Potential and analysis of an osmotic power plant in the Magdalena River using experimental field-data

Producción CientíficaThe Magdalena River mouth in Colombia is studied as a candidate site for a renewable power plant via osmotic energy technology, using pressure retarded osmosis. This power generation plant would operate through the controlled mix of two flows with different salinities (river water and seawater in this case study). A preliminary design of a pressure retarded osmosis power plant is proposed here by means of experimental data acquisition on-site at the river mouth. The obtained net power production is shown to reach 6 MW, with adequate membrane power densities above 5 W/m2. These promising results consider energetic losses involved in the process, which have been further analysed to propose improvement targets in pretreatment processes and membrane permeability.Spanish Ministry of Economy through the project DPI2014-54530-R and the predoctoral grant BES-2015-073871, by the Junta de Castilla y León and European Regional Development Fund, UIC 233, and by the Banco Santander Iberoamérica Research Grants program. Field data acquisition was funded by COLCIENCIAS -Department of Science, Technology and Innovation of Colombia- by the project: 121571451074, resolution 881 – 2015

Modelos Preditivos para Ventilação Natural

A noção de desenvolvimento implica necessariamente a melhoria das condições de vida das populações, ou seja, conforto entendido em sentido lato incluindo, por exemplo, a Qualidade do Ar Interior. O recurso a sistemas AVAC para garantir as condições de conforto tem algumas desvantagens, nomeadamente o recurso a energias primárias finitas. Está hoje generalizada a ideia de que a Energia e o Ambiente são bens que têm de ser geridos e utilizados com os cuidados devidos ao que é finito. No sentido de incrementar o recurso a energias renováveis, infinitas por definição e não poluentes, apresentam-se no presente artigo modelos preditivos para ventilação natural que recorrem a duas fontes: as diferenças de temperatura exterior-interior e o vento. Estes modelos podem ser usados na fase de concepção arquitectónica para prever as renovações horárias devido à existência de aberturas na envolvente de edifícios, por exemplo em edifícios de serviços ou comerciais

Aerodynamic control of the mixing of confined, plane and co-axial jets

Turbulent mixing of confined coaxial jets is a complex dynamic process with many practical applications such as ejectors, jet pumps, industrial burners, jet engine combustion chambers, gaseous nuclear rockets, mixing chambers, afterburners, and turbofan engine mixing chambers. In this latter applications the confinement is also of basic interest because it involves a certain interacting turbulent flow phenomena, the details of which are not yet fully understood quantitatively (Ahmed and Sharma, 2000). There have been studies of different geometric and operating parameters on the turbulent mixing process of confined coaxial jets with different motivations. While a wide range of diameter ratios has been investigated in the past, no work was reported on diameter ratios below 2, which is the case with many low bypass turbofan engines with bypass ratios of 0.3 and less. Only Ahmed and Sharma (2000) reported recently detailed LDV measurements of mean and turbulence components of velocity as well as the total and static pressures over a range of velocity ratios with relevance in the present context. In their work they analyse the influence of velocity ratio on the turbulent mixing process, but there are many other parameters which influence the turbulent mixing process. This research is dedicated to the study of the turbulent mixing of parietal jets without any generated effect of swirl and without the presence of bluff bodies. The major objective was to design mixing control strategies using purely aerodynamic tools. Following a work on axisymmetric geometries, a two-dimensional geometry was adopted to study the influence of geometric and initial parameters to control the flow: confinement, inclination angle and turbulence intensity of the outer flow.Fundação para a Ciência e Tecnologia (FCT)Aeronautics and Astronautics Research Center (AeroG)Associated Laboratory in Energy, Transports and Aeronautics (LAETA

O conflito em contexto escolar: transformar barreiras em oportunidade

Nas relações que as pessoas estabelecem entre si ocorrem situações de conflito. A escola constitui um interface social propício a uma envolvência onde os conflitos proliferam face à complexidade do processo educacional. Transformar uma barreira em oportunidade é uma arte em que a formação do professor tem uma influência significativa nas decisões. Este artigo apresenta os resultados da análise de opiniões de futuros professores, relativas à gestão de conflitos, e dissemina boas práticas em contexto escolar. Deste modo, esperámos contribuir para um debate crítico-reflexivo sobre esta temática na formação inicial e para a resolução de problemas no âmbito da gestão de conflitos na comunidade escolar

A survey on the semi supervised learning paradigm in the context of speech emotion recognition

The area of Automatic Speech Emotion Recognition has been a hot topic for researchers for quite some time now. The recent breakthroughs on technology in the field of Machine Learning open up doors for multiple approaches of many kinds. However, some concerns have been persistent throughout the years where we highlight the design and collection of data. Proper annotation of data can be quite expensive and sometimes not even viable, as specialists are often needed for such a complex task as emotion recognition. The evolution of the semi supervised learning paradigm tries to drag down the high dependency on labelled data, potentially facilitating the design of a proper pipeline of tasks, single or multi modal, towards the final objective of the recognition of the human emotional mental state. In this paper, a review of the current single modal (audio) Semi Supervised Learning state of art is explored as a possible solution to the bottlenecking issues mentioned, as a way of helping and guiding future researchers when getting to the planning phase of such task, where many positive aspects from each piece of work can be drawn and combined.This work has been supported by FCT - Fundação para a Ciencia e Tecnologia within the R&D Units Project Scope: UIDB/00319/202

