegmatites – Zambezia, Mozambique

A instalação dos conjuntos pegmatíticos no Licungo é controlada por lineamentos NNE-SSW e NNW-SSE e a dimensão e morfologia dos pegmatitos é influenciada por carreamentos que também induziram nas rochas encaixantes uma foliação subhorizontal. Os corpos maiores terão sido acolhidos por volumes transtensivos. A deformação subsequente modificou atitudes, mas as paragéneses e as estruturas são pouco variáveis ao nível do campo pegmatítico: predomina a feição NYF. Isto sugere uma afinidade genética com granitos de tipo alcalino que afloram a Este na região de Ethabo.The emplacement of Licungo pegmatites is controlled by NNE-SSW and NNW-SSE lineaments, and the dimension and morphology of single bodies are influenced by the same obduction that is responsible for the most penetrative sub-horizontal foliation at the host-rocks. Major pegmatites are located in tangential pull-a-part volumes. In most internal structures and paragenesis NYF character is dominant. This suggests a genetic affiliation to alkaline granite stocks outcropping to the east in Ethabo region

Calibration in Water Distribution Networks with Pressure-Driven Analysis

Water distribution networks (WDN) connect consumers to the water sources, and its goal is to fulfil water demand. However, it is a well-known fact that WDN have losses and an important part of them occur at pipe level. Despite all the research efforts focused on this subject, the identification of leaky pipes is still a major challenge. EPANET is frequently used to simulate WDN’ models, using a link-node formulation, similar to a graph, where the water demands are assigned to the nodes. A linearized system of equations (mass and energy conservation laws) is iteratively solved by a Newton-Raphson algorithm. The EPANET is demand-driven, since it assumes the water pressure is always enough to satisfy the demands. However, on real WDN, states of insufficient pressure also occur. Besides that, the demand-driven approach is not suitable for pipe leakage simulation, which depends on the pressure. WaterNetGen — an EPANET extension— allows both demand and pressure driven simulations, including pipes’ leakage modelling. However, the leakage parameters (bursts and background leakage coefficients and exponents) must be set manually by an expert — manual calibration — for the whole network or for each pipe. This work proposes a calibration methodology to estimate the pipe background leakage parameters. The approach is tested on a set of synthetic models, generated by WaterNetGen, and then applied to a real WDN to assess its performance on real world conditions.info:eu-repo/semantics/publishedVersio

Bronchiectasis: A retrospective study of clinical and aetiological investigation in a general respiratory department

AbstractBackgroundBronchiectasis can result from many diseases, which makes the aetiological investigation a complex process demanding special resources and experience. The aetiological diagnosis has been proven to be useful for the therapeutic approach.ObjectiveEvaluate how accurately and extensive the clinical and aetiological research was for adult bronchiectasis patients in pulmonology outpatient service which were not following a pre-existing protocol.MethodsWe retrospectively reviewed the records of 202 adult patients with bronchiectasis, including the examinations performed to explain the aetiology.ResultsThe mean age of the patients was 54±15 years, there was a predominance of female (63.9%) and non-smoker (70%) patients. Functional evaluation showed a mild airway obstruction.The sputum microbiological examination was available for 168 patients (43.1% had 3 or more sputum examinations during one year). Immunoglobulins and α1-antitrypsin were measured in around 50% of the patients. The sweat test and the CF genotyping test were performed in 18% and 17% of the patients, respectively.The most commonly identified cause was post-infectious (30.3%), mostly tuberculosis (27.2%). No definitive aetiological diagnosis was established in 57.4% of the patients. We achieved a lower aetiological diagnosis if we compare our series with studies in which a diagnostic algorithm was applied prospectively.ConclusionsThe general characteristics of our patients were similar with other series. Detailed investigation of bronchiectasis is not a standard practice in our outpatient service. These results suggest that the use of a predefined protocol, based on current guidelines, could improve the assessment of these patients and facilitate the achievement of a definitive aetiology