Improving quality of medical service with mobile health software

An increasing number of m-Health applications are being developed benefiting health service delivery. In this paper, a new methodology based on the principle of calm computing applied to diagnostic and therapeutic procedure reporting is proposed. A mobile application was designed for the physicians of one of the Portuguese major hospitals, which takes advantage of a multi-agent interoperability platform, the Agency for the Integration, Diffusion and Archive (AIDA). This application allows the visualization of inpatients and outpatients medical reports in a quicker and safer manner, in addition to offer a remote access to information. This project shows the advantages in the use of mobile software in a medical environment but the first step is always to build or use an interoperability platform, flexible, adaptable and pervasive. The platform offers a comprehensive set of services that restricts the development of mobile software almost exclusively to the mobile user interface design. The technology was tested and assessed in a real context by intensivists

Transactions Cost Theory influence in strategy research: A review through a bibliometric study in leading journals

Transaction cost theory (TCT) is widely used in several management disciplines. Its value for explaining organizational phenomena and managers? decisions is well accepted and has been recognized with two Nobel laureates (Ronald Coase and Oliver Williamson). In this paper we examine the impact of the TCT on extant research in top tier management journals. We conduct a bibliometric study supported in the analysis of citations and co-citations to uncover the connections between authors and presumably theories. We conclude that the TCT, albeit its specific focus on the transactions as the unit of analysis, is present in a majority of management- and business-related research.transaction costs theory, bibliometric study, strategy research, review

Evaluation of functionally graded ceramic crucible for induction melting of TiAl based alloys

During the last years a very significant effort to develop a melting crucible for induction melting of Ti based alloys at competitive cost has been carried out by many researchers, where the authors are included. Results obtained so far have shown that no material accomplishes the melting crucibles two main demands: inertness facing titanium alloys and suitable/enough thermal-shock resistance. Until now, yttrium and calcium oxides were those materials that performed best on what concerns to thermodynamic stability. However, in both cases, crucibles thermal-shock resistance was very poor, and there are references to crucibles that cracked during melting. Besides, calcium oxide reveals manipulation problems, due to its high higroscopicity. This paper concerns to the evaluation of zircon based crucibles with Y2O3 inner layer for induction melting of TiAl based alloys. A novel multi layered crucible production technique based in a centrifugally assisted slip casting process followed by a sintering operation is described, and results concerning to crucibles porosity and wall composition and morphology are presented. Crucibles obtained in different processing conditions were used to melt a Ti48Al alloy which was poured in graphite moulds. Experimental results include alloy chemical contamination with residual elements, mainly yttrium and oxygen, microhardness measurement and the presence of yttrium oxide and zircon inclusions in the cast samples. Results concerning to the crucibles behaviour are also presented with particular attention to cracks development. The Y2O3 crucible layer was found to suffer some erosion and be slightly dissolved by the molten alloy and the extent of those phenomena depends on the porosity of the layer surface, for fixed experimental melting conditionsFCT - Fundação para a Ciência e Tecnologi

Aluminium evaporation during ceramic crucible induction melting of titanium aluminides

Melting TiAl based alloys in ceramic crucibles often leads to chemical contamination, alloy heterogeneity and non-metallic inclusions. The severity of such phenomena usually depends on the nature of crucible materials, the melting stock composition and the melting parameters, namely superheating time and temperature and melting pressure. Among the referred drawbacks, Al loss during melting is a critical aspect, as its concentration in TiAl based alloys has a very strong effect in their mechanical properties. Although a few studies of critical factors affecting the evaporation behaviour of Al during electron beam and induction skull melting of Ti-Al alloys had been carried out, until now no information was released on this subject for the ceramic crucible induction melting process. In this work a Ti-48Al alloy was induction melted in a zircon crucible with Y2O3 inner layer, using 50 and 100 ºC superheating temperatures and 0, 60 and 90 second holding times, and poured into a graphite mould. The effect of different temperature/time combinations in the alloy composition, Al loss by evaporation and extent of the metal/crucible interaction was studied for different melting pressures. Al loss was found to increase significantly for melting pressures below around 10-1 mbar, at a rate that increases as melting pressure decreases, until a maximum rate is reached, remaining constant for lower pressure levels. Metal/crucible interaction increased directly with the melting pressure and superheating time, leading to alloy contamination with yttrium and oxygen. For the experimental set-up and conditions used on this work, optimal superheating time/pressure combinations that lead to acceptable alloy composition and sanity have been identified.FCT - Fundação para a Ciência e Tecnologi

Critical events in mechanically ventilated patients

Mechanical Ventilation is an artificial way to help a Patient to breathe. This procedure is used to support patients with respiratory diseases however in many cases it can provoke lung damages, Acute Respiratory Diseases or organ failure. With the goal to early detect possible patient breath problems a set of limit values was defined to some variables monitored by the ventilator (Average Ventilation Pressure, Compliance Dynamic, Flow, Peak, Plateau and Support Pressure, Positive end-expiratory pressure, Respiratory Rate) in order to create critical events. A critical event is verified when a patient has a value higher or lower than the normal range defined for a certain period of time. The values were defined after elaborate a literature review and meeting with physicians specialized in the area. This work uses data streaming and intelligent agents to process the values collected in real-time and classify them as critical or not. Real data provided by an Intensive Care Unit were used to design and test the solution. In this study it was possible to understand the importance of introduce critical events for Mechanically Ventilated Patients. In some cases a value is considered critical (can trigger an alarm) however it is a single event (instantaneous) and it has not a clinical significance for the patient. The introduction of critical events which crosses a range of values and a pre-defined duration contributes to improve the decision-making process by decreasing the number of false positives and having a better comprehension of the patient condition.- Fundação para a Ciência e Tecnologia within the Project Scope UID/CEC/00319/2013 . The authors would like to thank FCT (Foundation of Science and Technology, Portugal) for the financial support through the contract PTDC/EEI-SII/1302/2012 (INTCare II